diff --git a/.gitignore b/.gitignore
index 55d325aeef..905be98730 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,9 +1,9 @@
 bench_inv
 bench_ecdh
 bench_ecmult
+bench_schnorrsig
 bench_sign
 bench_verify
-bench_schnorr_verify
 bench_recover
 bench_internal
 tests
diff --git a/.travis.yml b/.travis.yml
index e11c5ced23..e785d614b1 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -11,20 +11,20 @@ cache:
   - src/java/guava/
 env:
   global:
-    - FIELD=auto  BIGNUM=auto  SCALAR=auto  ENDOMORPHISM=no  STATICPRECOMPUTATION=yes  ECMULTGENPRECISION=auto  ASM=no  BUILD=check  EXTRAFLAGS=  HOST=  ECDH=no  RECOVERY=no  EXPERIMENTAL=no  JNI=no
+    - FIELD=auto  BIGNUM=auto  SCALAR=auto  ENDOMORPHISM=no  STATICPRECOMPUTATION=yes  ECMULTGENPRECISION=auto  ASM=no  BUILD=check  EXTRAFLAGS=  HOST=  ECDH=no  RECOVERY=no  EXPERIMENTAL=no  JNI=no JNI=no SCHNORRSIG=no
     - GUAVA_URL=https://search.maven.org/remotecontent?filepath=com/google/guava/guava/18.0/guava-18.0.jar GUAVA_JAR=src/java/guava/guava-18.0.jar
   matrix:
     - SCALAR=32bit    RECOVERY=yes
-    - SCALAR=32bit    FIELD=32bit       ECDH=yes  EXPERIMENTAL=yes
+    - SCALAR=32bit    FIELD=32bit       ECDH=yes  EXPERIMENTAL=yes   SCHNORRSIG=yes
     - SCALAR=64bit
-    - FIELD=64bit     RECOVERY=yes
+    - FIELD=64bit     RECOVERY=yes      EXPERIMENTAL=yes             SCHNORRSIG=yes
     - FIELD=64bit     ENDOMORPHISM=yes
-    - FIELD=64bit     ENDOMORPHISM=yes  ECDH=yes EXPERIMENTAL=yes
+    - FIELD=64bit     ENDOMORPHISM=yes  ECDH=yes EXPERIMENTAL=yes    SCHNORRSIG=yes
     - FIELD=64bit                       ASM=x86_64
     - FIELD=64bit     ENDOMORPHISM=yes  ASM=x86_64
     - FIELD=32bit     ENDOMORPHISM=yes
     - BIGNUM=no
-    - BIGNUM=no       ENDOMORPHISM=yes RECOVERY=yes EXPERIMENTAL=yes
+    - BIGNUM=no       ENDOMORPHISM=yes RECOVERY=yes EXPERIMENTAL=yes SCHNORRSIG=yes
     - BIGNUM=no       STATICPRECOMPUTATION=no
     - BUILD=distcheck
     - EXTRAFLAGS=CPPFLAGS=-DDETERMINISTIC
@@ -67,4 +67,7 @@ before_script: ./autogen.sh
 script:
  - if [ -n "$HOST" ]; then export USE_HOST="--host=$HOST"; fi
  - if [ "x$HOST" = "xi686-linux-gnu" ]; then export CC="$CC -m32"; fi
- - ./configure --enable-experimental=$EXPERIMENTAL --enable-endomorphism=$ENDOMORPHISM --with-field=$FIELD --with-bignum=$BIGNUM --with-scalar=$SCALAR --enable-ecmult-static-precomputation=$STATICPRECOMPUTATION --with-ecmult-gen-precision=$ECMULTGENPRECISION --enable-module-ecdh=$ECDH --enable-module-recovery=$RECOVERY --enable-jni=$JNI $EXTRAFLAGS $USE_HOST && make -j2 $BUILD
+ - ./configure --enable-experimental=$EXPERIMENTAL --enable-endomorphism=$ENDOMORPHISM --with-field=$FIELD --with-bignum=$BIGNUM --with-scalar=$SCALAR --enable-ecmult-static-precomputation=$STATICPRECOMPUTATION --with-ecmult-gen-precision=$ECMULTGENPRECISION --enable-module-ecdh=$ECDH --enable-module-recovery=$RECOVERY --enable-module-schnorrsig=$SCHNORRSIG --enable-jni=$JNI $EXTRAFLAGS $USE_HOST && make -j2 $BUILD
+after_script:
+    - cat ./tests.log
+    - cat ./exhaustive_tests.log
diff --git a/Makefile.am b/Makefile.am
index f420944e8f..87076d1345 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -178,6 +178,10 @@ if ENABLE_MODULE_ECDH
 include src/modules/ecdh/Makefile.am.include
 endif
 
+if ENABLE_MODULE_SCHNORRSIG
+include src/modules/schnorrsig/Makefile.am.include
+endif
+
 if ENABLE_MODULE_RECOVERY
 include src/modules/recovery/Makefile.am.include
 endif
diff --git a/configure.ac b/configure.ac
index 2a8db0a51c..1048a83852 100644
--- a/configure.ac
+++ b/configure.ac
@@ -129,6 +129,11 @@ AC_ARG_ENABLE(module_ecdh,
     [enable_module_ecdh=$enableval],
     [enable_module_ecdh=no])
 
+AC_ARG_ENABLE(module_schnorrsig,
+    AS_HELP_STRING([--enable-module-schnorrsig],[enable schnorrsig module (experimental)]),
+    [enable_module_schnorrsig=$enableval],
+    [enable_module_schnorrsig=no])
+
 AC_ARG_ENABLE(module_recovery,
     AS_HELP_STRING([--enable-module-recovery],[enable ECDSA pubkey recovery module [default=no]]),
     [enable_module_recovery=$enableval],
@@ -512,6 +517,10 @@ if test x"$enable_module_ecdh" = x"yes"; then
   AC_DEFINE(ENABLE_MODULE_ECDH, 1, [Define this symbol to enable the ECDH module])
 fi
 
+if test x"$enable_module_schnorrsig" = x"yes"; then
+  AC_DEFINE(ENABLE_MODULE_SCHNORRSIG, 1, [Define this symbol to enable the schnorrsig module])
+fi
+
 if test x"$enable_module_recovery" = x"yes"; then
   AC_DEFINE(ENABLE_MODULE_RECOVERY, 1, [Define this symbol to enable the ECDSA pubkey recovery module])
 fi
@@ -531,11 +540,15 @@ if test x"$enable_experimental" = x"yes"; then
   AC_MSG_NOTICE([WARNING: experimental build])
   AC_MSG_NOTICE([Experimental features do not have stable APIs or properties, and may not be safe for production use.])
   AC_MSG_NOTICE([Building ECDH module: $enable_module_ecdh])
+  AC_MSG_NOTICE([Building schnorrsig module: $enable_module_schnorrsig])
   AC_MSG_NOTICE([******])
 else
   if test x"$enable_module_ecdh" = x"yes"; then
     AC_MSG_ERROR([ECDH module is experimental. Use --enable-experimental to allow.])
   fi
+  if test x"$enable_module_schnorrsig" = x"yes"; then
+    AC_MSG_ERROR([schnorrsig module is experimental. Use --enable-experimental to allow.])
+  fi
   if test x"$set_asm" = x"arm"; then
     AC_MSG_ERROR([ARM assembly optimization is experimental. Use --enable-experimental to allow.])
   fi
@@ -554,6 +567,7 @@ AM_CONDITIONAL([USE_EXHAUSTIVE_TESTS], [test x"$use_exhaustive_tests" != x"no"])
 AM_CONDITIONAL([USE_BENCHMARK], [test x"$use_benchmark" = x"yes"])
 AM_CONDITIONAL([USE_ECMULT_STATIC_PRECOMPUTATION], [test x"$set_precomp" = x"yes"])
 AM_CONDITIONAL([ENABLE_MODULE_ECDH], [test x"$enable_module_ecdh" = x"yes"])
+AM_CONDITIONAL([ENABLE_MODULE_SCHNORRSIG], [test x"$enable_module_schnorrsig" = x"yes"])
 AM_CONDITIONAL([ENABLE_MODULE_RECOVERY], [test x"$enable_module_recovery" = x"yes"])
 AM_CONDITIONAL([USE_JNI], [test x"$use_jni" = x"yes"])
 AM_CONDITIONAL([USE_EXTERNAL_ASM], [test x"$use_external_asm" = x"yes"])
@@ -576,6 +590,7 @@ echo "  with benchmarks         = $use_benchmark"
 echo "  with coverage           = $enable_coverage"
 echo "  module ecdh             = $enable_module_ecdh"
 echo "  module recovery         = $enable_module_recovery"
+echo "  module schnorrsig       = $enable_module_schnorrsig"
 echo
 echo "  asm                     = $set_asm"
 echo "  bignum                  = $set_bignum"
diff --git a/include/secp256k1.h b/include/secp256k1.h
index fc27626dd8..bbd38eba6d 100644
--- a/include/secp256k1.h
+++ b/include/secp256k1.h
@@ -447,7 +447,7 @@ SECP256K1_API int secp256k1_ecdsa_signature_serialize_compact(
 /** Verify an ECDSA signature.
  *
  *  Returns: 1: correct signature
- *           0: incorrect or unparseable signature
+ *           0: incorrect signature
  *  Args:    ctx:       a secp256k1 context object, initialized for verification.
  *  In:      sig:       the signature being verified (cannot be NULL)
  *           msg32:     the 32-byte message hash being verified (cannot be NULL)
@@ -523,6 +523,18 @@ SECP256K1_API int secp256k1_ecdsa_signature_normalize(
  */
 SECP256K1_API extern const secp256k1_nonce_function secp256k1_nonce_function_rfc6979;
 
+/** An implementation of the nonce generation function as defined in BIP-schnorr.
+ *
+ * If a data pointer is passed, it is assumed to be a pointer to 32 bytes of
+ * extra entropy. If the data pointer is NULL and this function is used in
+ * schnorrsig_sign, it produces BIP-schnorr compliant signatures.
+ * When this function is used in ecdsa_sign, it generates a nonce using an
+ * analogue of the bip-schnorr nonce generation algorithm, but with tag
+ * "BIPSchnorrNULL" instead of "BIPSchnorrDerive".
+ * The attempt argument must be 0 or the function will fail and return 0.
+ */
+SECP256K1_API extern const secp256k1_nonce_function secp256k1_nonce_function_bipschnorr;
+
 /** A default safe nonce generation function (currently equal to secp256k1_nonce_function_rfc6979). */
 SECP256K1_API extern const secp256k1_nonce_function secp256k1_nonce_function_default;
 
@@ -701,6 +713,166 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_combine(
     size_t n
 ) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
 
