absl::Status KmsDigestingSigner::Sign()

in kmsp11/operation/kms_digesting_signer.cc [34:71]
34 lines of code
5 McCabe index (conditional complexity)

absl::Status KmsDigestingSigner::Sign(KmsClient* client,
                                      absl::Span<const uint8_t> data,
                                      absl::Span<uint8_t> signature) {
  if (md_ctx_) {
    return FailedPreconditionError(
        "Sign cannot be used to terminate a multi-part signing operation",
        CKR_FUNCTION_FAILED, SOURCE_LOCATION);
  }

  const size_t md_size = EVP_MD_size(md_);
  std::vector<uint8_t> evp_digest(md_size);
  unsigned int digest_len;
  bssl::UniquePtr<EVP_MD_CTX> ctx(EVP_MD_CTX_new());
  if (EVP_Digest(data.data(), data.size(), evp_digest.data(), &digest_len, md_,
                 nullptr) != 1) {
    return NewInternalError(
        absl::StrFormat(
            "failed while computing EVP digest with digest size %d: %s",
            md_size, SslErrorToString()),
        SOURCE_LOCATION);
  }

  if (digest_len != md_size) {
    return NewInternalError(
        absl::StrFormat(
            "computed digest has incorrect size (got %d, want %d): %s",
            digest_len, md_size, SslErrorToString()),
        SOURCE_LOCATION);
  }

  if (IsRawRsaAlgorithm(object()->algorithm().algorithm)) {
    ASSIGN_OR_RETURN(std::vector<uint8_t> digest_info,
                     BuildRsaDigestInfo(EVP_MD_type(md_), evp_digest));
    return inner_signer_->Sign(client, digest_info, signature);
  }

  return inner_signer_->Sign(client, evp_digest, signature);
}