frost/secp256k1-zkp
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Split memclear into two versions

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secp256k1_memclear has the side effect of undefining bytes for
valgrind checks. In some cases, we may want to zero bytes
but allow subsequent reads. So we split memclear into
memclear_explicit, which makes no guarantees about the content
of the buffer on return, and memzero_explicit, which guarantees
zero value on return.

Change the memset in partial_sign to use memzero_explicit.
This commit is contained in:
John Moffett
2025-09-08 12:21:48 -04:00
parent 4985ac0f89
commit 399b582a5f
11 changed files with 41 additions and 28 deletions
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8
src/ecmult_gen_impl.h
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@@ -277,8 +277,8 @@ static void secp256k1_ecmult_gen(const secp256k1_ecmult_gen_context *ctx, secp25
/* Cleanup. */
secp256k1_fe_clear(&neg);
secp256k1_ge_clear(&add);
secp256k1_memclear(&adds, sizeof(adds));
secp256k1_memclear(&recoded, sizeof(recoded));
secp256k1_memclear_explicit(&adds, sizeof(adds));
secp256k1_memclear_explicit(&recoded, sizeof(recoded));
}
/* Setup blinding values for secp256k1_ecmult_gen. */
@@ -310,7 +310,7 @@ static void secp256k1_ecmult_gen_blind(secp256k1_ecmult_gen_context *ctx, const
VERIFY_CHECK(seed32 != NULL);
memcpy(keydata + 32, seed32, 32);
secp256k1_rfc6979_hmac_sha256_initialize(&rng, keydata, 64);
secp256k1_memclear(keydata, sizeof(keydata));
secp256k1_memclear_explicit(keydata, sizeof(keydata));
/* Compute projective blinding factor (cannot be 0). */
secp256k1_rfc6979_hmac_sha256_generate(&rng, nonce32, 32);
@@ -331,7 +331,7 @@ static void secp256k1_ecmult_gen_blind(secp256k1_ecmult_gen_context *ctx, const
secp256k1_ge_set_gej(&ctx->ge_offset, &gb);
/* Clean up. */
secp256k1_memclear(nonce32, sizeof(nonce32));
secp256k1_memclear_explicit(nonce32, sizeof(nonce32));
secp256k1_scalar_clear(&b);
secp256k1_gej_clear(&gb);
secp256k1_fe_clear(&f);