+/** Opaque data structure that holds a parsed and valid "x-only" public key.
+ *  An x-only pubkey encodes a positive point. That is a point whose Y
+ *  coordinate is square. It is serialized using only its X coordinate (32
+ *  bytes).
+ *
+ *  The exact representation of data inside is implementation defined and not
+ *  guaranteed to be portable between different platforms or versions. It is
+ *  however guaranteed to be 64 bytes in size, and can be safely copied/moved.
+ *  If you need to convert to a format suitable for storage, transmission, or
+ *  comparison, use secp256k1_xonly_pubkey_serialize and
+ *  secp256k1_xonly_pubkey_parse.
+ */
+typedef struct {
+    unsigned char data[64];
+} secp256k1_xonly_pubkey;
+
+/** Parse a 32-byte public key into a xonly_pubkey object.
+ *
+ *  Returns: 1 if the public key was fully valid.
+ *           0 if the public key could not be parsed or is invalid.
+ *
+ *  Args:   ctx: a secp256k1 context object.
+ *  Out: pubkey: pointer to a pubkey object. If 1 is returned, it is set to a
+ *               parsed version of input. If not, its value is undefined.
+ *  In: input32: pointer to a serialized xonly public key
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_parse(
+    const secp256k1_context* ctx,
+    secp256k1_xonly_pubkey* pubkey,
+    const unsigned char *input32
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Serialize a xonly pubkey object into a byte sequence.
+ *
+ *  Returns: 1 always.
+ *
+ *  Args:     ctx: a secp256k1 context object.
+ *  Out: output32: a pointer to a 32-byte byte array to place the
+ *                 serialized key in.
+ *  In:    pubkey: a pointer to a secp256k1_xonly_pubkey containing an
+ *                 initialized public key.
+ */
+SECP256K1_API int secp256k1_xonly_pubkey_serialize(
+    const secp256k1_context* ctx,
+    unsigned char *output32,
+    const secp256k1_xonly_pubkey* pubkey
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Compute the xonly public key for a secret key. Same as ec_pubkey_create, but
+ *  for xonly public keys.
+ *
+ *  Returns: 1 if secret was valid, public key stores
+ *           0 if secret was invalid, try again
+ *
+ *  Args:   ctx: pointer to a context object, initialized for signing (cannot be NULL)
+ *  Out: pubkey: pointer to the created xonly public key (cannot be NULL)
+ *  In:  seckey: pointer to a 32-byte private key (cannot be NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_create(
+    const secp256k1_context* ctx,
+    secp256k1_xonly_pubkey *pubkey,
+    const unsigned char *seckey
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Converts a secp256k1_pubkey into a secp256k1_xonly_pubkey. This
+ *  function optionally outputs a sign bit that can be used to convert
+ *  the secp256k1_xonly_pubkey back into the same secp256k1_pubkey.
+ *  The sign bit is 0 if the input pubkey encodes a positive point (has a Y
+ *  coordinate that is square), otherwise it is 1.
+ *
+ *  Returns: 1 if the public key was successfully converted
+ *           0 otherwise
+ *
+ *  Args:         ctx: pointer to a context object
+ *  Out: xonly_pubkey: pointer to an x-only public key object for placing the
+ *                     converted public key (cannot be NULL)
+ *              sign: sign bit of the pubkey. Can be used to reconstruct a
+ *                    public key from x-only public key (can be NULL)
+ *  In:       pubkey: pointer to a public key that is converted (cannot be
+ *                    NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_from_pubkey(
+    const secp256k1_context* ctx,
+    secp256k1_xonly_pubkey *xonly_pubkey,
+    int *is_positive,
+    const secp256k1_pubkey *pubkey
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4);
+
+/** Tweak the private key of an x-only pubkey by adding a tweak to it. The public
+ *  key of the resulting private key will be the same as the output of
+ *  secp256k1_xonly_pubkey_tweak_add called with the same tweak and corresponding
+ *  input public key.
+ *
+ *  If the public key corresponds to a positive point, tweak32 is added to the
+ *  seckey (modulo the group order). If the public key corresponds to a
+ *  negative point, tweak32 is added to the negation of the seckey (modulo the
+ *  group order).
+ *
+ *  Returns: 1 if the tweak was successfully added to seckey
+ *           0 if the tweak was out of range or the resulting private key would be
+ *             invalid (only when the tweak is the complement of the private key) or
+ *             seckey is 0.
+ *
+ *  Args:      ctx: pointer to a context object, initialized for signing (cannot be NULL)
+ *  In/Out: seckey: pointer to a 32-byte private key
+ *  In:    tweak32: pointer to a 32-byte tweak
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_privkey_tweak_add(
+    const secp256k1_context* ctx,
+    unsigned char *seckey,
+    const unsigned char *tweak32
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Tweak an x-only public key by adding tweak times the generator to it.
+ *
+ *  Returns: 1 if tweak times the generator was successfully added to pubkey
+ *           0 if the tweak was out of range or the resulting public key would be
+ *             invalid (only when the tweak is the complement of the corresponding
+ *             private key).
+ *
+ *  Args:           ctx: pointer to a context object initialized for validation
+ *                       (cannot be NULL)
+ *  Out:  output_pubkey: pointer to a public key object (cannot be NULL)
+ *          is_positive: pointer to an integer that will be set to 1 if the
+ *                       output_pubkey is positive, and 0 otherwise (cannot be NULL)
+ *  In: internal_pubkey: pointer to an x-only public key object to apply the
+ *                       tweak to (cannot be NULL)
+ *              tweak32: pointer to a 32-byte tweak (cannot be NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_tweak_add(
+    const secp256k1_context* ctx,
+    secp256k1_xonly_pubkey *output_pubkey,
+    int *is_positive,
+    const secp256k1_xonly_pubkey *internal_pubkey,
+    const unsigned char *tweak32
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5);
+
+/** Verifies that output_pubkey and is_positive is the result of calling
+ *  secp256k1_xonly_pubkey_tweak_add with internal_pubkey and tweak32.
+ *
+ *  Returns: 1 if output_pubkey is the result of tweaking the internal_pubkey with
+ *             tweak32
+ *           0 otherwise
+ *
+ *  Args:           ctx: pointer to a context object initialized for validation
+ *                       (cannot be NULL)
+ *  In:   output_pubkey: pointer to a public key object (cannot be NULL)
+ *          is_positive: 1 if output_pubkey is positive and 0 otherwise
+ *      internal_pubkey: pointer to an x-only public key object to apply the
+ *                       tweak to (cannot be NULL)
+ *              tweak32: pointer to a 32-byte tweak (cannot be NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_tweak_verify(
+    const secp256k1_context* ctx,
+    const secp256k1_xonly_pubkey *output_pubkey,
+    int is_positive,
+    const secp256k1_xonly_pubkey *internal_pubkey,
+    const unsigned char *tweak32
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/include/secp256k1_schnorrsig.h b/include/secp256k1_schnorrsig.h
new file mode 100644
index 0000000000..32a8e3481f
--- /dev/null
+++ b/include/secp256k1_schnorrsig.h
@@ -0,0 +1,125 @@
+#ifndef SECP256K1_SCHNORRSIG_H
+#define SECP256K1_SCHNORRSIG_H
+
+#include "secp256k1.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** This module implements a variant of Schnorr signatures compliant with
+ * BIP-schnorr
+ * (https://github.com/sipa/bips/blob/bip-schnorr/bip-schnorr.mediawiki).
+ */
+
+/** Opaque data structure that holds a parsed Schnorr signature.
+ *
+ *  The exact representation of data inside is implementation defined and not
+ *  guaranteed to be portable between different platforms or versions. It is
+ *  however guaranteed to be 64 bytes in size, and can be safely copied/moved.
+ *  If you need to convert to a format suitable for storage, transmission, or
+ *  comparison, use the `secp256k1_schnorrsig_serialize` and
+ *  `secp256k1_schnorrsig_parse` functions.
+ */
+typedef struct {
+    unsigned char data[64];
+} secp256k1_schnorrsig;
+
+/** Serialize a Schnorr signature.
+ *
+ *  Returns: 1
+ *  Args:    ctx: a secp256k1 context object
+ *  Out:   out64: pointer to a 64-byte array to store the serialized signature
+ *  In:      sig: pointer to the signature
+ *
+ *  See secp256k1_schnorrsig_parse for details about the encoding.
+ */
+SECP256K1_API int secp256k1_schnorrsig_serialize(
+    const secp256k1_context* ctx,
+    unsigned char *out64,
+    const secp256k1_schnorrsig* sig
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Parse a Schnorr signature.
+ *
+ *  Returns: 1 when the signature could be parsed, 0 otherwise.
+ *  Args:    ctx: a secp256k1 context object
+ *  Out:     sig: pointer to a signature object
+ *  In:     in64: pointer to the 64-byte signature to be parsed
+ *
+ * The signature is serialized in the form R||s, where R is a 32-byte public
+ * key (X coordinate only; the Y coordinate is considered to be the unique
+ * Y coordinate satisfying the curve equation that is square)
+ * and s is a 32-byte big-endian scalar.
+ *
+ * After the call, sig will always be initialized. If parsing failed or the
+ * encoded numbers are out of range, signature validation with it is
+ * guaranteed to fail for every message and public key.
+ */
+SECP256K1_API int secp256k1_schnorrsig_parse(
+    const secp256k1_context* ctx,
+    secp256k1_schnorrsig* sig,
+    const unsigned char *in64
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Create a Schnorr signature.
+ *
+ * Returns 1 on success, 0 on failure.
+ *  Args:    ctx: pointer to a context object, initialized for signing (cannot be NULL)
+ *  Out:     sig: pointer to the returned signature (cannot be NULL)
+ *  In:    msg32: the 32-byte message being signed (cannot be NULL)
+ *        seckey: pointer to a 32-byte secret key (cannot be NULL)
+ *       noncefp: pointer to a nonce generation function. If NULL, secp256k1_nonce_function_bipschnorr is used
+ *         ndata: pointer to arbitrary data used by the nonce generation function (can be NULL)
+ */
+SECP256K1_API int secp256k1_schnorrsig_sign(
+    const secp256k1_context* ctx,
+    secp256k1_schnorrsig *sig,
+    const unsigned char *msg32,
+    const unsigned char *seckey,
+    secp256k1_nonce_function noncefp,
+    void *ndata
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
+
+/** Verify a Schnorr signature.
+ *
+ *  Returns: 1: correct signature
+ *           0: incorrect or unparseable signature
+ *  Args:    ctx: a secp256k1 context object, initialized for verification.
+ *  In:      sig: the signature being verified (cannot be NULL)
+ *         msg32: the 32-byte message being verified (cannot be NULL)
+ *        pubkey: pointer to an x-only public key to verify with (cannot be NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_schnorrsig_verify(
+    const secp256k1_context* ctx,
+    const secp256k1_schnorrsig *sig,
+    const unsigned char *msg32,
+    const secp256k1_xonly_pubkey *pubkey
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
+
+/** Verifies a set of Schnorr signatures.
+ *
+ * Returns 1 if all succeeded, 0 otherwise. In particular, returns 1 if n_sigs is 0.
+ *
+ *  Args:    ctx: a secp256k1 context object, initialized for verification.
+ *       scratch: scratch space used for the multiexponentiation
+ *  In:      sig: array of pointers to signatures, or NULL if there are no signatures
+ *         msg32: array of pointers to messages, or NULL if there are no signatures
+ *            pk: array of pointers to x-only public keys, or NULL if there are no signatures
+ *        n_sigs: number of signatures in above arrays. Must be below the
+ *                minimum of 2^31 and SIZE_MAX/2. Must be 0 if above arrays are NULL.
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_schnorrsig_verify_batch(
+    const secp256k1_context* ctx,
+    secp256k1_scratch_space *scratch,
+    const secp256k1_schnorrsig *const *sig,
+    const unsigned char *const *msg32,
+    const secp256k1_xonly_pubkey *const *pk,
+    size_t n_sigs
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* SECP256K1_SCHNORRSIG_H */
diff --git a/src/bench_schnorrsig.c b/src/bench_schnorrsig.c
new file mode 100644
index 0000000000..b36499f851
--- /dev/null
+++ b/src/bench_schnorrsig.c
@@ -0,0 +1,127 @@
+/**********************************************************************
+ * Copyright (c) 2018 Andrew Poelstra                                 *
+ * Distributed under the MIT software license, see the accompanying   *
+ * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
+ **********************************************************************/
+
+#include <string.h>
+#include <stdlib.h>
+
+#include "include/secp256k1.h"
+#include "include/secp256k1_schnorrsig.h"
+#include "util.h"
+#include "bench.h"
+
+#define MAX_SIGS	(32768)
+
+typedef struct {
+    secp256k1_context *ctx;
+    secp256k1_scratch_space *scratch;
+    size_t n;
+    const unsigned char **pk;
+    const secp256k1_schnorrsig **sigs;
+    const unsigned char **msgs;
+} bench_schnorrsig_data;
+
+void bench_schnorrsig_sign(void* arg) {
+    bench_schnorrsig_data *data = (bench_schnorrsig_data *)arg;
+    size_t i;
+    unsigned char sk[32] = "benchmarkexample secrettemplate";
+    unsigned char msg[32] = "benchmarkexamplemessagetemplate";
+    secp256k1_schnorrsig sig;
+
+    for (i = 0; i < 1000; i++) {
+        msg[0] = i;
+        msg[1] = i >> 8;
+        sk[0] = i;
+        sk[1] = i >> 8;
+        CHECK(secp256k1_schnorrsig_sign(data->ctx, &sig, msg, sk, NULL, NULL));
+    }
+}
+
+void bench_schnorrsig_verify(void* arg) {
+    bench_schnorrsig_data *data = (bench_schnorrsig_data *)arg;
+    size_t i;
+
+    for (i = 0; i < 1000; i++) {
+        secp256k1_xonly_pubkey pk;
+        CHECK(secp256k1_xonly_pubkey_parse(data->ctx, &pk, data->pk[i]) == 1);
+        CHECK(secp256k1_schnorrsig_verify(data->ctx, data->sigs[i], data->msgs[i], &pk));
+    }
+}
+
+void bench_schnorrsig_verify_n(void* arg) {
+    bench_schnorrsig_data *data = (bench_schnorrsig_data *)arg;
+    size_t i, j;
+    const secp256k1_xonly_pubkey **pk = (const secp256k1_xonly_pubkey **)malloc(data->n * sizeof(*pk));
+
+    CHECK(pk != NULL);
+    for (j = 0; j < MAX_SIGS/data->n; j++) {
+        for (i = 0; i < data->n; i++) {
+            secp256k1_xonly_pubkey *pk_nonconst = (secp256k1_xonly_pubkey *)malloc(sizeof(*pk_nonconst));
+            CHECK(secp256k1_xonly_pubkey_parse(data->ctx, pk_nonconst, data->pk[i]) == 1);
+            pk[i] = pk_nonconst;
+        }
+        CHECK(secp256k1_schnorrsig_verify_batch(data->ctx, data->scratch, data->sigs, data->msgs, pk, data->n));
+        for (i = 0; i < data->n; i++) {
+            free((void *)pk[i]);
+        }
+    }
+    free(pk);
+}
+
+int main(void) {
+    size_t i;
+    bench_schnorrsig_data data;
+
+    data.ctx = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY | SECP256K1_CONTEXT_SIGN);
+    data.scratch = secp256k1_scratch_space_create(data.ctx, 1024 * 1024 * 1024);
+    data.pk = (const unsigned char **)malloc(MAX_SIGS * sizeof(unsigned char *));
+    data.msgs = (const unsigned char **)malloc(MAX_SIGS * sizeof(unsigned char *));
+    data.sigs = (const secp256k1_schnorrsig **)malloc(MAX_SIGS * sizeof(secp256k1_schnorrsig *));
+
+    for (i = 0; i < MAX_SIGS; i++) {
+        unsigned char sk[32];
+        unsigned char *msg = (unsigned char *)malloc(32);
+        secp256k1_schnorrsig *sig = (secp256k1_schnorrsig *)malloc(sizeof(*sig));
+        unsigned char *pk_char = (unsigned char *)malloc(32);
+        secp256k1_xonly_pubkey pk;
+        msg[0] = sk[0] = i;
+        msg[1] = sk[1] = i >> 8;
+        msg[2] = sk[2] = i >> 16;
+        msg[3] = sk[3] = i >> 24;
+        memset(&msg[4], 'm', 28);
+        memset(&sk[4], 's', 28);
+
+        data.pk[i] = pk_char;
+        data.msgs[i] = msg;
+        data.sigs[i] = sig;
+
+        CHECK(secp256k1_xonly_pubkey_create(data.ctx, &pk, sk));
+        CHECK(secp256k1_xonly_pubkey_serialize(data.ctx, pk_char, &pk) == 1);
+        CHECK(secp256k1_schnorrsig_sign(data.ctx, sig, msg, sk, NULL, NULL));
+    }
+
+    run_benchmark("schnorrsig_sign", bench_schnorrsig_sign, NULL, NULL, (void *) &data, 10, 1000);
+    run_benchmark("schnorrsig_verify", bench_schnorrsig_verify, NULL, NULL, (void *) &data, 10, 1000);
+    for (i = 1; i <= MAX_SIGS; i *= 2) {
+        char name[64];
+        sprintf(name, "schnorrsig_batch_verify_%d", (int) i);
+
+        data.n = i;
+        run_benchmark(name, bench_schnorrsig_verify_n, NULL, NULL, (void *) &data, 3, MAX_SIGS);
+    }
+
+    for (i = 0; i < MAX_SIGS; i++) {
+        free((void *)data.pk[i]);
+        free((void *)data.msgs[i]);
+        free((void *)data.sigs[i]);
+    }
+    free(data.pk);
+    free(data.msgs);
+    free(data.sigs);
+
+    secp256k1_scratch_space_destroy(data.ctx, data.scratch);
+    secp256k1_context_destroy(data.ctx);
+    return 0;
+}
diff --git a/src/hash_impl.h b/src/hash_impl.h
index 782f97216c..1ab05cae1d 100644
--- a/src/hash_impl.h
+++ b/src/hash_impl.h
@@ -163,6 +163,19 @@ static void secp256k1_sha256_finalize(secp256k1_sha256 *hash, unsigned char *out
     memcpy(out32, (const unsigned char*)out, 32);
 }
 
