private static string SecureInput(Dictionary <string, object> header, Dictionary <string, object> payload)
{
string encodeHeader = UrlBase64.Encode(Encoding.UTF8.GetBytes(JSON.Serialize(header)));
string encodePayload = UrlBase64.Encode(Encoding.UTF8.GetBytes(JSON.Serialize(payload)));
return(String.Format("{0}.{1}", encodeHeader, encodePayload));
}
/// <summary>
/// Generates a Jws Signature.
/// </summary>
/// <param name="header"></param>
/// <param name="payload"></param>
/// <returns></returns>
public string GenerateSignature(Dictionary <string, object> header, Dictionary <string, object> payload)
{
string securedInput = SecureInput(header, payload);
byte[] message = Encoding.UTF8.GetBytes(securedInput);
using (var sha256Hasher = SHA256.Create())
{
byte[] hashedMessage = sha256Hasher.ComputeHash(message);
ECDsaSigner signer = new ECDsaSigner();
signer.Init(true, _privateKey);
BigInteger[] results = signer.GenerateSignature(hashedMessage);
// Concated to create signature
var a = results[0].ToByteArrayUnsigned();
var b = results[1].ToByteArrayUnsigned();
// a,b are required to be exactly the same length of bytes
if (a.Length != b.Length)
{
int largestLength = Math.Max(a.Length, b.Length);
a = ByteArrayPadLeft(a, largestLength);
b = ByteArrayPadLeft(b, largestLength);
}
string signature = UrlBase64.Encode(a.Concat(b).ToArray());
return(String.Format("{0}.{1}", securedInput, signature));
}
}
