/// <summary>
/// Constructs the token for validating an incoming request.
/// </summary>
public HttpSignatureSecurityToken(string rawDigest, string rawSignature)
{
RawDigest = rawDigest;
RawSignature = rawSignature;
Digest = HttpDigest.Parse(rawDigest);
Signature = HttpSignature.Parse(rawSignature);
}
/// <summary>
/// constructs the token for sending a request with http signature.
/// </summary>
/// <param name="signingCredentials"></param>
/// <param name="requestBody"></param>
/// <param name="includedHeaders"></param>
/// <param name="createdDate"></param>
/// <param name="expirationDate"></param>
public HttpSignatureSecurityToken(SigningCredentials signingCredentials, byte[] requestBody, IDictionary <string, string> includedHeaders, DateTime?createdDate = null, DateTime?expirationDate = null)
{
Digest = new HttpDigest(signingCredentials.Algorithm, requestBody);
includedHeaders.Add(HttpDigest.HTTPHeaderName, Digest.ToString());
Signature = new HttpSignature(signingCredentials, includedHeaders, createdDate, expirationDate);
RequestId = includedHeaders["X-Request-Id"];
}
/// <summary>
/// Parses the header value string into an <see cref="HttpDigest"/> instance.
/// </summary>
/// <param name="headerValue"></param>
/// <returns></returns>
public static HttpDigest Parse(string headerValue)
{
var equalsSignPosition = headerValue.IndexOf('='); // do not use split because base64 uses the equals sign.
if (equalsSignPosition < 0)
{
throw new FormatException($"Cannot parse HttpDigest from raw value {headerValue}");
}
var digest = new HttpDigest {
Algorithm = headerValue.Substring(0, equalsSignPosition),
Output = headerValue.Substring(equalsSignPosition + 1),
};
return(digest);
}
private async Task ValidateResponse(HttpRequestMessage request, HttpResponseMessage response)
{
if (IgnoreResponseValidation)
{
return;
}
if (StringExtensions.IsIgnoredPath(IgnoredPaths, request.RequestUri.AbsolutePath, request.Method.Method))
{
return;
}
if (!response.Headers.TryGetValues(HttpSignature.HTTPHeaderName, out var signatureValues) || signatureValues.Count() == 0)
{
return;
}
if (!response.Headers.TryGetValues(ResponseSignatureCertificateHeaderName, out var certValues) || certValues.Count() == 0)
{
var error = $"Missing certificate in HTTP header '{ResponseSignatureCertificateHeaderName}'. Cannot validate signature.";
throw new Exception(error);
}
var rawSignature = signatureValues.First();
var rawCertificate = certValues.First();
Debug.WriteLine($"{nameof(HttpSignatureDelegatingHandler)}: Raw Signature: {rawSignature}");
Debug.WriteLine($"{nameof(HttpSignatureDelegatingHandler)}: Raw Certificate: {rawCertificate}");
X509Certificate2 certificate;
try {
certificate = new X509Certificate2(Convert.FromBase64String(rawCertificate));
} catch (Exception inner) {
var error = $"Signature Certificate not in a valid format. Expected a base64 encoded x509.";
throw new Exception(error, inner);
}
var validationKey = new X509SecurityKey(certificate);
Debug.WriteLine($"{nameof(HttpSignatureDelegatingHandler)}: Validation Key: {validationKey.KeyId}");
var httpSignature = HttpSignature.Parse(rawSignature);
if (response.Headers.TryGetValues(HttpDigest.HTTPHeaderName, out var digestValues) && digestValues.Count() > 0)
{
var rawDigest = digestValues.First();
Debug.WriteLine($"{nameof(HttpSignatureDelegatingHandler)}: Raw Digest: {rawDigest}");
var httpDigest = HttpDigest.Parse(rawDigest);
Debug.WriteLine($"{nameof(HttpSignatureDelegatingHandler)}: Validated Token Digest: {httpDigest}");
var responseBody = await response.Content.ReadAsByteArrayAsync();
// Validate the request.
var disgestIsValid = httpDigest.Validate(responseBody);
if (!disgestIsValid)
{
var error = $"Response digest validation failed.";
throw new Exception(error);
}
}
response.Headers.TryGetValues(ResponseCreatedHeaderName, out var createdFieldValue);
var signatureIsValid = httpSignature.Validate(validationKey, request.RequestUri, request.Method.Method, createdFieldValue.First(), response.Headers);
if (!signatureIsValid)
{
var error = $"Response signature validation failed.";
throw new Exception(error);
}
}