+/* Initializes a sha256 struct and writes the 64 byte string
+ * SHA256(tag)||SHA256(tag) into it. */
+static void secp256k1_sha256_initialize_tagged(secp256k1_sha256 *hash, const unsigned char *tag, size_t taglen) {
+    unsigned char buf[32];
+    secp256k1_sha256_initialize(hash);
+    secp256k1_sha256_write(hash, tag, taglen);
+    secp256k1_sha256_finalize(hash, buf);
+
+    secp256k1_sha256_initialize(hash);
+    secp256k1_sha256_write(hash, buf, 32);
+    secp256k1_sha256_write(hash, buf, 32);
+}
+
 static void secp256k1_hmac_sha256_initialize(secp256k1_hmac_sha256 *hash, const unsigned char *key, size_t keylen) {
     size_t n;
     unsigned char rkey[64];
diff --git a/src/modules/schnorrsig/Makefile.am.include b/src/modules/schnorrsig/Makefile.am.include
new file mode 100644
index 0000000000..a82bafe43f
--- /dev/null
+++ b/src/modules/schnorrsig/Makefile.am.include
@@ -0,0 +1,8 @@
+include_HEADERS += include/secp256k1_schnorrsig.h
+noinst_HEADERS += src/modules/schnorrsig/main_impl.h
+noinst_HEADERS += src/modules/schnorrsig/tests_impl.h
+if USE_BENCHMARK
+noinst_PROGRAMS += bench_schnorrsig
+bench_schnorrsig_SOURCES = src/bench_schnorrsig.c
+bench_schnorrsig_LDADD = libsecp256k1.la $(SECP_LIBS) $(COMMON_LIB)
+endif
diff --git a/src/modules/schnorrsig/main_impl.h b/src/modules/schnorrsig/main_impl.h
new file mode 100644
index 0000000000..aff767ca73
--- /dev/null
+++ b/src/modules/schnorrsig/main_impl.h
@@ -0,0 +1,366 @@
+/**********************************************************************
+ * Copyright (c) 2018 Andrew Poelstra                                 *
+ * Distributed under the MIT software license, see the accompanying   *
+ * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
+ **********************************************************************/
+
+#ifndef _SECP256K1_MODULE_SCHNORRSIG_MAIN_
+#define _SECP256K1_MODULE_SCHNORRSIG_MAIN_
+
+#include "include/secp256k1.h"
+#include "include/secp256k1_schnorrsig.h"
+#include "hash.h"
+
+int secp256k1_schnorrsig_serialize(const secp256k1_context* ctx, unsigned char *out64, const secp256k1_schnorrsig* sig) {
+    (void) ctx;
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(out64 != NULL);
+    ARG_CHECK(sig != NULL);
+    memcpy(out64, sig->data, 64);
+    return 1;
+}
+
+int secp256k1_schnorrsig_parse(const secp256k1_context* ctx, secp256k1_schnorrsig* sig, const unsigned char *in64) {
+    (void) ctx;
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(sig != NULL);
+    ARG_CHECK(in64 != NULL);
+    memcpy(sig->data, in64, 64);
+    return 1;
+}
+
+/* Initializes SHA256 with fixed midstate. This midstate was computed by applying
+ * SHA256 to SHA256("BIPSchnorr")||SHA256("BIPSchnorr"). */
+static void secp256k1_schnorrsig_sha256_tagged(secp256k1_sha256 *sha) {
+    secp256k1_sha256_initialize(sha);
+    sha->s[0] = 0x048d9a59ul;
+    sha->s[1] = 0xfe39fb05ul;
+    sha->s[2] = 0x28479648ul;
+    sha->s[3] = 0xe4a660f9ul;
+    sha->s[4] = 0x814b9e66ul;
+    sha->s[5] = 0x0469e801ul;
+    sha->s[6] = 0x83909280ul;
+    sha->s[7] = 0xb329e454ul;
+    sha->bytes = 64;
+}
+
+int secp256k1_schnorrsig_sign(const secp256k1_context* ctx, secp256k1_schnorrsig *sig, const unsigned char *msg32, const unsigned char *seckey, secp256k1_nonce_function noncefp, void *ndata) {
+    secp256k1_scalar x;
+    secp256k1_scalar e;
+    secp256k1_scalar k;
+    secp256k1_gej pkj;
+    secp256k1_gej rj;
+    secp256k1_ge pk;
+    secp256k1_ge r;
+    secp256k1_sha256 sha;
+    int overflow;
+    unsigned char buf[32];
+    unsigned char seckey_tmp[32];
+
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
+    ARG_CHECK(sig != NULL);
+    ARG_CHECK(msg32 != NULL);
+    ARG_CHECK(seckey != NULL);
+
+    if (noncefp == NULL) {
+        noncefp = secp256k1_nonce_function_bipschnorr;
+    }
+    secp256k1_scalar_set_b32(&x, seckey, &overflow);
+    /* Fail if the secret key is invalid. */
+    if (overflow || secp256k1_scalar_is_zero(&x)) {
+        memset(sig, 0, sizeof(*sig));
+        return 0;
+    }
+
+    secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &pkj, &x);
+    secp256k1_ge_set_gej(&pk, &pkj);
+
+    /* Because we are signing for a x-only pubkey, the secret key is negated
+     * before signing if the point corresponding to the secret key is not
+     * positive. */
+    if (!secp256k1_fe_is_quad_var(&pk.y)) {
+        secp256k1_scalar_negate(&x, &x);
+    }
+
+    secp256k1_scalar_get_b32(seckey_tmp, &x);
+    if (!noncefp(buf, msg32, seckey_tmp, (unsigned char *) "BIPSchnorrDerive", (void*)ndata, 0)) {
+        memset(sig, 0, sizeof(*sig));
+        memset(seckey_tmp, 0, sizeof(seckey_tmp));
+        secp256k1_scalar_clear(&x);
+        return 0;
+    }
+    memset(seckey_tmp, 0, sizeof(seckey_tmp));
+
+    secp256k1_scalar_set_b32(&k, buf, NULL);
+    if (secp256k1_scalar_is_zero(&k)) {
+        memset(sig, 0, sizeof(*sig));
+        secp256k1_scalar_clear(&x);
+        return 0;
+    }
+
+    secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &rj, &k);
+    secp256k1_ge_set_gej(&r, &rj);
+
+    if (!secp256k1_fe_is_quad_var(&r.y)) {
+        secp256k1_scalar_negate(&k, &k);
+    }
+    secp256k1_fe_normalize(&r.x);
+    secp256k1_fe_get_b32(&sig->data[0], &r.x);
+
+    /* tagged hash(r.x, pk.x, msg32) */
+    secp256k1_schnorrsig_sha256_tagged(&sha);
+    secp256k1_sha256_write(&sha, &sig->data[0], 32);
+    secp256k1_fe_normalize(&pk.x);
+    secp256k1_fe_get_b32(buf, &pk.x);
+    secp256k1_sha256_write(&sha, buf, sizeof(buf));
+    secp256k1_sha256_write(&sha, msg32, 32);
+    secp256k1_sha256_finalize(&sha, buf);
+
+    secp256k1_scalar_set_b32(&e, buf, NULL);
+    secp256k1_scalar_mul(&e, &e, &x);
+    secp256k1_scalar_add(&e, &e, &k);
+
+    secp256k1_scalar_get_b32(&sig->data[32], &e);
+    secp256k1_scalar_clear(&k);
+    secp256k1_scalar_clear(&x);
+
+    return 1;
+}
+
+/* Helper function for verification and batch verification.
+ * Computes R = sG - eP. */
+static int secp256k1_schnorrsig_real_verify(const secp256k1_context* ctx, secp256k1_gej *rj, const secp256k1_scalar *s, const secp256k1_scalar *e, const secp256k1_xonly_pubkey *pk) {
+    secp256k1_scalar nege;
+    secp256k1_ge pkp;
+    secp256k1_gej pkj;
+
+    secp256k1_scalar_negate(&nege, e);
+
+    if (!secp256k1_pubkey_load(ctx, &pkp, (const secp256k1_pubkey *) pk)) {
+        return 0;
+    }
+    secp256k1_gej_set_ge(&pkj, &pkp);
+
+    /* rj =  s*G + (-e)*pkj */
+    secp256k1_ecmult(&ctx->ecmult_ctx, rj, &pkj, &nege, s);
+    return 1;
+}
+
+int secp256k1_schnorrsig_verify(const secp256k1_context* ctx, const secp256k1_schnorrsig *sig, const unsigned char *msg32, const secp256k1_xonly_pubkey *pk) {
+    secp256k1_scalar s;
+    secp256k1_scalar e;
+    secp256k1_gej rj;
+    secp256k1_fe rx;
+    secp256k1_sha256 sha;
+    unsigned char buf[32];
+    int overflow;
+
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
+    ARG_CHECK(sig != NULL);
+    ARG_CHECK(msg32 != NULL);
+    ARG_CHECK(pk != NULL);
+
+    if (!secp256k1_fe_set_b32(&rx, &sig->data[0])) {
+        return 0;
+    }
+
+    secp256k1_scalar_set_b32(&s, &sig->data[32], &overflow);
+    if (overflow) {
+        return 0;
+    }
+
+    secp256k1_schnorrsig_sha256_tagged(&sha);
+    secp256k1_sha256_write(&sha, &sig->data[0], 32);
+    secp256k1_xonly_pubkey_serialize(ctx, buf, pk);
+    secp256k1_sha256_write(&sha, buf, sizeof(buf));
+    secp256k1_sha256_write(&sha, msg32, 32);
+    secp256k1_sha256_finalize(&sha, buf);
+    secp256k1_scalar_set_b32(&e, buf, NULL);
+
+    if (!secp256k1_schnorrsig_real_verify(ctx, &rj, &s, &e, pk)
+        || !secp256k1_gej_has_quad_y_var(&rj) /* fails if rj is infinity */
+        || !secp256k1_gej_eq_x_var(&rx, &rj)) {
+        return 0;
+    }
+
+    return 1;
+}
+
+/* Data that is used by the batch verification ecmult callback */
+typedef struct {
+    const secp256k1_context *ctx;
+    /* Seed for the random number generator */
+    unsigned char chacha_seed[32];
+    /* Caches randomizers generated by the PRNG which returns two randomizers per call. Caching
+     * avoids having to call the PRNG twice as often. The very first randomizer will be set to 1 and
+     * the PRNG is called at every odd indexed schnorrsig to fill the cache. */
+    secp256k1_scalar randomizer_cache[2];
+    /* Signature, message, public key tuples to verify */
+    const secp256k1_schnorrsig *const *sig;
+    const unsigned char *const *msg32;
+    const secp256k1_xonly_pubkey *const *pk;
+    size_t n_sigs;
+} secp256k1_schnorrsig_verify_ecmult_context;
+
+/* Callback function which is called by ecmult_multi in order to convert the ecmult_context
+ * consisting of signature, message and public key tuples into scalars and points. */
+static int secp256k1_schnorrsig_verify_batch_ecmult_callback(secp256k1_scalar *sc, secp256k1_ge *pt, size_t idx, void *data) {
+    secp256k1_schnorrsig_verify_ecmult_context *ecmult_context = (secp256k1_schnorrsig_verify_ecmult_context *) data;
+
+    if (idx % 4 == 2) {
+        /* Every idx corresponds to a (scalar,point)-tuple. So this callback is called with 4
+         * consecutive tuples before we need to call the RNG for new randomizers:
+         * (-randomizer_cache[0], R1)
+         * (-randomizer_cache[0]*e1, P1)
+         * (-randomizer_cache[1], R2)
+         * (-randomizer_cache[1]*e2, P2) */
+        secp256k1_scalar_chacha20(&ecmult_context->randomizer_cache[0], &ecmult_context->randomizer_cache[1], ecmult_context->chacha_seed, idx / 4);
+    }
+
+    /* R */
+    if (idx % 2 == 0) {
+        secp256k1_fe rx;
+        *sc = ecmult_context->randomizer_cache[(idx / 2) % 2];
+        if (!secp256k1_fe_set_b32(&rx, &ecmult_context->sig[idx / 2]->data[0])) {
+            return 0;
+        }
+        if (!secp256k1_ge_set_xquad(pt, &rx)) {
+            return 0;
+        }
+    /* eP */
+    } else {
+        unsigned char buf[32];
+        secp256k1_sha256 sha;
+        secp256k1_schnorrsig_sha256_tagged(&sha);
+        secp256k1_sha256_write(&sha, &ecmult_context->sig[idx / 2]->data[0], 32);
+        secp256k1_xonly_pubkey_serialize(ecmult_context->ctx, buf, ecmult_context->pk[idx / 2]);
+        secp256k1_sha256_write(&sha, buf, sizeof(buf));
+        secp256k1_sha256_write(&sha, ecmult_context->msg32[idx / 2], 32);
+        secp256k1_sha256_finalize(&sha, buf);
+
+        secp256k1_scalar_set_b32(sc, buf, NULL);
+        secp256k1_scalar_mul(sc, sc, &ecmult_context->randomizer_cache[(idx / 2) % 2]);
+
+        if (!secp256k1_pubkey_load(ecmult_context->ctx, pt, (const secp256k1_pubkey *) ecmult_context->pk[idx / 2])) {
+            return 0;
+        }
+    }
+    return 1;
+}
+
+/** Helper function for batch verification. Hashes signature verification data into the
+ *  randomization seed and initializes ecmult_context.
+ *
+ *  Returns 1 if the randomizer was successfully initialized.
+ *
+ *  Args:    ctx: a secp256k1 context object
+ *  Out: ecmult_context: context for batch_ecmult_callback
+ *  In/Out   sha: an initialized sha256 object which hashes the schnorrsig input in order to get a
+ *                seed for the randomizer PRNG
+ *  In:      sig: array of signatures, or NULL if there are no signatures
+ *         msg32: array of messages, or NULL if there are no signatures
+ *            pk: array of public keys, or NULL if there are no signatures
+ *        n_sigs: number of signatures in above arrays (must be 0 if they are NULL)
+ */
+static int secp256k1_schnorrsig_verify_batch_init_randomizer(const secp256k1_context *ctx, secp256k1_schnorrsig_verify_ecmult_context *ecmult_context, secp256k1_sha256 *sha, const secp256k1_schnorrsig *const *sig, const unsigned char *const *msg32, const secp256k1_xonly_pubkey *const *pk, size_t n_sigs) {
+    size_t i;
+
+    if (n_sigs > 0) {
+        ARG_CHECK(sig != NULL);
+        ARG_CHECK(msg32 != NULL);
+        ARG_CHECK(pk != NULL);
+    }
+
+    for (i = 0; i < n_sigs; i++) {
+        unsigned char buf[33];
+        size_t buflen = sizeof(buf);
+        secp256k1_sha256_write(sha, sig[i]->data, 64);
+        secp256k1_sha256_write(sha, msg32[i], 32);
+        /* We use compressed serialization here. If we would use
+         * xonly_pubkey serialization and a user would wrongly memcpy
+         * normal secp256k1_pubkeys into xonly_pubkeys then the randomizer
+         * would be the same for two different pubkeys. */
+        secp256k1_ec_pubkey_serialize(ctx, buf, &buflen, (const secp256k1_pubkey *) pk[i], SECP256K1_EC_COMPRESSED);
+        secp256k1_sha256_write(sha, buf, buflen);
+    }
+    ecmult_context->ctx = ctx;
+    ecmult_context->sig = sig;
+    ecmult_context->msg32 = msg32;
+    ecmult_context->pk = pk;
+    ecmult_context->n_sigs = n_sigs;
+
+    return 1;
+}
+
+/** Helper function for batch verification. Sums the s part of all signatures multiplied by their
+ *  randomizer.
+ *
+ *  Returns 1 if s is successfully summed.
+ *
+ *  In/Out: s: the s part of the input sigs is added to this s argument
+ *  In:  chacha_seed: PRNG seed for computing randomizers
+ *        sig: array of signatures, or NULL if there are no signatures
+ *     n_sigs: number of signatures in above array (must be 0 if they are NULL)
+ */
+static int secp256k1_schnorrsig_verify_batch_sum_s(secp256k1_scalar *s, unsigned char *chacha_seed, const secp256k1_schnorrsig *const *sig, size_t n_sigs) {
+    secp256k1_scalar randomizer_cache[2];
+    size_t i;
+
+    secp256k1_scalar_set_int(&randomizer_cache[0], 1);
+    for (i = 0; i < n_sigs; i++) {
+        int overflow;
+        secp256k1_scalar term;
+        if (i % 2 == 1) {
+            secp256k1_scalar_chacha20(&randomizer_cache[0], &randomizer_cache[1], chacha_seed, i / 2);
+        }
+
+        secp256k1_scalar_set_b32(&term, &sig[i]->data[32], &overflow);
+        if (overflow) {
+            return 0;
+        }
+        secp256k1_scalar_mul(&term, &term, &randomizer_cache[i % 2]);
+        secp256k1_scalar_add(s, s, &term);
+    }
+    return 1;
+}
+
+/* schnorrsig batch verification.
+ * Seeds a random number generator with the inputs and derives a random number ai for every
+ * signature i. Fails if y-coordinate of any R is not a quadratic residue or if
+ * 0 != -(s1 + a2*s2 + ... + au*su)G + R1 + a2*R2 + ... + au*Ru + e1*P1 + (a2*e2)P2 + ... + (au*eu)Pu. */
+int secp256k1_schnorrsig_verify_batch(const secp256k1_context *ctx, secp256k1_scratch *scratch, const secp256k1_schnorrsig *const *sig, const unsigned char *const *msg32, const secp256k1_xonly_pubkey *const *pk, size_t n_sigs) {
+    secp256k1_schnorrsig_verify_ecmult_context ecmult_context;
+    secp256k1_sha256 sha;
+    secp256k1_scalar s;
+    secp256k1_gej rj;
+
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
+    ARG_CHECK(scratch != NULL);
+    /* Check that n_sigs is less than half of the maximum size_t value. This is necessary because
+     * the number of points given to ecmult_multi is 2*n_sigs. */
+    ARG_CHECK(n_sigs <= SIZE_MAX / 2);
+    /* Check that n_sigs is less than 2^31 to ensure the same behavior of this function on 32-bit
+     * and 64-bit platforms. */
+    ARG_CHECK(n_sigs < ((uint32_t)1 << 31));
+
+    secp256k1_sha256_initialize(&sha);
+    if (!secp256k1_schnorrsig_verify_batch_init_randomizer(ctx, &ecmult_context, &sha, sig, msg32, pk, n_sigs)) {
+        return 0;
+    }
+    secp256k1_sha256_finalize(&sha, ecmult_context.chacha_seed);
+    secp256k1_scalar_set_int(&ecmult_context.randomizer_cache[0], 1);
+
+    secp256k1_scalar_clear(&s);
+    if (!secp256k1_schnorrsig_verify_batch_sum_s(&s, ecmult_context.chacha_seed, sig, n_sigs)) {
+        return 0;
+    }
+    secp256k1_scalar_negate(&s, &s);
+
+    return secp256k1_ecmult_multi_var(&ctx->error_callback, &ctx->ecmult_ctx, scratch, &rj, &s, secp256k1_schnorrsig_verify_batch_ecmult_callback, (void *) &ecmult_context, 2 * n_sigs)
+            && secp256k1_gej_is_infinity(&rj);
+}
+
+#endif
diff --git a/src/modules/schnorrsig/tests_impl.h b/src/modules/schnorrsig/tests_impl.h
new file mode 100644
index 0000000000..f2502cffa4
--- /dev/null
+++ b/src/modules/schnorrsig/tests_impl.h
@@ -0,0 +1,708 @@
+/**********************************************************************
+ * Copyright (c) 2018 Andrew Poelstra                                 *
+ * Distributed under the MIT software license, see the accompanying   *
+ * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
+ **********************************************************************/
+
+#ifndef _SECP256K1_MODULE_SCHNORRSIG_TESTS_
+#define _SECP256K1_MODULE_SCHNORRSIG_TESTS_
+
+#include "secp256k1_schnorrsig.h"
+
+void test_schnorrsig_serialize(void) {
+    secp256k1_schnorrsig sig;
+    unsigned char in[64];
+    unsigned char out[64];
+
+    memset(in, 0x12, 64);
+    CHECK(secp256k1_schnorrsig_parse(ctx, &sig, in));
+    CHECK(secp256k1_schnorrsig_serialize(ctx, out, &sig));
+    CHECK(memcmp(in, out, 64) == 0);
+}
+
+void test_schnorrsig_api(secp256k1_scratch_space *scratch) {
+    unsigned char sk1[32];
+    unsigned char sk2[32];
+    unsigned char sk3[32];
+    unsigned char msg[32];
+    unsigned char sig64[64];
+    secp256k1_xonly_pubkey pk[3];
+    secp256k1_schnorrsig sig;
+    const secp256k1_schnorrsig *sigptr = &sig;
+    const unsigned char *msgptr = msg;
+    const secp256k1_xonly_pubkey *pkptr = &pk[0];
+
+    /** setup **/
+    secp256k1_context *none = secp256k1_context_create(SECP256K1_CONTEXT_NONE);
+    secp256k1_context *sign = secp256k1_context_create(SECP256K1_CONTEXT_SIGN);
+    secp256k1_context *vrfy = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY);
+    secp256k1_context *both = secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY);
+    int ecount;
+
+    secp256k1_context_set_error_callback(none, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_error_callback(sign, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_error_callback(vrfy, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_error_callback(both, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_illegal_callback(none, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_illegal_callback(sign, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_illegal_callback(vrfy, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_illegal_callback(both, counting_illegal_callback_fn, &ecount);
+
+    secp256k1_rand256(sk1);
+    secp256k1_rand256(sk2);
+    secp256k1_rand256(sk3);
+    secp256k1_rand256(msg);
+    CHECK(secp256k1_xonly_pubkey_create(ctx, &pk[0], sk1) == 1);
+    CHECK(secp256k1_xonly_pubkey_create(ctx, &pk[1], sk2) == 1);
+    CHECK(secp256k1_xonly_pubkey_create(ctx, &pk[2], sk3) == 1);
+
+    /** main test body **/
+    ecount = 0;
+    CHECK(secp256k1_schnorrsig_sign(none, &sig, msg, sk1, NULL, NULL) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_schnorrsig_sign(vrfy, &sig, msg, sk1, NULL, NULL) == 0);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_schnorrsig_sign(sign, &sig, msg, sk1, NULL, NULL) == 1);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_schnorrsig_sign(sign, NULL, msg, sk1, NULL, NULL) == 0);
+    CHECK(ecount == 3);
+    CHECK(secp256k1_schnorrsig_sign(sign, &sig, NULL, sk1, NULL, NULL) == 0);
+    CHECK(ecount == 4);
+    CHECK(secp256k1_schnorrsig_sign(sign, &sig, msg, NULL, NULL, NULL) == 0);
+    CHECK(ecount == 5);
+
+    ecount = 0;
+    CHECK(secp256k1_schnorrsig_serialize(none, sig64, &sig) == 1);
+    CHECK(ecount == 0);
+    CHECK(secp256k1_schnorrsig_serialize(none, NULL, &sig) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_schnorrsig_serialize(none, sig64, NULL) == 0);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_schnorrsig_parse(none, &sig, sig64) == 1);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_schnorrsig_parse(none, NULL, sig64) == 0);
+    CHECK(ecount == 3);
+    CHECK(secp256k1_schnorrsig_parse(none, &sig, NULL) == 0);
+    CHECK(ecount == 4);
+
+    ecount = 0;
+    CHECK(secp256k1_schnorrsig_verify(none, &sig, msg, &pk[0]) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_schnorrsig_verify(sign, &sig, msg, &pk[0]) == 0);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_schnorrsig_verify(vrfy, &sig, msg, &pk[0]) == 1);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_schnorrsig_verify(vrfy, NULL, msg, &pk[0]) == 0);
+    CHECK(ecount == 3);
+    CHECK(secp256k1_schnorrsig_verify(vrfy, &sig, NULL, &pk[0]) == 0);
+    CHECK(ecount == 4);
+    CHECK(secp256k1_schnorrsig_verify(vrfy, &sig, msg, NULL) == 0);
+    CHECK(ecount == 5);
+
+    ecount = 0;
+    CHECK(secp256k1_schnorrsig_verify_batch(none, scratch, &sigptr, &msgptr, &pkptr, 1) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_schnorrsig_verify_batch(sign, scratch, &sigptr, &msgptr, &pkptr, 1) == 0);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_schnorrsig_verify_batch(vrfy, scratch, &sigptr, &msgptr, &pkptr, 1) == 1);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_schnorrsig_verify_batch(vrfy, scratch, NULL, NULL, NULL, 0) == 1);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_schnorrsig_verify_batch(vrfy, scratch, NULL, &msgptr, &pkptr, 1) == 0);
+    CHECK(ecount == 3);
+    CHECK(secp256k1_schnorrsig_verify_batch(vrfy, scratch, &sigptr, NULL, &pkptr, 1) == 0);
+    CHECK(ecount == 4);
+    CHECK(secp256k1_schnorrsig_verify_batch(vrfy, scratch, &sigptr, &msgptr, NULL, 1) == 0);
+    CHECK(ecount == 5);
+    CHECK(secp256k1_schnorrsig_verify_batch(vrfy, scratch, &sigptr, &msgptr, &pkptr, (size_t)1 << (sizeof(size_t)*8-1)) == 0);
+    CHECK(ecount == 6);
