public override SignatureVerificationFailure VerifySync(HttpRequestForSigning signedRequest, Signature signature, Client client)
{
if (signature.Headers.Contains(HeaderName.PredefinedHeaderNames.Digest) &&
!signedRequest.Headers.Contains(HeaderName.PredefinedHeaderNames.Digest))
{
return(SignatureVerificationFailure.HeaderMissing($"The {HeaderName.PredefinedHeaderNames.Digest} header is indicated as part of the signature, but it is not included in the request."));
}
if (!signedRequest.Headers.Contains(HeaderName.PredefinedHeaderNames.Digest))
{
_logger?.LogDebug("{0} header verification is not required, because it is not present in the request to verify.", HeaderName.PredefinedHeaderNames.Digest);
return(null);
}
if (signedRequest.Body == null)
{
return(SignatureVerificationFailure.InvalidDigestHeader($"The {HeaderName.PredefinedHeaderNames.Digest} header verification failed. The request has no body."));
}
var digestHeaderValue = signedRequest.Headers.GetValues(HeaderName.PredefinedHeaderNames.Digest).FirstOrDefault();
var digestParams = new List <string>();
if (!string.IsNullOrEmpty(digestHeaderValue))
{
var separatorIndex = digestHeaderValue.IndexOf('=');
if (separatorIndex < 0 || separatorIndex >= digestHeaderValue.Length - 1)
{
digestParams.Add(digestHeaderValue);
}
else
{
digestParams.Add(digestHeaderValue.Substring(0, separatorIndex));
digestParams.Add(digestHeaderValue.Substring(separatorIndex + 1));
}
}
if (digestParams.Count < 2)
{
return(SignatureVerificationFailure.InvalidDigestHeader($"The {HeaderName.PredefinedHeaderNames.Digest} request header is invalid."));
}
if (!Constants.DigestHashAlgorithms.TryGetValue(digestParams[0], out var digestAlgorithmName))
{
return(SignatureVerificationFailure.InvalidDigestHeader($"The {HeaderName.PredefinedHeaderNames.Digest} algorithm name ({digestParams[0] ?? "[null]"}) is invalid."));
}
using (var hashAlgorithm = HashAlgorithmFactory.Create(new HashAlgorithmName(digestAlgorithmName))) {
if (hashAlgorithm == null)
{
return(SignatureVerificationFailure.InvalidDigestHeader($"The {HeaderName.PredefinedHeaderNames.Digest} algorithm name ({digestParams[0] ?? "[null]"}) is currently not supported."));
}
var payloadBytes = hashAlgorithm.ComputeHash(signedRequest.Body);
var calculatedDigest = _base64Converter.ToBase64(payloadBytes);
var receivedDigest = digestParams[1];
if (calculatedDigest != receivedDigest)
{
return(SignatureVerificationFailure.InvalidDigestHeader("The digest header verification failed."));
}
}
return(null);
}