feat(crypto): support OpenSSL 1.1.x with per-version backend files by walterchris · Pull Request #500 · Azure/azihsm-sdk

walterchris · 2026-06-30T06:44:44Z

Problem

azihsm_crypto is OpenSSL-3.x-only — it uses EVP_MAC, OSSL_PARAM, library
contexts, and provider fetch. That blocks the OpenSSL 1.1.x engine, which
depends on the crate transitively via azihsm_api. The engine targets the
legacy 1.1 ABI; the provider serves 3.x.

Change

Add a 1.1.x backend for each algorithm alongside the existing 3.x one,
selected at build time:

build.rs emits cfg(ossl300) from the OpenSSL version openssl-sys
exposes (DEP_OPENSSL_VERSION_NUMBER).
Each algorithm gains a *_ossl11.rs compiled under cfg(not(ossl300)).
The existing *_ossl.rs stays unchanged as the cfg(ossl300) backend
(no rename, no diff).
libctx.rs (private OSSL_LIB_CTX isolation) is gated to 3.x; 1.1 has no
library contexts or providers.

Covers aes (cbc/ecb/gcm/xts), ecc/ecdh, hash, hmac, kdf/hkdf, and rsa
(enc/sign/hash-sign). The version-agnostic code (key, kbkdf, hpke,
aead_envelope, der, x509, secret) is unchanged.

The 1.1.x backends match the implementation used before the crate's 3.x-only
rewrite (commit 8277a01e).

1.1 correctness notes

Two behaviors where 1.1 is stricter than 3.x, handled in the 1.1 backends:

AES-ECB: set_padding(false) is called after EVP_*Init (which resets
padding to on). On 1.1 a pre-init call is silently dropped, which would add a
spurious padding block to block-aligned input — this also covers AES-KW/KWP
and RSA-AES-KW, which build on ECB.
HKDF: zero-length output (invalid per RFC 5869) and a mismatched
Extract-mode length are rejected, matching the 3.x / CNG backends; the 1.1
EVP_PKEY HKDF path otherwise accepts both silently.

Validation

3.x: build, clippy -D warnings, 477 tests — all pass, unchanged.
1.1.x (OpenSSL 1.1.1w): 477/477 tests pass, clippy clean.
Engine matrix (Ubuntu 20.04 / OpenSSL 1.1.1f): the cdylib builds with
--features engine, passes clippy -D warnings, loads via
openssl engine -t → [ available ], and now runs the azihsm_crypto
test suite against real 1.1.

Copilot

Pull request overview

This PR adds dual-build support for azihsm_crypto so it can compile against both OpenSSL 3.x (full functionality with private libctx/provider isolation) and OpenSSL 1.1.x (interim runtime-error stubs to unblock downstream OpenSSL 1.1 engine builds).

Changes:

Adds crates/crypto/build.rs to emit cfg(ossl300) when building against OpenSSL ≥ 3.0.
Refactors libctx plumbing to support OpenSSL 3.x private-libctx isolation while providing a default-context PkeyCtx on OpenSSL 1.1.x.
Gates 3.x-only backends (AES/HMAC/HKDF/RSA/hash) behind cfg(ossl300) and adds Ossl11Unsupported stubs for not(ossl300).

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
crates/crypto/build.rs	Detects OpenSSL version and emits `cfg(ossl300)` for conditional compilation.
crates/crypto/src/lib.rs	Introduces an OpenSSL 1.1.x “unsupported” error and relaxes dead-code linting for interim stubs.
crates/crypto/src/libctx.rs	Splits libctx handling: private libctx for 3.x, default-context `PkeyCtx` for 1.1.x.
crates/crypto/src/hash/hash_ossl.rs	Gates 3.x hash implementation; adds 1.1.x runtime-error stub.
crates/crypto/src/hmac/hmac_ossl.rs	Gates EVP_MAC-based HMAC to 3.x; adds 1.1.x runtime-error stubs.
crates/crypto/src/kdf/hkdf_ossl.rs	Gates HKDF derive to 3.x; adds 1.1.x runtime-error stub.
crates/crypto/src/rsa/rsa_enc_ossl.rs	Gates 3.x RSA encrypt/decrypt implementation; adds 1.1.x runtime-error stubs.
crates/crypto/src/rsa/rsa_sign_ossl.rs	Gates 3.x RSA pre-hash sign/verify/recover; adds 1.1.x runtime-error stubs.
crates/crypto/src/rsa/rsa_hash_sign_ossl.rs	Gates 3.x digest-sign/digest-verify isolation; adds 1.1.x runtime-error stubs.
crates/crypto/src/aes/cbc_ossl.rs	Gates 3.x AES-CBC OpenSSL backend; adds 1.1.x runtime-error stubs.
crates/crypto/src/aes/ecb_ossl.rs	Gates 3.x AES-ECB OpenSSL backend; adds 1.1.x runtime-error stubs.
crates/crypto/src/aes/gcm_ossl.rs	Gates 3.x AES-GCM OpenSSL backend; adds 1.1.x runtime-error stubs.
crates/crypto/src/aes/xts_ossl.rs	Gates 3.x AES-XTS internals; adds 1.1.x runtime-error stub path.

