Hash algorithms

[maths644311798]

In yacl/crypto/base/hash/hash_interface.h, the following code means a recommendation of some hash algorithms.

enum class HashAlgorithm : int {
UNKNOWN,
// SHA-2 family of algorithms
SHA224 = 1,
SHA256 = 2,
SHA384 = 3,
SHA512 = 4,

SHA_1 = 5,

SM3 = 6,

BLAKE2B = 7,
BLAKE3 = 8
};

My first question is : Why not use SHA3 since SHA1 is not safe?

The second question comes from the following code in hmac.cc:

void Init_HMAC(HashAlgorithm hash_algo, ByteContainerView key,
HMAC_CTX* context) {
int res = 0;
switch (hash_algo) {
case HashAlgorithm::SHA224:
res =
HMAC_Init_ex(context, key.data(), key.size(), EVP_sha224(), nullptr);
break;
case HashAlgorithm::SHA256:
res =
HMAC_Init_ex(context, key.data(), key.size(), EVP_sha256(), nullptr);
break;
case HashAlgorithm::SHA384:
res =
HMAC_Init_ex(context, key.data(), key.size(), EVP_sha384(), nullptr);
break;
case HashAlgorithm::SHA512:
res =
HMAC_Init_ex(context, key.data(), key.size(), EVP_sha512(), nullptr);
break;
case HashAlgorithm::SHA_1:
res = HMAC_Init_ex(context, key.data(), key.size(), EVP_sha1(), nullptr);
break;
case HashAlgorithm::SM3:
res = HMAC_Init_ex(context, key.data(), key.size(), EVP_sm3(), nullptr);
break;
case HashAlgorithm::UNKNOWN:
default:
YACL_THROW("Unsupported hash algo: {}", static_cast(hash_algo));
break;
}

YACL_ENFORCE_EQ(res, 1, "Failed to HMAC_Init_ex.");
}

Why is BLAKE not written here?

[Jamie-Cui]

Why not use SHA3 since SHA1 is not safe?

Yes, sha3 is supposed to be more secure than sha1 (we'll include a security warning for sha1 or remove sha1 in the future).

Why is BLAKE not written here?

Since there are so many crypto protocols/primitives/tools in the wild, we are not able to include everything in our repo. Therefore, we follow a simple yet efficient logic for adding new algorithms in yacl/crypto/base:

We only include new algorithms when necessary (and the algorithm should be standardised in some way)

Above codes are sufficient for most of yacl's use case as far as I am aware of. However, if in your case blake family is a must, please feel free to submit a PR, will really appreciate that. :P

[maths644311798]

Thanks. The strange point is that BLAKE is in hash_interface.h but not in hmac.cc.

[Jamie-Cui]

Indeed, the truth is that we only write simple wrapper for those standardised algorithms, as to support other higher-level protocols. If you are using standard PKI more often, I strongly recommend use OpenSSL directly.