EVP_DigestVerifyUpdate
if (EVP_DigestVerifyUpdate(ctx, tbs, tbslen) <= 0)
CHECK_GOTO(EVP_DigestVerifyUpdate(md_ctx_verify, kMsg, sizeof(kMsg)));
CHECK_GOTO(EVP_DigestVerifyUpdate(md_ctx_verify, input, strlen(input)));
ret = EVP_DigestVerifyUpdate(dsa->dsa_ctx, buf, len);