Copilot

Pull request overview

Copilot reviewed 20 out of 32 changed files in this pull request and generated 5 comments.

Copilot

Pull request overview

Copilot reviewed 21 out of 33 changed files in this pull request and generated 5 comments.

Copilot

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 4 comments.

Copilot

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 3 comments.

Copilot

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 7 comments.

azihsm_crypto is OpenSSL-3.x-only (EVP_MAC, OSSL_PARAM, library contexts, provider fetch), which blocks the OpenSSL 1.1.x engine that depends on it transitively via azihsm_api. Add a 1.1.x backend for each algorithm alongside the existing 3.x one, selected at build time: - build.rs emits cfg(ossl300) from the OpenSSL version openssl-sys exposes (DEP_OPENSSL_VERSION_NUMBER). - Each algorithm gains a *_ossl11.rs compiled under cfg(not(ossl300)); the existing *_ossl.rs stays unchanged as the cfg(ossl300) backend. - libctx (private OSSL_LIB_CTX isolation) is gated to 3.x; 1.1 has no library contexts or providers. Covers aes (cbc/ecb/gcm/xts), ecc/ecdh, hash, hmac, kdf/hkdf, and rsa (enc/sign/hash-sign). 3.x is unchanged. Signed-off-by: Christian Walter <christian.walter@9elements.com>

- AES-ECB: move set_padding(false) after encrypt_init. EVP_*Init resets padding to its default (on); OpenSSL 1.1 honors that reset, so the pre-init call was discarded and a block-aligned input got a spurious PKCS#7 block (wrong, over-long ciphertext). Also fixes the AES-KW/KWP and RSA-AES-KW paths, which build on ECB. - HKDF: reject a zero-length output (HkdfDeriveError) and a mismatched Extract-mode length (HmacInvalidDerivedKeyLength), matching the 3.x / CNG backends; the 1.1 EVP_PKEY_HKDF path accepted both silently. The 1.1.x crypto test suite now passes 477/477 (was 458/19); 3.x is unchanged (477/477). Signed-off-by: Christian Walter <christian.walter@9elements.com>

The engine build only compile-checks the crate's 1.1.x crypto backends; run its test suite in the 1.1.1f cell so the 1.1 paths are exercised at runtime, not just compiled. Signed-off-by: Christian Walter <christian.walter@9elements.com>

The restored 1.1.x backends predate three defensive checks the 3.x backends already carry: - HMAC verify: compare with openssl::memcmp::eq after a length check instead of `==`, so verification is constant-time (the module docs already promise this). - AES-CBC: only advance the chaining IV when a full block was produced; an empty input with padding disabled yields count == 0 (encrypt) or a short input (decrypt), which would underflow the slice index and panic. - RSA-PSS: convert the salt length with i32::try_from and error on overflow instead of truncating with `as`. 3.x is unchanged. Signed-off-by: Christian Walter <christian.walter@9elements.com>

Install cargo-nextest from its prebuilt binary (building it from source is unreliable in the 20.04 cell) and run the openssl-engine and azihsm_crypto suites through `cargo nextest run`, matching the runner the 3.x CI already uses. nextest skips doctests, so run azihsm_crypto's doctests in a separate step. Signed-off-by: Christian Walter <christian.walter@9elements.com>

- HKDF: error if OpenSSL returns fewer bytes than requested instead of returning a silently truncated key; the 3.x backend already yields the full requested length. - RSA-OAEP decrypt: map set_rsa_mgf1_md failure to RsaSetPropertyError to match the surrounding OAEP setup calls and the documented error. - Fix a with_pss_padding doc comment that named the parameter hash_algo instead of hash. Signed-off-by: Christian Walter <christian.walter@9elements.com>

- Correct doc comments naming renamed types: OsslRsaSigning -> OsslRsaSignAlgo / OsslRsaHashSignAlgo, OsslHkdf -> OsslHkdfAlgo, and an HMAC module doc describing an OsslHmacKey wrapper / OsslHmacAlgo trait the backend doesn't use (it drives an OpenSSL Signer). - Drop the nonexistent `derived_length` argument from the HKDF new() docs and order the argument list to match the signature. - Pin the engine-matrix cargo-nextest download to 0.9.132 (the version xtask installs) rather than `latest`, for a deterministic install. Signed-off-by: Christian Walter <christian.walter@9elements.com>

Copilot

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 3 comments.

