private static byte[] DecryptBytes(Compact.Iterator parts, object key, JweAlgorithm?jweAlg, JweEncryption?jweEnc, JwtSettings settings = null)
{
byte[] header = parts.Next();
byte[] encryptedCek = parts.Next();
byte[] iv = parts.Next();
byte[] cipherText = parts.Next();
byte[] authTag = parts.Next();
JwtSettings jwtSettings = GetSettings(settings);
IDictionary <string, object> jwtHeader = jwtSettings.JsonMapper.Parse <Dictionary <string, object> >(Encoding.UTF8.GetString(header));
JweAlgorithm headerAlg = jwtSettings.JwaAlgorithmFromHeader((string)jwtHeader["alg"]);
JweEncryption headerEnc = jwtSettings.JweAlgorithmFromHeader((string)jwtHeader["enc"]);
IKeyManagement keys = jwtSettings.Jwa(headerAlg);
IJweAlgorithm enc = jwtSettings.Jwe(headerEnc);
if (keys == null)
{
throw new JoseException(string.Format("Unsupported JWA algorithm requested: {0}", headerAlg));
}
if (enc == null)
{
throw new JoseException(string.Format("Unsupported JWE algorithm requested: {0}", headerEnc));
}
if (jweAlg != null && (JweAlgorithm)jweAlg != headerAlg)
{
throw new InvalidAlgorithmException("The algorithm type passed to the Decrypt method did not match the algorithm type in the header.");
}
if (jweEnc != null && (JweEncryption)jweEnc != headerEnc)
{
throw new InvalidAlgorithmException("The encryption type passed to the Decrypt method did not match the encryption type in the header.");
}
byte[] cek = keys.Unwrap(encryptedCek, key, enc.KeySize, jwtHeader);
byte[] aad = Encoding.UTF8.GetBytes(Compact.Serialize(header));
byte[] plainText = enc.Decrypt(aad, cek, iv, cipherText, authTag);
if (jwtHeader.ContainsKey("zip"))
{
ICompression compression = jwtSettings.Compression((string)jwtHeader["zip"]);
plainText = compression.Decompress(plainText);
}
return(plainText);
}
