Esempio n. 1
0
        internal static BigInteger ComputeX(ClientInfo clientInfo, SrpInfo srpInfo)
        {
            var method     = srpInfo.SrpMethod;
            var iterations = srpInfo.Iterations;

            if (iterations == 0)
            {
                throw new UnsupportedFeatureException("0 iterations is not supported");
            }

            // TODO: Add constants for 1024, 6144 and 8192
            if (method != "SRPg-4096")
            {
                throw new UnsupportedFeatureException($"Method '{method}' is not supported");
            }

            var k1 = Util.Hkdf(method: method,
                               ikm: srpInfo.Salt,
                               salt: clientInfo.Username.ToBytes());
            var k2 = Util.Pbes2(method: srpInfo.KeyMethod,
                                password: clientInfo.Password,
                                salt: k1,
                                iterations: iterations);
            var x = clientInfo.AccountKey.CombineWith(k2);

            return(x.ToBigInt());
        }
Esempio n. 2
0
        //
        // Internal
        //

        internal static byte[] Perform(BigInteger secretA,
                                       ClientInfo clientInfo,
                                       SrpInfo srpInfo,
                                       string sessionId,
                                       RestClient rest)
        {
            var sharedA = ComputeSharedA(secretA);
            var sharedB = ExchangeAForB(sharedA, sessionId, rest);

            ValidateB(sharedB);
            return(ComputeKey(secretA, sharedA, sharedB, clientInfo, srpInfo, sessionId));
        }
Esempio n. 3
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        internal static byte[] ComputeKey(BigInteger secretA,
                                          BigInteger sharedA,
                                          BigInteger sharedB,
                                          ClientInfo clientInfo,
                                          SrpInfo srpInfo,
                                          string sessionId)
        {
            // Some arbitrary crypto computation, variable names don't have a lot of meaning
            var ab     = sharedA.ToHex() + sharedB.ToHex();
            var hashAb = Crypto.Sha256(ab).ToBigInt();
            var s      = sessionId.ToBytes().ToBigInt();
            var x      = ComputeX(clientInfo, srpInfo);
            var y      = sharedB - SirpG.ModExp(x, SirpN) * s;
            var z      = y.ModExp(secretA + hashAb * x, SirpN);

            return(Crypto.Sha256(z.ToHex()));
        }
Esempio n. 4
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        // Returns the session encryption key
        public static AesKey Perform(ClientInfo clientInfo, SrpInfo srpInfo, string sessionId, RestClient rest)
        {
            var key = Perform(GenerateSecretA(), clientInfo, srpInfo, sessionId, rest);

            return(new AesKey(sessionId, key));
        }