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exports.c: add blst_fp_from_{lb}e_bytes. #272

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exports.c: add blst_fp_from_{lb}e_bytes. #272

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8ceb1f7
exports.c: add blst_fp_from_{lb}e_bytes.
dot-asm Oct 24, 2025
2b9bf4b
exports.c: foolproof blst_fr_from_{lb}e_bytes.
dot-asm Oct 26, 2025
73b4021
Execute build/refresh.sh.
dot-asm Oct 27, 2025
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3 changes: 3 additions & 0 deletions bindings/blst_aux.h
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Original file line number Diff line number Diff line change
Expand Up @@ -110,6 +110,9 @@ size_t blst_p2_sizeof(void);
size_t blst_p2_affine_sizeof(void);
size_t blst_fp12_sizeof(void);

void blst_fp_from_le_bytes(blst_fp *ret, const byte *in, size_t len);
void blst_fp_from_be_bytes(blst_fp *ret, const byte *in, size_t len);

/*
* Single-shot SHA-256 hash function.
*/
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6 changes: 6 additions & 0 deletions bindings/rust/src/bindings.rs
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Expand Up @@ -1386,6 +1386,12 @@ extern "C" {
extern "C" {
pub fn blst_fp12_sizeof() -> usize;
}
extern "C" {
pub fn blst_fp_from_le_bytes(ret: *mut blst_fp, in_: *const byte, len: usize);
}
extern "C" {
pub fn blst_fp_from_be_bytes(ret: *mut blst_fp, in_: *const byte, len: usize);
}
extern "C" {
pub fn blst_sha256(out: *mut byte, msg: *const byte, msg_len: usize);
}
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41 changes: 39 additions & 2 deletions src/exports.c
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Expand Up @@ -497,7 +497,7 @@ void blst_uint64_from_fr(unsigned long long ret[4], const vec256 a)

int blst_scalar_from_le_bytes(pow256 out, const unsigned char *bytes, size_t n)
{
size_t rem = (n - 1) % 32 + 1;
size_t rem = n ? ((n - 1) % 32 + 1) : 0;
struct { vec256 out, digit; } t;
limb_t ret;

Expand Down Expand Up @@ -525,7 +525,7 @@ int blst_scalar_from_le_bytes(pow256 out, const unsigned char *bytes, size_t n)

int blst_scalar_from_be_bytes(pow256 out, const unsigned char *bytes, size_t n)
{
size_t rem = (n - 1) % 32 + 1;
size_t rem = n ? ((n - 1) % 32 + 1) : 0;
struct { vec256 out, digit; } t;
limb_t ret;

Expand All @@ -550,6 +550,43 @@ int blst_scalar_from_be_bytes(pow256 out, const unsigned char *bytes, size_t n)
return (int)(ret^1);
}

void blst_fp_from_le_bytes(vec384 out, const unsigned char *bytes, size_t n)
{
size_t rem = n ? ((n - 1) % 48 + 1) : 0;
vec384 digit;

vec_zero(out, sizeof(vec384));

n -= rem;
limbs_from_le_bytes(out, bytes += n, rem);
mul_mont_384(out, BLS12_381_RR, out, BLS12_381_P, p0);

while (n) {
limbs_from_le_bytes(digit, bytes -= 48, 48);
add_mod_384(out, out, digit, BLS12_381_P);
mul_mont_384(out, BLS12_381_RR, out, BLS12_381_P, p0);
n -= 48;
}
}

void blst_fp_from_be_bytes(vec384 out, const unsigned char *bytes, size_t n)
{
size_t rem = n ? ((n - 1) % 48 + 1) : 0;
vec384 digit;

vec_zero(out, sizeof(vec384));

limbs_from_be_bytes(out, bytes, rem);
mul_mont_384(out, BLS12_381_RR, out, BLS12_381_P, p0);

while (n -= rem) {
limbs_from_be_bytes(digit, bytes += rem, 48);
add_mod_384(out, out, digit, BLS12_381_P);
mul_mont_384(out, BLS12_381_RR, out, BLS12_381_P, p0);
rem = 48;
}
}

/*
* Single-short SHA-256 hash function.
*/
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