+    /// # Errors
+    ///
+    /// Returns an error if:
+    /// - `CryptoError::RsaSetPropertyError` - Setting padding, OAEP hash algorithm, or label fails
+    /// - `CryptoError::RsaError` - Setting MGF1 hash algorithm fails


+                // Note: IV is updated in the context but not propagated back to the caller
+                // For proper IV chaining in streaming mode, the IV should be the last block of ciphertext


+      # cargo-nextest isn't in the base image and building it from source is
+      # unreliable here; fetch the prebuilt binary, pinned to the version xtask
+      # installs elsewhere (xtask/src/setup.rs CARGO_NEXTEST_VERSION).
+      - name: Install cargo-nextest
+        run: curl -LsSf https://get.nexte.st/0.9.132/linux | tar zxf - -C "${CARGO_HOME:-$HOME/.cargo}/bin"


Copilot AI review requested due to automatic review settings June 30, 2026 06:44

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Comment thread crates/crypto/src/lib.rs Outdated

Comment thread crates/crypto/build.rs Outdated

Comment thread crates/crypto/src/rsa/rsa_sign_ossl.rs Outdated

walterchris force-pushed the engine/crypto-ossl11-compat branch 2 times, most recently from bf8fbdc to df79b29 Compare June 30, 2026 07:49

walterchris added the ossl label Jun 30, 2026

Copilot AI review requested due to automatic review settings July 1, 2026 12:23

walterchris force-pushed the engine/crypto-ossl11-compat branch from df79b29 to 32017ca Compare July 1, 2026 12:23

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Comment thread crates/crypto/src/hmac/hmac_ossl11.rs Outdated

Comment thread crates/crypto/src/hmac/hmac_ossl11.rs Outdated

Comment thread crates/crypto/src/rsa/rsa_sign_ossl11.rs

Comment thread crates/crypto/src/rsa/rsa_hash_sign_ossl11.rs

Comment thread crates/crypto/src/rsa/rsa_sign_ossl11.rs

walterchris changed the title ~~feat(crypto): build azihsm_crypto against OpenSSL 1.1.x (interim 1.1 stubs)~~ feat(crypto): support OpenSSL 1.1.x with per-version backend files Jul 1, 2026

Copilot AI review requested due to automatic review settings July 1, 2026 12:36

walterchris force-pushed the engine/crypto-ossl11-compat branch from 1ca3ac3 to 271afec Compare July 1, 2026 12:36

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Comment thread crates/crypto/src/rsa/rsa_sign_ossl11.rs

Comment thread crates/crypto/src/rsa/rsa_hash_sign_ossl11.rs

Comment thread crates/crypto/src/hmac/hmac_ossl11.rs Outdated

Comment thread crates/crypto/src/hmac/hmac_ossl11.rs Outdated

Comment thread crates/crypto/src/ecc/ecdh_ossl11.rs

walterchris force-pushed the engine/crypto-ossl11-compat branch from 271afec to a2c974b Compare July 1, 2026 16:00

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walterchris force-pushed the engine/crypto-ossl11-compat branch from a2c974b to 949bfdd Compare July 1, 2026 19:29

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Comment thread crates/crypto/src/hmac/hmac_ossl11.rs Outdated

Comment thread crates/crypto/src/hmac/hmac_ossl11.rs Outdated

Comment thread crates/crypto/src/aes/cbc_ossl11.rs Outdated

Comment thread crates/crypto/src/aes/cbc_ossl11.rs Outdated

walterchris requested review from Copilot and rajesh-gali July 2, 2026 07:32

walterchris force-pushed the engine/crypto-ossl11-compat branch from bd166ed to 8658717 Compare July 2, 2026 07:33

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Comment thread crates/crypto/src/kdf/hkdf_ossl11.rs Outdated

Comment thread crates/crypto/src/rsa/rsa_enc_ossl11.rs Outdated

Comment thread crates/crypto/src/rsa/rsa_hash_sign_ossl11.rs Outdated

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walterchris force-pushed the engine/crypto-ossl11-compat branch from fead37c to 23be5d9 Compare July 2, 2026 18:22

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walterchris added 6 commits July 2, 2026 22:43

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walterchris force-pushed the engine/crypto-ossl11-compat branch from 4433b5c to 2c2ee14 Compare July 2, 2026 20:43

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		// Note: IV is updated in the context but not propagated back to the caller
		// For proper IV chaining in streaming mode, the IV should be the last block of ciphertext

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1.1 correctness notes

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walterchris commented Jun 30, 2026 •

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