+    CHECK(secp256k1_schnorrsig_verify_batch(vrfy, scratch, &sigptr, &msgptr, &pkptr, (uint32_t)1 << 31) == 0);
+    CHECK(ecount == 7);
+
+    secp256k1_context_destroy(none);
+    secp256k1_context_destroy(sign);
+    secp256k1_context_destroy(vrfy);
+    secp256k1_context_destroy(both);
+}
+
+/* Checks that hash initialized by secp256k1_musig_sha256_tagged has the
+ * expected state. */
+void test_schnorrsig_sha256_tagged(void) {
+    char tag[10] = "BIPSchnorr";
+    secp256k1_sha256 sha;
+    secp256k1_sha256 sha_optimized;
+
+    secp256k1_sha256_initialize_tagged(&sha, (unsigned char *) tag, sizeof(tag));
+    secp256k1_schnorrsig_sha256_tagged(&sha_optimized);
+    test_sha256_eq(&sha, &sha_optimized);
+}
+
+/* Helper function for schnorrsig_bip_vectors
+ * Signs the message and checks that it's the same as expected_sig. */
+void test_schnorrsig_bip_vectors_check_signing(const unsigned char *sk, const unsigned char *pk_serialized, const unsigned char *msg, const unsigned char *expected_sig) {
+    secp256k1_schnorrsig sig;
+    unsigned char serialized_sig[64];
+    secp256k1_xonly_pubkey pk;
+
+    CHECK(secp256k1_schnorrsig_sign(ctx, &sig, msg, sk, NULL, NULL));
+    CHECK(secp256k1_schnorrsig_serialize(ctx, serialized_sig, &sig));
+    CHECK(memcmp(serialized_sig, expected_sig, 64) == 0);
+
+    CHECK(secp256k1_xonly_pubkey_parse(ctx, &pk, pk_serialized));
+    CHECK(secp256k1_schnorrsig_verify(ctx, &sig, msg, &pk));
+}
+
+/* Helper function for schnorrsig_bip_vectors
+ * Checks that both verify and verify_batch return the same value as expected. */
+void test_schnorrsig_bip_vectors_check_verify(secp256k1_scratch_space *scratch, const unsigned char *pk_serialized, const unsigned char *msg32, const unsigned char *sig_serialized, int expected) {
+    const unsigned char *msg_arr[1];
+    const secp256k1_schnorrsig *sig_arr[1];
+    const secp256k1_xonly_pubkey *pk_arr[1];
+    secp256k1_xonly_pubkey pk;
+    secp256k1_schnorrsig sig;
+
+    CHECK(secp256k1_xonly_pubkey_parse(ctx, &pk, pk_serialized));
+    CHECK(secp256k1_schnorrsig_parse(ctx, &sig, sig_serialized));
+
+    sig_arr[0] = &sig;
+    msg_arr[0] = msg32;
+    pk_arr[0] = &pk;
+
+    CHECK(expected == secp256k1_schnorrsig_verify(ctx, &sig, msg32, &pk));
+    CHECK(expected == secp256k1_schnorrsig_verify_batch(ctx, scratch, sig_arr, msg_arr, pk_arr, 1));
+}
+
+/* Test vectors according to BIP-schnorr
+ * (https://github.com/sipa/bips/blob/775cb2fd903cbfe459081fda49ada744ef3139be/bip-schnorr/test-vectors.csv).
+ */
+void test_schnorrsig_bip_vectors(secp256k1_scratch_space *scratch) {
+    {
+        /* Test vector 0 */
+        const unsigned char sk[32] = {
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01
+        };
+        const unsigned char pk[32] = {
+            0x79, 0xBE, 0x66, 0x7E, 0xF9, 0xDC, 0xBB, 0xAC,
+            0x55, 0xA0, 0x62, 0x95, 0xCE, 0x87, 0x0B, 0x07,
+            0x02, 0x9B, 0xFC, 0xDB, 0x2D, 0xCE, 0x28, 0xD9,
+            0x59, 0xF2, 0x81, 0x5B, 0x16, 0xF8, 0x17, 0x98
+        };
+        const unsigned char msg[32] = {
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+        };
+        const unsigned char sig[64] = {
+            0x52, 0x8F, 0x74, 0x57, 0x93, 0xE8, 0x47, 0x2C,
+            0x03, 0x29, 0x74, 0x2A, 0x46, 0x3F, 0x59, 0xE5,
+            0x8F, 0x3A, 0x3F, 0x1A, 0x4A, 0xC0, 0x9C, 0x28,
+            0xF6, 0xF8, 0x51, 0x4D, 0x4D, 0x03, 0x22, 0xA2,
+            0x58, 0xBD, 0x08, 0x39, 0x8F, 0x82, 0xCF, 0x67,
+            0xB8, 0x12, 0xAB, 0x2C, 0x77, 0x17, 0xCE, 0x56,
+            0x6F, 0x87, 0x7C, 0x2F, 0x87, 0x95, 0xC8, 0x46,
+            0x14, 0x69, 0x78, 0xE8, 0xF0, 0x47, 0x82, 0xAE
+        };
+        test_schnorrsig_bip_vectors_check_signing(sk, pk, msg, sig);
+        test_schnorrsig_bip_vectors_check_verify(scratch, pk, msg, sig, 1);
+    }
+    {
+        /* Test vector 1 */
+        const unsigned char sk[32] = {
+            0xB7, 0xE1, 0x51, 0x62, 0x8A, 0xED, 0x2A, 0x6A,
+            0xBF, 0x71, 0x58, 0x80, 0x9C, 0xF4, 0xF3, 0xC7,
+            0x62, 0xE7, 0x16, 0x0F, 0x38, 0xB4, 0xDA, 0x56,
+            0xA7, 0x84, 0xD9, 0x04, 0x51, 0x90, 0xCF, 0xEF
+        };
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0x66, 0x7C, 0x2F, 0x77, 0x8E, 0x06, 0x16, 0xE6,
+            0x11, 0xBD, 0x0C, 0x14, 0xB8, 0xA6, 0x00, 0xC5,
+            0x88, 0x45, 0x51, 0x70, 0x1A, 0x94, 0x9E, 0xF0,
+            0xEB, 0xFD, 0x72, 0xD4, 0x52, 0xD6, 0x4E, 0x84,
+            0x41, 0x60, 0xBC, 0xFC, 0x3F, 0x46, 0x6E, 0xCB,
+            0x8F, 0xAC, 0xD1, 0x9A, 0xDE, 0x57, 0xD8, 0x69,
+            0x9D, 0x74, 0xE7, 0x20, 0x7D, 0x78, 0xC6, 0xAE,
+            0xDC, 0x37, 0x99, 0xB5, 0x2A, 0x8E, 0x05, 0x98
+        };
+        test_schnorrsig_bip_vectors_check_signing(sk, pk, msg, sig);
+        test_schnorrsig_bip_vectors_check_verify(scratch, pk, msg, sig, 1);
+    }
+    {
+        /* Test vector 2 */
+        const unsigned char sk[32] = {
+            0xC9, 0x0F, 0xDA, 0xA2, 0x21, 0x68, 0xC2, 0x34,
+            0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
+            0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74,
+            0x02, 0x0B, 0xBE, 0xA6, 0x3B, 0x14, 0xE5, 0xC9
+        };
+        const unsigned char pk[32] = {
+            0xDD, 0x30, 0x8A, 0xFE, 0xC5, 0x77, 0x7E, 0x13,
+            0x12, 0x1F, 0xA7, 0x2B, 0x9C, 0xC1, 0xB7, 0xCC,
+            0x01, 0x39, 0x71, 0x53, 0x09, 0xB0, 0x86, 0xC9,
+            0x60, 0xE1, 0x8F, 0xD9, 0x69, 0x77, 0x4E, 0xB8
+        };
+        const unsigned char msg[32] = {
+            0x5E, 0x2D, 0x58, 0xD8, 0xB3, 0xBC, 0xDF, 0x1A,
+            0xBA, 0xDE, 0xC7, 0x82, 0x90, 0x54, 0xF9, 0x0D,
+            0xDA, 0x98, 0x05, 0xAA, 0xB5, 0x6C, 0x77, 0x33,
+            0x30, 0x24, 0xB9, 0xD0, 0xA5, 0x08, 0xB7, 0x5C
+        };
+        const unsigned char sig[64] = {
+            0x2D, 0x94, 0x1B, 0x38, 0xE3, 0x26, 0x24, 0xBF,
+            0x0A, 0xC7, 0x66, 0x9C, 0x09, 0x71, 0xB9, 0x90,
+            0x99, 0x4A, 0xF6, 0xF9, 0xB1, 0x84, 0x26, 0xBF,
+            0x4F, 0x4E, 0x7E, 0xC1, 0x0E, 0x6C, 0xDF, 0x38,
+            0x6C, 0xF6, 0x46, 0xC6, 0xDD, 0xAF, 0xCF, 0xA7,
+            0xF1, 0x99, 0x3E, 0xEB, 0x2E, 0x4D, 0x66, 0x41,
+            0x6A, 0xEA, 0xD1, 0xDD, 0xAE, 0x2F, 0x22, 0xD6,
+            0x3C, 0xAD, 0x90, 0x14, 0x12, 0xD1, 0x16, 0xC6
+        };
+        test_schnorrsig_bip_vectors_check_signing(sk, pk, msg, sig);
+        test_schnorrsig_bip_vectors_check_verify(scratch, pk, msg, sig, 1);
+    }
+    {
+        /* Test vector 3 */
+        const unsigned char sk[32] = {
+            0x0B, 0x43, 0x2B, 0x26, 0x77, 0x93, 0x73, 0x81,
+            0xAE, 0xF0, 0x5B, 0xB0, 0x2A, 0x66, 0xEC, 0xD0,
+            0x12, 0x77, 0x30, 0x62, 0xCF, 0x3F, 0xA2, 0x54,
+            0x9E, 0x44, 0xF5, 0x8E, 0xD2, 0x40, 0x17, 0x10
+        };
+        const unsigned char pk[32] = {
+            0x25, 0xD1, 0xDF, 0xF9, 0x51, 0x05, 0xF5, 0x25,
+            0x3C, 0x40, 0x22, 0xF6, 0x28, 0xA9, 0x96, 0xAD,
+            0x3A, 0x0D, 0x95, 0xFB, 0xF2, 0x1D, 0x46, 0x8A,
+            0x1B, 0x33, 0xF8, 0xC1, 0x60, 0xD8, 0xF5, 0x17
+        };
+        const unsigned char msg[32] = {
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
+        };
+        const unsigned char sig[64] = {
+            0x8B, 0xD2, 0xC1, 0x16, 0x04, 0xB0, 0xA8, 0x7A,
+            0x44, 0x3F, 0xCC, 0x2E, 0x5D, 0x90, 0xE5, 0x32,
+            0x8F, 0x93, 0x41, 0x61, 0xB1, 0x88, 0x64, 0xFB,
+            0x48, 0xCE, 0x10, 0xCB, 0x59, 0xB4, 0x5F, 0xB9,
+            0xB5, 0xB2, 0xA0, 0xF1, 0x29, 0xBD, 0x88, 0xF5,
+            0xBD, 0xC0, 0x5D, 0x5C, 0x21, 0xE5, 0xC5, 0x71,
+            0x76, 0xB9, 0x13, 0x00, 0x23, 0x35, 0x78, 0x4F,
+            0x97, 0x77, 0xA2, 0x4B, 0xD3, 0x17, 0xCD, 0x36
+        };
+        test_schnorrsig_bip_vectors_check_signing(sk, pk, msg, sig);
+        test_schnorrsig_bip_vectors_check_verify(scratch, pk, msg, sig, 1);
+    }
+    {
+        /* Test vector 4 */
+        const unsigned char pk[32] = {
+            0xD6, 0x9C, 0x35, 0x09, 0xBB, 0x99, 0xE4, 0x12,
+            0xE6, 0x8B, 0x0F, 0xE8, 0x54, 0x4E, 0x72, 0x83,
+            0x7D, 0xFA, 0x30, 0x74, 0x6D, 0x8B, 0xE2, 0xAA,
+            0x65, 0x97, 0x5F, 0x29, 0xD2, 0x2D, 0xC7, 0xB9
+        };
+        const unsigned char msg[32] = {
+            0x4D, 0xF3, 0xC3, 0xF6, 0x8F, 0xCC, 0x83, 0xB2,
+            0x7E, 0x9D, 0x42, 0xC9, 0x04, 0x31, 0xA7, 0x24,
+            0x99, 0xF1, 0x78, 0x75, 0xC8, 0x1A, 0x59, 0x9B,
+            0x56, 0x6C, 0x98, 0x89, 0xB9, 0x69, 0x67, 0x03
+        };
+        const unsigned char sig[64] = {
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x3B, 0x78, 0xCE, 0x56, 0x3F,
+            0x89, 0xA0, 0xED, 0x94, 0x14, 0xF5, 0xAA, 0x28,
+            0xAD, 0x0D, 0x96, 0xD6, 0x79, 0x5F, 0x9C, 0x63,
+            0xEE, 0x37, 0x4A, 0xC7, 0xFA, 0xE9, 0x27, 0xD3,
+            0x34, 0xCC, 0xB1, 0x90, 0xF6, 0xFB, 0x8F, 0xD2,
+            0x7A, 0x2D, 0xDC, 0x63, 0x9C, 0xCE, 0xE4, 0x6D,
+            0x43, 0xF1, 0x13, 0xA4, 0x03, 0x5A, 0x2C, 0x7F
+        };
+        test_schnorrsig_bip_vectors_check_verify(scratch, pk, msg, sig, 1);
+    }
+    {
+        /* Test vector 5 */
+        const unsigned char pk[32] = {
+            0xEE, 0xFD, 0xEA, 0x4C, 0xDB, 0x67, 0x77, 0x50,
+            0xA4, 0x20, 0xFE, 0xE8, 0x07, 0xEA, 0xCF, 0x21,
+            0xEB, 0x98, 0x98, 0xAE, 0x79, 0xB9, 0x76, 0x87,
+            0x66, 0xE4, 0xFA, 0xA0, 0x4A, 0x2D, 0x4A, 0x34
+        };
+        secp256k1_xonly_pubkey pk_parsed;
+        /* No need to check the signature of the test vector as parsing the pubkey already fails */
+        CHECK(!secp256k1_xonly_pubkey_parse(ctx, &pk_parsed, pk));
+    }
+    {
+        /* Test vector 6 */
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0xF9, 0x30, 0x8A, 0x01, 0x92, 0x58, 0xC3, 0x10,
+            0x49, 0x34, 0x4F, 0x85, 0xF8, 0x9D, 0x52, 0x29,
+            0xB5, 0x31, 0xC8, 0x45, 0x83, 0x6F, 0x99, 0xB0,
+            0x86, 0x01, 0xF1, 0x13, 0xBC, 0xE0, 0x36, 0xF9,
+            0x93, 0x55, 0x54, 0xD1, 0xAA, 0x5F, 0x03, 0x74,
+            0xE5, 0xCD, 0xAA, 0xCB, 0x39, 0x25, 0x03, 0x5C,
+            0x7C, 0x16, 0x9B, 0x27, 0xC4, 0x42, 0x6D, 0xF0,
+            0xA6, 0xB1, 0x9A, 0xF3, 0xBA, 0xEA, 0xB1, 0x38
+        };
+        test_schnorrsig_bip_vectors_check_verify(scratch, pk, msg, sig, 0);
+    }
+    {
+        /* Test vector 7 */
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0x10, 0xAC, 0x49, 0xA6, 0xA2, 0xEB, 0xF6, 0x04,
+            0x18, 0x9C, 0x5F, 0x40, 0xFC, 0x75, 0xAF, 0x2D,
+            0x42, 0xD7, 0x7D, 0xE9, 0xA2, 0x78, 0x27, 0x09,
+            0xB1, 0xEB, 0x4E, 0xAF, 0x1C, 0xFE, 0x91, 0x08,
+            0xD7, 0x00, 0x3B, 0x70, 0x3A, 0x34, 0x99, 0xD5,
+            0xE2, 0x95, 0x29, 0xD3, 0x9B, 0xA0, 0x40, 0xA4,
+            0x49, 0x55, 0x12, 0x71, 0x40, 0xF8, 0x1A, 0x8A,
+            0x89, 0xA9, 0x6F, 0x99, 0x2A, 0xC0, 0xFE, 0x79
+        };
+        test_schnorrsig_bip_vectors_check_verify(scratch, pk, msg, sig, 0);
+    }
+    {
+        /* Test vector 8 */
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0x66, 0x7C, 0x2F, 0x77, 0x8E, 0x06, 0x16, 0xE6,
+            0x11, 0xBD, 0x0C, 0x14, 0xB8, 0xA6, 0x00, 0xC5,
+            0x88, 0x45, 0x51, 0x70, 0x1A, 0x94, 0x9E, 0xF0,
+            0xEB, 0xFD, 0x72, 0xD4, 0x52, 0xD6, 0x4E, 0x84,
+            0xBE, 0x9F, 0x43, 0x03, 0xC0, 0xB9, 0x91, 0x34,
+            0x70, 0x53, 0x2E, 0x65, 0x21, 0xA8, 0x27, 0x95,
+            0x1D, 0x39, 0xF5, 0xC6, 0x31, 0xCF, 0xD9, 0x8C,
+            0xE3, 0x9A, 0xC4, 0xD7, 0xA5, 0xA8, 0x3B, 0xA9
+        };
+        test_schnorrsig_bip_vectors_check_verify(scratch, pk, msg, sig, 0);
+    }
+    {
+        /* Test vector 9 */
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x99, 0xD2, 0xF0, 0xEB, 0xC2, 0x99, 0x68, 0x08,
+            0x20, 0x86, 0x33, 0xCD, 0x99, 0x26, 0xBF, 0x7E,
+            0xC3, 0xDA, 0xB7, 0x3D, 0xAA, 0xD3, 0x6E, 0x85,
+            0xB3, 0x04, 0x0A, 0x69, 0x8E, 0x6D, 0x1C, 0xE0
+        };
+        test_schnorrsig_bip_vectors_check_verify(scratch, pk, msg, sig, 0);
+    }
+    {
+        /* Test vector 10 */
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
+            0x24, 0xE8, 0x1D, 0x89, 0xF0, 0x13, 0x04, 0x69,
+            0x5C, 0xE9, 0x43, 0xF7, 0xD5, 0xEB, 0xD0, 0x0E,
+            0xF7, 0x26, 0xA0, 0x86, 0x4B, 0x4F, 0xF3, 0x38,
+            0x95, 0xB4, 0xE8, 0x6B, 0xEA, 0xDC, 0x54, 0x56
+        };
+        test_schnorrsig_bip_vectors_check_verify(scratch, pk, msg, sig, 0);
+    }
+    {
+        /* Test vector 11 */
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0x4A, 0x29, 0x8D, 0xAC, 0xAE, 0x57, 0x39, 0x5A,
+            0x15, 0xD0, 0x79, 0x5D, 0xDB, 0xFD, 0x1D, 0xCB,
+            0x56, 0x4D, 0xA8, 0x2B, 0x0F, 0x26, 0x9B, 0xC7,
+            0x0A, 0x74, 0xF8, 0x22, 0x04, 0x29, 0xBA, 0x1D,
+            0x41, 0x60, 0xBC, 0xFC, 0x3F, 0x46, 0x6E, 0xCB,
+            0x8F, 0xAC, 0xD1, 0x9A, 0xDE, 0x57, 0xD8, 0x69,
+            0x9D, 0x74, 0xE7, 0x20, 0x7D, 0x78, 0xC6, 0xAE,
+            0xDC, 0x37, 0x99, 0xB5, 0x2A, 0x8E, 0x05, 0x98
+        };
+        test_schnorrsig_bip_vectors_check_verify(scratch, pk, msg, sig, 0);
+    }
+    {
+        /* Test vector 12 */
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x13, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFE, 0xFF, 0xFF, 0xFC, 0x2F,
+            0x41, 0x60, 0xBC, 0xFC, 0x3F, 0x46, 0x6E, 0xCB,
+            0x8F, 0xAC, 0xD1, 0x9A, 0xDE, 0x57, 0xD8, 0x69,
+            0x9D, 0x74, 0xE7, 0x20, 0x7D, 0x78, 0xC6, 0xAE,
+            0xDC, 0x37, 0x99, 0xB5, 0x2A, 0x8E, 0x05, 0x98
+        };
+        test_schnorrsig_bip_vectors_check_verify(scratch, pk, msg, sig, 0);
+    }
+    {
+        /* Test vector 13 */
+        const unsigned char pk[32] = {
+            0xDF, 0xF1, 0xD7, 0x7F, 0x2A, 0x67, 0x1C, 0x5F,
+            0x36, 0x18, 0x37, 0x26, 0xDB, 0x23, 0x41, 0xBE,
+            0x58, 0xFE, 0xAE, 0x1D, 0xA2, 0xDE, 0xCE, 0xD8,
+            0x43, 0x24, 0x0F, 0x7B, 0x50, 0x2B, 0xA6, 0x59
+        };
+        const unsigned char msg[32] = {
+            0x24, 0x3F, 0x6A, 0x88, 0x85, 0xA3, 0x08, 0xD3,
+            0x14, 0x19, 0x8A, 0x2E, 0x03, 0x70, 0x73, 0x44,
+            0xA4, 0x09, 0x38, 0x22, 0x29, 0x9F, 0x31, 0xD0,
+            0x08, 0x2E, 0xFA, 0x98, 0xEC, 0x4E, 0x6C, 0x89
+        };
+        const unsigned char sig[64] = {
+            0x66, 0x7C, 0x2F, 0x77, 0x8E, 0x06, 0x16, 0xE6,
+            0x11, 0xBD, 0x0C, 0x14, 0xB8, 0xA6, 0x00, 0xC5,
+            0x88, 0x45, 0x51, 0x70, 0x1A, 0x94, 0x9E, 0xF0,
+            0xEB, 0xFD, 0x72, 0xD4, 0x52, 0xD6, 0x4E, 0x84,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFE,
+            0xBA, 0xAE, 0xDC, 0xE6, 0xAF, 0x48, 0xA0, 0x3B,
+            0xBF, 0xD2, 0x5E, 0x8C, 0xD0, 0x36, 0x41, 0x41
+        };
+        test_schnorrsig_bip_vectors_check_verify(scratch, pk, msg, sig, 0);
+    }
+}
+
+/* Nonce function that returns constant 0 */
+static int nonce_function_failing(unsigned char *nonce32, const unsigned char *msg32, const unsigned char *key32, const unsigned char *algo16, void *data, unsigned int counter) {
+    (void) msg32;
+    (void) key32;
+    (void) algo16;
+    (void) data;
+    (void) counter;
+    (void) nonce32;
+    return 0;
+}
+
+/* Nonce function that sets nonce to 0 */
+static int nonce_function_0(unsigned char *nonce32, const unsigned char *msg32, const unsigned char *key32, const unsigned char *algo16, void *data, unsigned int counter) {
+    (void) msg32;
+    (void) key32;
+    (void) algo16;
+    (void) data;
+    (void) counter;
+
+    memset(nonce32, 0, 32);
+    return 1;
+}
+
+void test_schnorrsig_sign(void) {
+    unsigned char sk[32];
+    const unsigned char msg[32] = "this is a msg for a schnorrsig..";
+    secp256k1_schnorrsig sig;
+
+    memset(sk, 23, sizeof(sk));
+    CHECK(secp256k1_schnorrsig_sign(ctx, &sig, msg, sk, NULL, NULL) == 1);
+
+    /* Overflowing secret key */
+    memset(sk, 0xFF, sizeof(sk));
+    CHECK(secp256k1_schnorrsig_sign(ctx, &sig, msg, sk, NULL, NULL) == 0);
+    memset(sk, 23, sizeof(sk));
+
+    CHECK(secp256k1_schnorrsig_sign(ctx, &sig, msg, sk, nonce_function_failing, NULL) == 0);
+    CHECK(secp256k1_schnorrsig_sign(ctx, &sig, msg, sk, nonce_function_0, NULL) == 0);
+}
+
+#define N_SIGS  200
+/* Creates N_SIGS valid signatures and verifies them with verify and verify_batch. Then flips some
+ * bits and checks that verification now fails. */
+void test_schnorrsig_sign_verify(secp256k1_scratch_space *scratch) {
+    const unsigned char sk[32] = "shhhhhhhh! this key is a secret.";
+    unsigned char msg[N_SIGS][32];
+    secp256k1_schnorrsig sig[N_SIGS];
+    size_t i;
+    const secp256k1_schnorrsig *sig_arr[N_SIGS];
+    const unsigned char *msg_arr[N_SIGS];
+    const secp256k1_xonly_pubkey *pk_arr[N_SIGS];
+    secp256k1_xonly_pubkey pk;
+
+    CHECK(secp256k1_xonly_pubkey_create(ctx, &pk, sk));
+
+    CHECK(secp256k1_schnorrsig_verify_batch(ctx, scratch, NULL, NULL, NULL, 0));
+
+    for (i = 0; i < N_SIGS; i++) {
+        secp256k1_rand256(msg[i]);
+        CHECK(secp256k1_schnorrsig_sign(ctx, &sig[i], msg[i], sk, NULL, NULL));
+        CHECK(secp256k1_schnorrsig_verify(ctx, &sig[i], msg[i], &pk));
+        sig_arr[i] = &sig[i];
+        msg_arr[i] = msg[i];
+        pk_arr[i] = &pk;
+    }
+
+    CHECK(secp256k1_schnorrsig_verify_batch(ctx, scratch, sig_arr, msg_arr, pk_arr, 1));
+    CHECK(secp256k1_schnorrsig_verify_batch(ctx, scratch, sig_arr, msg_arr, pk_arr, 2));
+    CHECK(secp256k1_schnorrsig_verify_batch(ctx, scratch, sig_arr, msg_arr, pk_arr, 4));
+    CHECK(secp256k1_schnorrsig_verify_batch(ctx, scratch, sig_arr, msg_arr, pk_arr, N_SIGS));
+
+    {
+        /* Flip a few bits in the signature and in the message and check that
+         * verify and verify_batch fail */
+        size_t sig_idx = secp256k1_rand_int(4);
+        size_t byte_idx = secp256k1_rand_int(32);
+        unsigned char xorbyte = secp256k1_rand_int(254)+1;
+        sig[sig_idx].data[byte_idx] ^= xorbyte;
+        CHECK(!secp256k1_schnorrsig_verify(ctx, &sig[sig_idx], msg[sig_idx], &pk));
+        CHECK(!secp256k1_schnorrsig_verify_batch(ctx, scratch, sig_arr, msg_arr, pk_arr, 4));
+        sig[sig_idx].data[byte_idx] ^= xorbyte;
+
+        byte_idx = secp256k1_rand_int(32);
+        sig[sig_idx].data[32+byte_idx] ^= xorbyte;
+        CHECK(!secp256k1_schnorrsig_verify(ctx, &sig[sig_idx], msg[sig_idx], &pk));
+        CHECK(!secp256k1_schnorrsig_verify_batch(ctx, scratch, sig_arr, msg_arr, pk_arr, 4));
+        sig[sig_idx].data[32+byte_idx] ^= xorbyte;
+
+        byte_idx = secp256k1_rand_int(32);
+        msg[sig_idx][byte_idx] ^= xorbyte;
+        CHECK(!secp256k1_schnorrsig_verify(ctx, &sig[sig_idx], msg[sig_idx], &pk));
+        CHECK(!secp256k1_schnorrsig_verify_batch(ctx, scratch, sig_arr, msg_arr, pk_arr, 4));
+        msg[sig_idx][byte_idx] ^= xorbyte;
+
+        /* Check that above bitflips have been reversed correctly */
+        CHECK(secp256k1_schnorrsig_verify(ctx, &sig[sig_idx], msg[sig_idx], &pk));
+        CHECK(secp256k1_schnorrsig_verify_batch(ctx, scratch, sig_arr, msg_arr, pk_arr, 4));
+    }
+}
+#undef N_SIGS
+
+void test_schnorrsig_taproot(void) {
+    unsigned char sk[32];
+    secp256k1_xonly_pubkey internal_pk;
+    unsigned char internal_pk_bytes[32];
+    secp256k1_xonly_pubkey output_pk;
+    unsigned char output_pk_bytes[32];
+    unsigned char tweak[32];
+    int is_positive;
+    unsigned char msg[32];
+    secp256k1_schnorrsig sig;
+
+    /* Create output key */
+    secp256k1_rand256(sk);
+    CHECK(secp256k1_xonly_pubkey_create(ctx, &internal_pk, sk) == 1);
+    memset(tweak, 1, sizeof(tweak));
+    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &is_positive, &internal_pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_serialize(ctx, output_pk_bytes, &output_pk) == 1);
+
+    /* Key spend */
+    secp256k1_rand256(msg);
+    CHECK(secp256k1_xonly_privkey_tweak_add(ctx, sk, tweak) == 1);
+    CHECK(secp256k1_schnorrsig_sign(ctx, &sig, msg, sk, NULL, NULL) == 1);
+    /* Verify key spend */
+    CHECK(secp256k1_xonly_pubkey_parse(ctx, &output_pk, output_pk_bytes) == 1);
+    CHECK(secp256k1_schnorrsig_verify(ctx, &sig, msg, &output_pk) == 1);
+
+    /* Script spend */
+    CHECK(secp256k1_xonly_pubkey_serialize(ctx, internal_pk_bytes, &internal_pk) == 1);
+    /* Verify script spend */
+    CHECK(secp256k1_xonly_pubkey_parse(ctx, &output_pk, output_pk_bytes) == 1);
+    CHECK(secp256k1_xonly_pubkey_parse(ctx, &internal_pk, internal_pk_bytes) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_verify(ctx, &output_pk, is_positive, &internal_pk, tweak) == 1);
+}
+
+void run_schnorrsig_tests(void) {
+    secp256k1_scratch_space *scratch = secp256k1_scratch_space_create(ctx, 1024 * 1024);
+
+    test_schnorrsig_serialize();
+    test_schnorrsig_api(scratch);
+    test_schnorrsig_sha256_tagged();
+    test_schnorrsig_bip_vectors(scratch);
+    test_schnorrsig_sign();
+    test_schnorrsig_sign_verify(scratch);
+    test_schnorrsig_taproot();
+
+    secp256k1_scratch_space_destroy(ctx, scratch);
+}
+
+#endif
diff --git a/src/scalar.h b/src/scalar.h
index 59304cb66e..640693a5e3 100644
--- a/src/scalar.h
+++ b/src/scalar.h
@@ -103,4 +103,7 @@ static void secp256k1_scalar_split_lambda(secp256k1_scalar *r1, secp256k1_scalar
 /** Multiply a and b (without taking the modulus!), divide by 2**shift, and round to the nearest integer. Shift must be at least 256. */
 static void secp256k1_scalar_mul_shift_var(secp256k1_scalar *r, const secp256k1_scalar *a, const secp256k1_scalar *b, unsigned int shift);
 
