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Use secp256k1_memclear() to clear stack memory instead of memset()

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All of the invocations of secp256k1_memclear() operate on stack
memory and happen after the function is done with the memory object.
This commit replaces existing memset() invocations and also adds
secp256k1_memclear() to code locations where clearing was missing;
there is no guarantee that this commit covers all code locations
where clearing is necessary.

Co-Authored-By: isle2983 <isle2983@yahoo.com>
This commit is contained in:
Tim Ruffing
2019-06-08 13:54:14 +02:00
committed by Sebastian Falbesoner
parent e3497bbf00
commit 9bb368d146
8 changed files with 23 additions and 21 deletions
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11
src/hash_impl.h
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@@ -156,6 +156,9 @@ static void secp256k1_sha256_finalize(secp256k1_sha256 *hash, unsigned char *out
secp256k1_write_be32(&out32[4*i], hash->s[i]);
hash->s[i] = 0;
}
secp256k1_memclear(sizedesc, sizeof(sizedesc));
secp256k1_memclear(hash, sizeof(secp256k1_sha256));
}
/* Initializes a sha256 struct and writes the 64 byte string
@@ -196,7 +199,7 @@ static void secp256k1_hmac_sha256_initialize(secp256k1_hmac_sha256 *hash, const
rkey[n] ^= 0x5c ^ 0x36;
}
secp256k1_sha256_write(&hash->inner, rkey, sizeof(rkey));
memset(rkey, 0, sizeof(rkey));
secp256k1_memclear(rkey, sizeof(rkey));
}
static void secp256k1_hmac_sha256_write(secp256k1_hmac_sha256 *hash, const unsigned char *data, size_t size) {
@@ -207,7 +210,7 @@ static void secp256k1_hmac_sha256_finalize(secp256k1_hmac_sha256 *hash, unsigned
unsigned char temp[32];
secp256k1_sha256_finalize(&hash->inner, temp);
secp256k1_sha256_write(&hash->outer, temp, 32);
memset(temp, 0, 32);
secp256k1_memclear(temp, sizeof(temp));
secp256k1_sha256_finalize(&hash->outer, out32);
}
@@ -274,9 +277,7 @@ static void secp256k1_rfc6979_hmac_sha256_generate(secp256k1_rfc6979_hmac_sha256
}
static void secp256k1_rfc6979_hmac_sha256_finalize(secp256k1_rfc6979_hmac_sha256 *rng) {
memset(rng->k, 0, 32);
memset(rng->v, 0, 32);
rng->retry = 0;
secp256k1_memclear(rng, sizeof(secp256k1_rfc6979_hmac_sha256));
}
#undef Round