absl::Status KmsPrehashedSigner::Sign()

in kmsp11/operation/kms_prehashed_signer.cc [24:69]
41 lines of code
6 McCabe index (conditional complexity)

absl::Status KmsPrehashedSigner::Sign(KmsClient* client,
                                      absl::Span<const uint8_t> digest,
                                      absl::Span<uint8_t> signature) {
  ASSIGN_OR_RETURN(const EVP_MD* md,
                   DigestForMechanism(*object_->algorithm().digest_mechanism));

  if (digest.size() != EVP_MD_size(md)) {
    return NewInvalidArgumentError(
        absl::StrFormat("provided digest has incorrect size (got %d, want %d)",
                        digest.size(), EVP_MD_size(md)),
        CKR_DATA_LEN_RANGE, SOURCE_LOCATION);
  }

  if (signature.size() != signature_length()) {
    return NewInternalError(
        absl::StrFormat(
            "provided signature buffer has incorrect size (got %d, want %d)",
            signature.size(), signature_length()),
        SOURCE_LOCATION);
  }

  kms_v1::AsymmetricSignRequest req;
  req.set_name(std::string(object_->kms_key_name()));

  int digest_nid = EVP_MD_type(md);
  switch (digest_nid) {
    case NID_sha256:
      req.mutable_digest()->set_sha256(digest.data(), digest.size());
      break;
    case NID_sha384:
      req.mutable_digest()->set_sha384(digest.data(), digest.size());
      break;
    case NID_sha512:
      req.mutable_digest()->set_sha512(digest.data(), digest.size());
      break;
    default:
      return NewInternalError(
          absl::StrFormat("unhandled digest type: %d", digest_nid),
          SOURCE_LOCATION);
  }

  ASSIGN_OR_RETURN(kms_v1::AsymmetricSignResponse resp,
                   client->AsymmetricSign(req));
  RETURN_IF_ERROR(CopySignature(resp.signature(), signature));
  return absl::OkStatus();
}