+/** Generate two scalars from a 32-byte seed and an integer using the chacha20 stream cipher */
+static void secp256k1_scalar_chacha20(secp256k1_scalar *r1, secp256k1_scalar *r2, const unsigned char *seed, uint64_t idx);
+
 #endif /* SECP256K1_SCALAR_H */
diff --git a/src/scalar_4x64_impl.h b/src/scalar_4x64_impl.h
index d378335d99..268cc68d60 100644
--- a/src/scalar_4x64_impl.h
+++ b/src/scalar_4x64_impl.h
@@ -7,6 +7,9 @@
 #ifndef SECP256K1_SCALAR_REPR_IMPL_H
 #define SECP256K1_SCALAR_REPR_IMPL_H
 
+#include "scalar.h"
+#include <string.h>
+
 /* Limbs of the secp256k1 order. */
 #define SECP256K1_N_0 ((uint64_t)0xBFD25E8CD0364141ULL)
 #define SECP256K1_N_1 ((uint64_t)0xBAAEDCE6AF48A03BULL)
@@ -946,4 +949,91 @@ SECP256K1_INLINE static void secp256k1_scalar_mul_shift_var(secp256k1_scalar *r,
     secp256k1_scalar_cadd_bit(r, 0, (l[(shift - 1) >> 6] >> ((shift - 1) & 0x3f)) & 1);
 }
 
