Re: gost hash

Nikos Mavrogiannopoulos nmav@gnutls.org writes:

Attached is an updated version of the patch.

+void +gosthash94_digest (gosthash94_ctx * ctx, unsigned length, uint8_t *result) +{

• unsigned index = ctx->length & 31;
• uint32_t *msg32 = (uint32_t*)ctx->message;
• assert(length <= GOSTHASH94_DIGEST_SIZE);
• /* pad the last block with zeroes and hash it */
• if (index > 0)

•  {
  

•      memset (ctx->message + index, 0, 32 - index);
  

•      gost_compute_sum_and_hash (ctx, ctx->message);
  

•  }
  

• /* hash the message length and the sum */
• msg32[0] = (uint32_t) (ctx->length << 3);
• msg32[1] = (uint32_t) (ctx->length >> 29);
• memset (msg32 + 2, 0, sizeof (uint32_t) * 6);
• gost_block_compress (ctx, msg32);
• gost_block_compress (ctx, ctx->sum);
• /* convert hash state to result bytes */
• _nettle_write_le32(length, result, ctx->hash);

+}

Any good reason for reusing the ctx->message as msg32? The cast looks dangerous, even if maybe it isn't (potentially it could have bad alignment, but not with the current struct layout). I'd replace that with a local array,

uint32_t msg32[8];

Also, the _digest function should reset the state when it's done, in the same way as _init. Which is easy, just call _init, or memset directly.

Regards, /Niels