+#define ROTL32(x,n) ((x) << (n) | (x) >> (32-(n)))
+#define QUARTERROUND(a,b,c,d) \
+  a += b; d = ROTL32(d ^ a, 16); \
+  c += d; b = ROTL32(b ^ c, 12); \
+  a += b; d = ROTL32(d ^ a, 8); \
+  c += d; b = ROTL32(b ^ c, 7);
+
+#ifdef WORDS_BIGENDIAN
+#define LE32(p) ((((p) & 0xFF) << 24) | (((p) & 0xFF00) << 8) | (((p) & 0xFF0000) >> 8) | (((p) & 0xFF000000) >> 24))
+#else
+#define LE32(p) (p)
+#endif
+
+static void secp256k1_scalar_chacha20(secp256k1_scalar *r1, secp256k1_scalar *r2, const unsigned char *seed, uint64_t idx) {
+    size_t n;
+    size_t over_count = 0;
+    uint32_t seed32[8];
+    uint32_t x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
+    int over1, over2;
+
+    memcpy((void *) seed32, (const void *) seed, 32);
+    do {
+        x0 = 0x61707865;
+        x1 = 0x3320646e;
+        x2 = 0x79622d32;
+        x3 = 0x6b206574;
+        x4 = LE32(seed32[0]);
+        x5 = LE32(seed32[1]);
+        x6 = LE32(seed32[2]);
+        x7 = LE32(seed32[3]);
+        x8 = LE32(seed32[4]);
+        x9 = LE32(seed32[5]);
+        x10 = LE32(seed32[6]);
+        x11 = LE32(seed32[7]);
+        x12 = idx;
+        x13 = idx >> 32;
+        x14 = 0;
+        x15 = over_count;
+
+        n = 10;
+        while (n--) {
+            QUARTERROUND(x0, x4, x8,x12)
+            QUARTERROUND(x1, x5, x9,x13)
+            QUARTERROUND(x2, x6,x10,x14)
+            QUARTERROUND(x3, x7,x11,x15)
+            QUARTERROUND(x0, x5,x10,x15)
+            QUARTERROUND(x1, x6,x11,x12)
+            QUARTERROUND(x2, x7, x8,x13)
+            QUARTERROUND(x3, x4, x9,x14)
+        }
+
+        x0 += 0x61707865;
+        x1 += 0x3320646e;
+        x2 += 0x79622d32;
+        x3 += 0x6b206574;
+        x4 += LE32(seed32[0]);
+        x5 += LE32(seed32[1]);
+        x6 += LE32(seed32[2]);
+        x7 += LE32(seed32[3]);
+        x8 += LE32(seed32[4]);
+        x9 += LE32(seed32[5]);
+        x10 += LE32(seed32[6]);
+        x11 += LE32(seed32[7]);
+        x12 += idx;
+        x13 += idx >> 32;
+        x14 += 0;
+        x15 += over_count;
+
+        r1->d[3] = (((uint64_t)  x0) << 32) | x1;
+        r1->d[2] = (((uint64_t)  x2) << 32) | x3;
+        r1->d[1] = (((uint64_t)  x4) << 32) | x5;
+        r1->d[0] = (((uint64_t)  x6) << 32) | x7;
+        r2->d[3] = (((uint64_t)  x8) << 32) | x9;
+        r2->d[2] = (((uint64_t) x10) << 32) | x11;
+        r2->d[1] = (((uint64_t) x12) << 32) | x13;
+        r2->d[0] = (((uint64_t) x14) << 32) | x15;
+
+        over1 = secp256k1_scalar_check_overflow(r1);
+        over2 = secp256k1_scalar_check_overflow(r2);
+        over_count++;
+   } while (over1 | over2);
+}
+
+#undef ROTL32
+#undef QUARTERROUND
+#undef LE32
+
 #endif /* SECP256K1_SCALAR_REPR_IMPL_H */
diff --git a/src/scalar_8x32_impl.h b/src/scalar_8x32_impl.h
index 4f9ed61fea..a9a934c43c 100644
--- a/src/scalar_8x32_impl.h
+++ b/src/scalar_8x32_impl.h
@@ -7,6 +7,8 @@
 #ifndef SECP256K1_SCALAR_REPR_IMPL_H
 #define SECP256K1_SCALAR_REPR_IMPL_H
 
+#include <string.h>
+
 /* Limbs of the secp256k1 order. */
 #define SECP256K1_N_0 ((uint32_t)0xD0364141UL)
 #define SECP256K1_N_1 ((uint32_t)0xBFD25E8CUL)
@@ -718,4 +720,99 @@ SECP256K1_INLINE static void secp256k1_scalar_mul_shift_var(secp256k1_scalar *r,
     secp256k1_scalar_cadd_bit(r, 0, (l[(shift - 1) >> 5] >> ((shift - 1) & 0x1f)) & 1);
 }
 
+#define ROTL32(x,n) ((x) << (n) | (x) >> (32-(n)))
+#define QUARTERROUND(a,b,c,d) \
+  a += b; d = ROTL32(d ^ a, 16); \
+  c += d; b = ROTL32(b ^ c, 12); \
+  a += b; d = ROTL32(d ^ a, 8); \
+  c += d; b = ROTL32(b ^ c, 7);
+
+#ifdef WORDS_BIGENDIAN
+#define LE32(p) ((((p) & 0xFF) << 24) | (((p) & 0xFF00) << 8) | (((p) & 0xFF0000) >> 8) | (((p) & 0xFF000000) >> 24))
+#else
+#define LE32(p) (p)
+#endif
+
+static void secp256k1_scalar_chacha20(secp256k1_scalar *r1, secp256k1_scalar *r2, const unsigned char *seed, uint64_t idx) {
+    size_t n;
+    size_t over_count = 0;
+    uint32_t seed32[8];
+    uint32_t x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
+    int over1, over2;
+
+    memcpy((void *) seed32, (const void *) seed, 32);
+    do {
+        x0 = 0x61707865;
+        x1 = 0x3320646e;
+        x2 = 0x79622d32;
+        x3 = 0x6b206574;
+        x4 = LE32(seed32[0]);
+        x5 = LE32(seed32[1]);
+        x6 = LE32(seed32[2]);
+        x7 = LE32(seed32[3]);
+        x8 = LE32(seed32[4]);
+        x9 = LE32(seed32[5]);
+        x10 = LE32(seed32[6]);
+        x11 = LE32(seed32[7]);
+        x12 = idx;
+        x13 = idx >> 32;
+        x14 = 0;
+        x15 = over_count;
+
+        n = 10;
+        while (n--) {
+            QUARTERROUND(x0, x4, x8,x12)
+            QUARTERROUND(x1, x5, x9,x13)
+            QUARTERROUND(x2, x6,x10,x14)
+            QUARTERROUND(x3, x7,x11,x15)
+            QUARTERROUND(x0, x5,x10,x15)
+            QUARTERROUND(x1, x6,x11,x12)
+            QUARTERROUND(x2, x7, x8,x13)
+            QUARTERROUND(x3, x4, x9,x14)
+        }
+
+        x0 += 0x61707865;
+        x1 += 0x3320646e;
+        x2 += 0x79622d32;
+        x3 += 0x6b206574;
+        x4 += LE32(seed32[0]);
+        x5 += LE32(seed32[1]);
+        x6 += LE32(seed32[2]);
+        x7 += LE32(seed32[3]);
+        x8 += LE32(seed32[4]);
+        x9 += LE32(seed32[5]);
+        x10 += LE32(seed32[6]);
+        x11 += LE32(seed32[7]);
+        x12 += idx;
+        x13 += idx >> 32;
+        x14 += 0;
+        x15 += over_count;
+
+        r1->d[7] = x0;
+        r1->d[6] = x1;
+        r1->d[5] = x2;
+        r1->d[4] = x3;
+        r1->d[3] = x4;
+        r1->d[2] = x5;
+        r1->d[1] = x6;
+        r1->d[0] = x7;
+        r2->d[7] = x8;
+        r2->d[6] = x9;
+        r2->d[5] = x10;
+        r2->d[4] = x11;
+        r2->d[3] = x12;
+        r2->d[2] = x13;
+        r2->d[1] = x14;
+        r2->d[0] = x15;
+
+        over1 = secp256k1_scalar_check_overflow(r1);
+        over2 = secp256k1_scalar_check_overflow(r2);
+        over_count++;
+   } while (over1 | over2);
+}
+
+#undef ROTL32
+#undef QUARTERROUND
+#undef LE32
+
 #endif /* SECP256K1_SCALAR_REPR_IMPL_H */
diff --git a/src/scalar_low_impl.h b/src/scalar_low_impl.h
index c80e70c5a2..88e52d8031 100644
--- a/src/scalar_low_impl.h
+++ b/src/scalar_low_impl.h
@@ -111,4 +111,9 @@ SECP256K1_INLINE static int secp256k1_scalar_eq(const secp256k1_scalar *a, const
     return *a == *b;
 }
 
+SECP256K1_INLINE static void secp256k1_scalar_chacha20(secp256k1_scalar *r1, secp256k1_scalar *r2, const unsigned char *seed, uint64_t n) {
+    *r1 = (seed[0] + n) % EXHAUSTIVE_TEST_ORDER;
+    *r2 = (seed[1] + n) % EXHAUSTIVE_TEST_ORDER;
+}
+
 #endif /* SECP256K1_SCALAR_REPR_IMPL_H */
diff --git a/src/secp256k1.c b/src/secp256k1.c
index a3f446e507..81d3de5e23 100644
--- a/src/secp256k1.c
+++ b/src/secp256k1.c
@@ -413,6 +413,54 @@ static SECP256K1_INLINE void buffer_append(unsigned char *buf, unsigned int *off
     *offset += len;
 }
 
+/* Initializes SHA256 with fixed midstate. This midstate was computed by applying
+ * SHA256 to SHA256("BIPSchnorrDerive")||SHA256("BIPSchnorrDerive"). */
+static void secp256k1_nonce_function_bipschnorr_sha256_tagged(secp256k1_sha256 *sha) {
+    secp256k1_sha256_initialize(sha);
+    sha->s[0] = 0x1cd78ec3ul;
+    sha->s[1] = 0xc4425f87ul;
+    sha->s[2] = 0xb4f1a9f1ul;
+    sha->s[3] = 0xa16abd8dul;
+    sha->s[4] = 0x5a6dea72ul;
+    sha->s[5] = 0xd28469e3ul;
+    sha->s[6] = 0x17119b2eul;
+    sha->s[7] = 0x7bd19a16ul;
+    sha->bytes = 64;
+}
+
+/* This nonce function is described in BIP-schnorr
+ * (https://github.com/sipa/bips/blob/bip-schnorr/bip-schnorr.mediawiki) */
+static int nonce_function_bipschnorr(unsigned char *nonce32, const unsigned char *msg32, const unsigned char *key32, const unsigned char *algo16, void *data, unsigned int counter) {
+    secp256k1_sha256 sha;
+
+    if (counter != 0) {
+        return 0;
+    }
+    /* Tag the hash with algo16 which is important to avoid nonce reuse across
+     * algorithms. If the this nonce function is used in BIP-schnorr signing as
+     * defined in the spec, an optimized tagging implementation is used. */
+    if (algo16 != NULL) {
+        if (memcmp(algo16, "BIPSchnorrDerive", 16) == 0) {
+            secp256k1_nonce_function_bipschnorr_sha256_tagged(&sha);
+        } else {
+            secp256k1_sha256_initialize_tagged(&sha, algo16, 16);
+        }
+    } else {
+        /* If algo16 is NULL use a 14-bytes tag to rule out collisions with any
+         * non-NULL algo16 */
+        secp256k1_sha256_initialize_tagged(&sha, (unsigned char *) "BIPSchnorrNULL", 14);
+    }
+
+    /* Hash x||msg using the tagged hash as per the spec */
+    secp256k1_sha256_write(&sha, key32, 32);
+    secp256k1_sha256_write(&sha, msg32, 32);
+    if (data != NULL) {
+        secp256k1_sha256_write(&sha, data, 32);
+    }
+    secp256k1_sha256_finalize(&sha, nonce32);
+    return 1;
+}
+
 static int nonce_function_rfc6979(unsigned char *nonce32, const unsigned char *msg32, const unsigned char *key32, const unsigned char *algo16, void *data, unsigned int counter) {
    unsigned char keydata[112];
    unsigned int offset = 0;
@@ -443,6 +491,7 @@ static int nonce_function_rfc6979(unsigned char *nonce32, const unsigned char *m
    return 1;
 }
 
+const secp256k1_nonce_function secp256k1_nonce_function_bipschnorr = nonce_function_bipschnorr;
 const secp256k1_nonce_function secp256k1_nonce_function_rfc6979 = nonce_function_rfc6979;
 const secp256k1_nonce_function secp256k1_nonce_function_default = nonce_function_rfc6979;
 
@@ -681,10 +730,139 @@ int secp256k1_ec_pubkey_combine(const secp256k1_context* ctx, secp256k1_pubkey *
     return 1;
 }
 
+/* Converts the point encoded by a secp256k1_pubkey into its absolute value,
+ * i.e. keeps it as is if it is positive and otherwise negates it. Sign is set
+ * to 1 if the input point was negative and set to 0 otherwise. */
+static void secp256k1_ec_pubkey_absolute(const secp256k1_context* ctx, secp256k1_pubkey *pubkey, int *sign) {
+   secp256k1_ge ge;
+    secp256k1_pubkey_load(ctx, &ge, pubkey);
+    if (sign != NULL) {
+        *sign = 0;
+    }
+    if (!secp256k1_fe_is_quad_var(&ge.y)) {
+        secp256k1_ge_neg(&ge, &ge);
+        if (sign != NULL) {
+            *sign = 1;
+        }
+    }
+    secp256k1_pubkey_save(pubkey, &ge);
+}
+
+int secp256k1_xonly_pubkey_create(const secp256k1_context* ctx, secp256k1_xonly_pubkey *pubkey, const unsigned char *seckey) {
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
+    ARG_CHECK(pubkey != NULL);
+    ARG_CHECK(seckey != NULL);
+
+    if (!secp256k1_ec_pubkey_create(ctx, (secp256k1_pubkey *) pubkey, seckey)) {
+        return 0;
+    }
+    secp256k1_ec_pubkey_absolute(ctx, (secp256k1_pubkey *) pubkey, NULL);
+    return 1;
+}
+
+int secp256k1_xonly_pubkey_parse(const secp256k1_context* ctx, secp256k1_xonly_pubkey* pubkey, const unsigned char *input32) {
+    /* TODO parse directly from 32 byte buffer */
+    unsigned char buf[33];
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(pubkey != NULL);
+    ARG_CHECK(input32 != NULL);
+
+    buf[0] = SECP256K1_TAG_PUBKEY_EVEN;
+    memcpy(&buf[1], input32, 32);
+    if (!secp256k1_ec_pubkey_parse(ctx, (secp256k1_pubkey *) pubkey, buf, sizeof(buf))) {
+        return 0;
+    }
+    secp256k1_ec_pubkey_absolute(ctx, (secp256k1_pubkey *) pubkey, NULL);
+    return 1;
+}
+
+int secp256k1_xonly_pubkey_serialize(const secp256k1_context* ctx, unsigned char *output32, const secp256k1_xonly_pubkey* pubkey) {
+    /* TODO serialize directly into 32 byte buffer */
+    unsigned char buf[33];
+    size_t outputlen = sizeof(buf);
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(pubkey != NULL);
+    ARG_CHECK(output32 != NULL);
+
+    if (!secp256k1_ec_pubkey_serialize(ctx, buf, &outputlen, (const secp256k1_pubkey *) pubkey, SECP256K1_EC_COMPRESSED)) {
+        return 0;
+    }
+    memcpy(output32, &buf[1], 32);
+    return 1;
+}
+
+int secp256k1_xonly_pubkey_from_pubkey(const secp256k1_context* ctx, secp256k1_xonly_pubkey *xonly_pubkey, int *sign, const secp256k1_pubkey *pubkey) {
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(xonly_pubkey != NULL);
+    ARG_CHECK(pubkey != NULL);
+
+    *xonly_pubkey = *(const secp256k1_xonly_pubkey *) pubkey;
+
+    secp256k1_ec_pubkey_absolute(ctx, (secp256k1_pubkey *) xonly_pubkey, sign);
+    return 1;
+}
+
+int secp256k1_xonly_privkey_tweak_add(const secp256k1_context* ctx, unsigned char *seckey32, const unsigned char *tweak32) {
+    secp256k1_ge ge;
+    secp256k1_pubkey pubkey;
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
+    ARG_CHECK(seckey32 != NULL);
+    ARG_CHECK(tweak32 != NULL);
+
+    if (!secp256k1_ec_pubkey_create(ctx, &pubkey, seckey32)) {
+        return 0;
+    }
+    secp256k1_pubkey_load(ctx, &ge, &pubkey);
+    if (!secp256k1_fe_is_quad_var(&ge.y)) {
+        if (!secp256k1_ec_privkey_negate(ctx, seckey32)) {
+            return 0;
+        }
+    }
+
+    return secp256k1_ec_privkey_tweak_add(ctx, seckey32, tweak32);
+}
+
+int secp256k1_xonly_pubkey_tweak_add(const secp256k1_context* ctx, secp256k1_xonly_pubkey *output_pubkey, int *is_positive, const secp256k1_xonly_pubkey *internal_pubkey, const unsigned char *tweak32) {
+    secp256k1_pubkey pubkey_tmp;
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(output_pubkey != NULL);
+    ARG_CHECK(is_positive != NULL);
+    ARG_CHECK(internal_pubkey != NULL);
+    ARG_CHECK(tweak32 != NULL);
+
+    pubkey_tmp = *(secp256k1_pubkey *)internal_pubkey;
+    if(!secp256k1_ec_pubkey_tweak_add(ctx, &pubkey_tmp, tweak32)) {
+        return 0;
+    }
+    return secp256k1_xonly_pubkey_from_pubkey(ctx, output_pubkey, is_positive, &pubkey_tmp);
+}
+
+int secp256k1_xonly_pubkey_tweak_verify(const secp256k1_context* ctx, const secp256k1_xonly_pubkey *output_pubkey, int is_positive, const secp256k1_xonly_pubkey *internal_pubkey, const unsigned char *tweak32) {
+    secp256k1_xonly_pubkey pk_expected;
+    int is_positive_expected;
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
+    ARG_CHECK(internal_pubkey != NULL);
+    ARG_CHECK(output_pubkey != NULL);
+    ARG_CHECK(tweak32 != NULL);
+
+    if (!secp256k1_xonly_pubkey_tweak_add(ctx, &pk_expected, &is_positive_expected, internal_pubkey, tweak32)) {
+        return 0;
+    }
+    return memcmp(&pk_expected, output_pubkey, sizeof(pk_expected)) == 0
+            && is_positive_expected == is_positive;
+}
+
 #ifdef ENABLE_MODULE_ECDH
 # include "modules/ecdh/main_impl.h"
 #endif
 
+#ifdef ENABLE_MODULE_SCHNORRSIG
+# include "modules/schnorrsig/main_impl.h"
+#endif
+
 #ifdef ENABLE_MODULE_RECOVERY
 # include "modules/recovery/main_impl.h"
 #endif
diff --git a/src/tests.c b/src/tests.c
index d408a5c30a..3a23857631 100644
--- a/src/tests.c
+++ b/src/tests.c
@@ -443,6 +443,60 @@ void run_sha256_tests(void) {
     }
 }
 
+/* Tests for the equality of two sha256 structs. This function only produces a
+ * correct result if an integer multiple of 64 many bytes have been written
+ * into the hash functions. */
+void test_sha256_eq(secp256k1_sha256 *sha1, secp256k1_sha256 *sha2) {
+    unsigned char buf[32] = { 0 };
+    unsigned char buf2[32];
+
+    /* Is buffer fully consumed? */
+    CHECK((sha1->bytes & 0x3F) == 0);
+
+    /* Compare the struct excluding the the buffer, because it may be
+     * uninitialized or already included in the state. */
+    CHECK(sha1->bytes == sha2->bytes);
+    CHECK(memcmp(sha1->s, sha2->s, sizeof(sha1->s)) == 0);
+
+    /* Compare the output */
+    secp256k1_sha256_write(sha1, buf, 32);
+    secp256k1_sha256_write(sha2, buf, 32);
+    secp256k1_sha256_finalize(sha1, buf);
+    secp256k1_sha256_finalize(sha2, buf2);
+    CHECK(memcmp(buf, buf2, 32) == 0);
+}
+
+void run_nonce_function_bipschnorr_tests(void) {
+    char tag[16] = "BIPSchnorrDerive";
+    secp256k1_sha256 sha;
+    secp256k1_sha256 sha_optimized;
+    unsigned char nonces[3][32];
+    unsigned char msg[32];
+    unsigned char key[32];
+
+    /* Check that hash initialized by
+     * secp256k1_nonce_function_bipschnorr_sha256_tagged has the expected
+     * state. */
+    secp256k1_sha256_initialize_tagged(&sha, (unsigned char *) tag, sizeof(tag));
+    secp256k1_nonce_function_bipschnorr_sha256_tagged(&sha_optimized);
+    test_sha256_eq(&sha, &sha_optimized);
+
+    /* Check that different choices of the algo16 argument result in different
+     * hashes. */
+    memset(msg, 0, sizeof(msg));
+    memset(key, 1, sizeof(key));
+    CHECK(nonce_function_bipschnorr(nonces[0], msg, key, (unsigned char *) "BIPSchnorrDerive", NULL, 0));
+    CHECK(nonce_function_bipschnorr(nonces[1], msg, key, NULL, NULL, 0));
+    CHECK(memcmp(nonces[1], nonces[0], sizeof(nonces[1])) != 0);
+    CHECK(nonce_function_bipschnorr(nonces[2], msg, key, (unsigned char *) "something16chars", NULL, 0));
+    CHECK(memcmp(nonces[2], nonces[0], sizeof(nonces[2])) != 0);
+    CHECK(memcmp(nonces[2], nonces[1], sizeof(nonces[2])) != 0);
+
+    /* Check that counter != 0 makes nonce function fail. */
+    CHECK(nonce_function_bipschnorr(nonces[0], msg, key, NULL, NULL, 0) == 1);
+    CHECK(nonce_function_bipschnorr(nonces[0], msg, key, NULL, NULL, 1) == 0);
+}
+
 void run_hmac_sha256_tests(void) {
     static const char *keys[6] = {
         "\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b",
@@ -1077,12 +1131,122 @@ void scalar_test(void) {
 
 }
 
+void scalar_chacha_tests(void) {
+    /* Test vectors 1 to 4 from https://tools.ietf.org/html/rfc8439#appendix-A
+     * Note that scalar_set_b32 and scalar_get_b32 represent integers
+     * underlying the scalar in big-endian format. */
+    unsigned char expected1[64] = {
+        0xad, 0xe0, 0xb8, 0x76, 0x90, 0x3d, 0xf1, 0xa0,
+        0xe5, 0x6a, 0x5d, 0x40, 0x28, 0xbd, 0x86, 0x53,
+        0xb8, 0x19, 0xd2, 0xbd, 0x1a, 0xed, 0x8d, 0xa0,
+        0xcc, 0xef, 0x36, 0xa8, 0xc7, 0x0d, 0x77, 0x8b,
+        0x7c, 0x59, 0x41, 0xda, 0x8d, 0x48, 0x57, 0x51,
+        0x3f, 0xe0, 0x24, 0x77, 0x37, 0x4a, 0xd8, 0xb8,
+        0xf4, 0xb8, 0x43, 0x6a, 0x1c, 0xa1, 0x18, 0x15,
+        0x69, 0xb6, 0x87, 0xc3, 0x86, 0x65, 0xee, 0xb2
+    };
+    unsigned char expected2[64] = {
+        0xbe, 0xe7, 0x07, 0x9f, 0x7a, 0x38, 0x51, 0x55,
+        0x7c, 0x97, 0xba, 0x98, 0x0d, 0x08, 0x2d, 0x73,
+        0xa0, 0x29, 0x0f, 0xcb, 0x69, 0x65, 0xe3, 0x48,
+        0x3e, 0x53, 0xc6, 0x12, 0xed, 0x7a, 0xee, 0x32,
+        0x76, 0x21, 0xb7, 0x29, 0x43, 0x4e, 0xe6, 0x9c,
+        0xb0, 0x33, 0x71, 0xd5, 0xd5, 0x39, 0xd8, 0x74,
+        0x28, 0x1f, 0xed, 0x31, 0x45, 0xfb, 0x0a, 0x51,
+        0x1f, 0x0a, 0xe1, 0xac, 0x6f, 0x4d, 0x79, 0x4b
+    };
+    unsigned char seed3[32] = {
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01
+    };
+    unsigned char expected3[64] = {
+        0x24, 0x52, 0xeb, 0x3a, 0x92, 0x49, 0xf8, 0xec,
+        0x8d, 0x82, 0x9d, 0x9b, 0xdd, 0xd4, 0xce, 0xb1,
+        0xe8, 0x25, 0x20, 0x83, 0x60, 0x81, 0x8b, 0x01,
+        0xf3, 0x84, 0x22, 0xb8, 0x5a, 0xaa, 0x49, 0xc9,
+        0xbb, 0x00, 0xca, 0x8e, 0xda, 0x3b, 0xa7, 0xb4,
+        0xc4, 0xb5, 0x92, 0xd1, 0xfd, 0xf2, 0x73, 0x2f,
+        0x44, 0x36, 0x27, 0x4e, 0x25, 0x61, 0xb3, 0xc8,
+        0xeb, 0xdd, 0x4a, 0xa6, 0xa0, 0x13, 0x6c, 0x00
+    };
+    unsigned char seed4[32] = {
+        0x00, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+    };
+    unsigned char expected4[64] = {
+        0xfb, 0x4d, 0xd5, 0x72, 0x4b, 0xc4, 0x2e, 0xf1,
+        0xdf, 0x92, 0x26, 0x36, 0x32, 0x7f, 0x13, 0x94,
+        0xa7, 0x8d, 0xea, 0x8f, 0x5e, 0x26, 0x90, 0x39,
+        0xa1, 0xbe, 0xbb, 0xc1, 0xca, 0xf0, 0x9a, 0xae,
+        0xa2, 0x5a, 0xb2, 0x13, 0x48, 0xa6, 0xb4, 0x6c,
+        0x1b, 0x9d, 0x9b, 0xcb, 0x09, 0x2c, 0x5b, 0xe6,
+        0x54, 0x6c, 0xa6, 0x24, 0x1b, 0xec, 0x45, 0xd5,
+        0x87, 0xf4, 0x74, 0x73, 0x96, 0xf0, 0x99, 0x2e
+    };
+    unsigned char seed5[32] = {
+        0x32, 0x56, 0x56, 0xf4, 0x29, 0x02, 0xc2, 0xf8,
+        0xa3, 0x4b, 0x96, 0xf5, 0xa7, 0xf7, 0xe3, 0x6c,
+        0x92, 0xad, 0xa5, 0x18, 0x1c, 0xe3, 0x41, 0xae,
+        0xc3, 0xf3, 0x18, 0xd0, 0xfa, 0x5b, 0x72, 0x53
+    };
+    unsigned char expected5[64] = {
+        0xe7, 0x56, 0xd3, 0x28, 0xe9, 0xc6, 0x19, 0x5c,
+        0x6f, 0x17, 0x8e, 0x21, 0x8c, 0x1e, 0x72, 0x11,
+        0xe7, 0xbd, 0x17, 0x0d, 0xac, 0x14, 0xad, 0xe9,
+        0x3d, 0x9f, 0xb6, 0x92, 0xd6, 0x09, 0x20, 0xfb,
+        0x43, 0x8e, 0x3b, 0x6d, 0xe3, 0x33, 0xdc, 0xc7,
+        0x6c, 0x07, 0x6f, 0xbb, 0x1f, 0xb4, 0xc8, 0xb5,
+        0xe3, 0x6c, 0xe5, 0x12, 0xd9, 0xd7, 0x64, 0x0c,
+        0xf5, 0xa7, 0x0d, 0xab, 0x79, 0x03, 0xf1, 0x81
+    };
+
+    secp256k1_scalar exp_r1, exp_r2;
+    secp256k1_scalar r1, r2;
+    unsigned char seed0[32] = { 0 };
+
+    secp256k1_scalar_chacha20(&r1, &r2, seed0, 0);
+    secp256k1_scalar_set_b32(&exp_r1, &expected1[0], NULL);
+    secp256k1_scalar_set_b32(&exp_r2, &expected1[32], NULL);
+    CHECK(secp256k1_scalar_eq(&exp_r1, &r1));
+    CHECK(secp256k1_scalar_eq(&exp_r2, &r2));
+
+    secp256k1_scalar_chacha20(&r1, &r2, seed0, 1);
+    secp256k1_scalar_set_b32(&exp_r1, &expected2[0], NULL);
+    secp256k1_scalar_set_b32(&exp_r2, &expected2[32], NULL);
+    CHECK(secp256k1_scalar_eq(&exp_r1, &r1));
+    CHECK(secp256k1_scalar_eq(&exp_r2, &r2));
+
+    secp256k1_scalar_chacha20(&r1, &r2, seed3, 1);
+    secp256k1_scalar_set_b32(&exp_r1, &expected3[0], NULL);
+    secp256k1_scalar_set_b32(&exp_r2, &expected3[32], NULL);
+    CHECK(secp256k1_scalar_eq(&exp_r1, &r1));
+    CHECK(secp256k1_scalar_eq(&exp_r2, &r2));
+
+    secp256k1_scalar_chacha20(&r1, &r2, seed4, 2);
+    secp256k1_scalar_set_b32(&exp_r1, &expected4[0], NULL);
+    secp256k1_scalar_set_b32(&exp_r2, &expected4[32], NULL);
+    CHECK(secp256k1_scalar_eq(&exp_r1, &r1));
+    CHECK(secp256k1_scalar_eq(&exp_r2, &r2));
+
+    secp256k1_scalar_chacha20(&r1, &r2, seed5, 0x6ff8602a7a78e2f2ULL);
+    secp256k1_scalar_set_b32(&exp_r1, &expected5[0], NULL);
+    secp256k1_scalar_set_b32(&exp_r2, &expected5[32], NULL);
+    CHECK(secp256k1_scalar_eq(&exp_r1, &r1));
+    CHECK(secp256k1_scalar_eq(&exp_r2, &r2));
+}
+
 void run_scalar_tests(void) {
     int i;
     for (i = 0; i < 128 * count; i++) {
         scalar_test();
     }
 
+    scalar_chacha_tests();
+
     {
         /* (-1)+1 should be zero. */
         secp256k1_scalar s, o;
@@ -4104,6 +4268,222 @@ void run_eckey_edge_case_test(void) {
     secp256k1_context_set_illegal_callback(ctx, NULL, NULL);
 }
 
+void test_xonly_pubkey(void) {
+    unsigned char sk[32] = { 0 };
+    unsigned char ones32[32];
+    unsigned char zeros64[64] = { 0 };
+    secp256k1_pubkey xy_pk;
+    secp256k1_xonly_pubkey xonly_pk;
+    secp256k1_xonly_pubkey xonly_pk_tmp;
+    secp256k1_ge pk1;
+    secp256k1_ge pk2;
+    secp256k1_fe y;
+    int is_positive;
+    unsigned char buf32[32];
+
+    /* sk = 0 should fail */
+    CHECK(secp256k1_xonly_pubkey_create(ctx, &xonly_pk, sk) == 0);
+
+    /* Check that X coordinate of normal pubkey and x-only pubkey matches
+     * and that due to choice of secret key the Y coordinates are each others
+     * additive inverse. */
+    sk[0] = 6;
+    CHECK(secp256k1_ec_pubkey_create(ctx, &xy_pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_create(ctx, &xonly_pk, sk) == 1);
+    secp256k1_pubkey_load(ctx, &pk1, &xy_pk);
+    secp256k1_pubkey_load(ctx, &pk2, (secp256k1_pubkey *) &xonly_pk);
+    CHECK(secp256k1_fe_equal(&pk1.x, &pk2.x) == 1);
+    secp256k1_fe_negate(&y, &pk2.y, 1);
+    CHECK(secp256k1_fe_equal(&pk1.y, &y) == 1);
+
+    /* Test from_pubkey */
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &xonly_pk_tmp, &is_positive, &xy_pk) == 1);
+    CHECK(memcmp(&xonly_pk_tmp, &xonly_pk, sizeof(xonly_pk)) == 0);
+    CHECK(is_positive == 1);
+
+    /* Serialization and parse roundtrip */
+    CHECK(secp256k1_xonly_pubkey_create(ctx, &xonly_pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_serialize(ctx, buf32, &xonly_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_parse(ctx, &xonly_pk_tmp, buf32) == 1);
+    CHECK(memcmp(&xonly_pk, &xonly_pk_tmp, sizeof(xonly_pk)) == 0);
+
+    /* Can't parse a byte string that's not a valid X coordinate */
+    memset(ones32, 0xFF, sizeof(ones32));
+    CHECK(secp256k1_xonly_pubkey_parse(ctx, &xonly_pk_tmp, ones32) == 0);
+    CHECK(memcmp(&xonly_pk_tmp, zeros64, sizeof(xonly_pk_tmp)) == 0);
+}
+
+void test_xonly_pubkey_api(void) {
+    secp256k1_xonly_pubkey pk;
+    secp256k1_xonly_pubkey pk_tweaked;
+    secp256k1_pubkey xy_pk;
+    unsigned char sk[32];
+    unsigned char buf32[32];
+    unsigned char tweak[32];
+    int pk_is_positive;
+
+    /** setup **/
+    secp256k1_context *none = secp256k1_context_create(SECP256K1_CONTEXT_NONE);
+    secp256k1_context *sign = secp256k1_context_create(SECP256K1_CONTEXT_SIGN);
+    secp256k1_context *vrfy = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY);
+    int ecount;
+
+    secp256k1_context_set_error_callback(none, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_error_callback(sign, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_error_callback(vrfy, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_illegal_callback(none, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_illegal_callback(sign, counting_illegal_callback_fn, &ecount);
+    secp256k1_context_set_illegal_callback(vrfy, counting_illegal_callback_fn, &ecount);
+
+    secp256k1_rand256(sk);
+    secp256k1_rand256(tweak);
+
+    ecount = 0;
+    CHECK(secp256k1_xonly_pubkey_create(none, &pk, sk) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_xonly_pubkey_create(sign, &pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_create(vrfy, &pk, sk) == 0);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_xonly_pubkey_create(sign, NULL, sk) == 0);
+    CHECK(ecount == 3);
+    CHECK(secp256k1_xonly_pubkey_create(sign, &pk, NULL) == 0);
+    CHECK(ecount == 4);
+
+    ecount = 0;
+    CHECK(secp256k1_xonly_pubkey_create(sign, &pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_serialize(none, buf32, &pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_serialize(none, NULL, &pk) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_xonly_pubkey_serialize(none, buf32, NULL) == 0);
+    CHECK(ecount == 2);
+
+    ecount = 0;
+    CHECK(secp256k1_xonly_pubkey_parse(none, &pk, buf32) == 1);
+    CHECK(secp256k1_xonly_pubkey_parse(none, NULL, buf32) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_xonly_pubkey_parse(none, &pk, NULL) == 0);
+    CHECK(ecount == 2);
+
+    ecount = 0;
+    CHECK(secp256k1_xonly_privkey_tweak_add(none, sk, tweak) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_xonly_privkey_tweak_add(sign, sk, tweak) == 1);
+    CHECK(secp256k1_xonly_privkey_tweak_add(vrfy, sk, tweak) == 0);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_xonly_privkey_tweak_add(sign, NULL, tweak) == 0);
+    CHECK(ecount == 3);
+    CHECK(secp256k1_xonly_privkey_tweak_add(sign, sk, NULL) == 0);
+    CHECK(ecount == 4);
+
+    ecount = 0;
+    CHECK(secp256k1_xonly_pubkey_tweak_add(none, &pk, &pk_is_positive, &pk, tweak) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(sign, &pk, &pk_is_positive, &pk, tweak) == 0);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(vrfy, &pk, &pk_is_positive, &pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(vrfy, NULL, &pk_is_positive, &pk, tweak) == 0);
+    CHECK(ecount == 3);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(vrfy, &pk, NULL, &pk, tweak) == 0);
+    CHECK(ecount == 4);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(vrfy, &pk, &pk_is_positive, NULL, tweak) == 0);
+    CHECK(ecount == 5);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(vrfy, &pk, &pk_is_positive, &pk, NULL) == 0);
+    CHECK(ecount == 6);
+
+    ecount = 0;
+    CHECK(secp256k1_xonly_pubkey_tweak_add(vrfy, &pk_tweaked, &pk_is_positive, &pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_verify(none, &pk_tweaked, pk_is_positive, &pk, tweak) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_verify(sign, &pk_tweaked, pk_is_positive, &pk, tweak) == 0);
+    CHECK(ecount == 2);
+    CHECK(secp256k1_xonly_pubkey_tweak_verify(vrfy, &pk_tweaked, pk_is_positive, &pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_verify(vrfy, NULL, pk_is_positive, &pk, tweak) == 0);
+    CHECK(ecount == 3);
+    /* invalid is_positive value */
+    CHECK(secp256k1_xonly_pubkey_tweak_verify(vrfy, &pk_tweaked, 2, &pk, tweak) == 0);
+    CHECK(ecount == 3);
+    CHECK(secp256k1_xonly_pubkey_tweak_verify(vrfy, &pk_tweaked, pk_is_positive, NULL, tweak) == 0);
+    CHECK(ecount == 4);
+    CHECK(secp256k1_xonly_pubkey_tweak_verify(vrfy, &pk_tweaked, pk_is_positive, &pk, NULL) == 0);
+    CHECK(ecount == 5);
+
+
+    ecount = 0;
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(none, &pk, &pk_is_positive, &xy_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(sign, &pk, &pk_is_positive, &xy_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(vrfy, &pk, &pk_is_positive, &xy_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(none, NULL, &pk_is_positive, &xy_pk) == 0);
+    CHECK(ecount == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(none, &pk, NULL, &xy_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(none, &pk, &pk_is_positive, NULL) == 0);
+    CHECK(ecount == 2);
+
+    secp256k1_context_destroy(none);
+    secp256k1_context_destroy(sign);
+    secp256k1_context_destroy(vrfy);
+}
+
+void test_xonly_pubkey_tweak(void) {
+    unsigned char zeros[32];
+    unsigned char overflows[32];
+    unsigned char sk[32];
+    secp256k1_xonly_pubkey internal_pk;
+    secp256k1_xonly_pubkey output_pk;
+    secp256k1_pubkey xy_pk;
+    int is_positive;
+    unsigned char tweak[32];
+
+    memset(zeros, 0, sizeof(zeros));
+    memset(overflows, 0xff, sizeof(zeros));
+    secp256k1_rand256(sk);
+    CHECK(secp256k1_xonly_pubkey_create(ctx, &internal_pk, sk) == 1);
+
+    memset(tweak, 1, sizeof(tweak));
+    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &is_positive, &internal_pk, tweak) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_verify(ctx, &output_pk, is_positive, &internal_pk, tweak) == 1);
+    /* Using privkey_tweak_add gives the same result */
+    CHECK(secp256k1_xonly_privkey_tweak_add(ctx, sk, tweak) == 1);
+    CHECK(secp256k1_ec_pubkey_create(ctx, &xy_pk, sk) == 1);
+    CHECK(secp256k1_xonly_pubkey_from_pubkey(ctx, &output_pk, &is_positive, &xy_pk) == 1);
+    CHECK(secp256k1_xonly_pubkey_tweak_verify(ctx, &output_pk, is_positive, &internal_pk, tweak) == 1);
+
+    /* Wrong is_positive */
+    CHECK(secp256k1_xonly_pubkey_tweak_verify(ctx, &output_pk, !is_positive, &internal_pk, tweak) == 0);
+    /* Wrong public key */
+    CHECK(secp256k1_xonly_pubkey_tweak_verify(ctx, &internal_pk, is_positive, &internal_pk, tweak) == 0);
+
+    /* Overflowing tweak not allowed */
+    CHECK(secp256k1_xonly_pubkey_tweak_verify(ctx, &output_pk, is_positive, &internal_pk, overflows) == 0);
+    CHECK(secp256k1_xonly_privkey_tweak_add(ctx, sk, overflows) == 0);
+    CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &output_pk, &is_positive, &internal_pk, overflows) == 0);
+}
+
+/* Starts with an initial pubkey and recursively creates N_PUBKEYS - 1
+ * additional pubkeys by calling tweak_add. Then verifies every tweak starting
+ * from the last pubkey. */
+#define N_PUBKEYS 32
+void test_xonly_pubkey_tweak_recursive(void) {
+    unsigned char sk[32];
+    secp256k1_xonly_pubkey pk[N_PUBKEYS];
+    int is_positive[N_PUBKEYS];
+    unsigned char tweak[N_PUBKEYS - 1][32];
+    int i;
+
+    secp256k1_rand256(sk);
+    CHECK(secp256k1_xonly_pubkey_create(ctx, &pk[0], sk) == 1);
+    /* Add tweaks */
+    for (i = 0; i < N_PUBKEYS - 1; i++) {
+        memset(tweak[i], i + 1, sizeof(tweak[i]));
+        CHECK(secp256k1_xonly_pubkey_tweak_add(ctx, &pk[i + 1], &is_positive[i +  1], &pk[i], tweak[i]) == 1);
+    }
+
+    /* Verify tweaks */
+    for (i = N_PUBKEYS - 1; i > 0; i--) {
+        CHECK(secp256k1_xonly_pubkey_tweak_verify(ctx, &pk[i], is_positive[i], &pk[i - 1], tweak[i - 1]) == 1);
+    }
+}
+#undef N_PUBKEYS
+
 void random_sign(secp256k1_scalar *sigr, secp256k1_scalar *sigs, const secp256k1_scalar *key, const secp256k1_scalar *msg, int *recid) {
     secp256k1_scalar nonce;
     do {
@@ -5162,6 +5542,10 @@ void run_ecdsa_openssl(void) {
 # include "modules/ecdh/tests_impl.h"
 #endif
 
+#ifdef ENABLE_MODULE_SCHNORRSIG
+# include "modules/schnorrsig/tests_impl.h"
+#endif
+
 #ifdef ENABLE_MODULE_RECOVERY
 # include "modules/recovery/tests_impl.h"
 #endif
@@ -5208,6 +5592,7 @@ int main(int argc, char **argv) {
     }
     secp256k1_rand_seed(seed16);
 
+    setbuf(stdout, NULL);
     printf("test count = %i\n", count);
     printf("random seed = %02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x\n", seed16[0], seed16[1], seed16[2], seed16[3], seed16[4], seed16[5], seed16[6], seed16[7], seed16[8], seed16[9], seed16[10], seed16[11], seed16[12], seed16[13], seed16[14], seed16[15]);
 
@@ -5270,11 +5655,23 @@ int main(int argc, char **argv) {
     /* EC key edge cases */
     run_eckey_edge_case_test();
 
+    /* xonly key test cases */
+    test_xonly_pubkey();
+    test_xonly_pubkey_api();
+    test_xonly_pubkey_tweak();
+    test_xonly_pubkey_tweak_recursive();
+
 #ifdef ENABLE_MODULE_ECDH
     /* ecdh tests */
     run_ecdh_tests();
 #endif
 
+    run_nonce_function_bipschnorr_tests();
+#ifdef ENABLE_MODULE_SCHNORRSIG
+    /* Schnorrsig tests */
+    run_schnorrsig_tests();
+#endif
+
     /* ecdsa tests */
     run_random_pubkeys();
     run_ecdsa_der_parse();