Exemple #1
0
        public static byte[] Hash(byte[] data, int offset, int count)
        {
            Sha512 hasher = new Sha512();

            hasher.Update(data, offset, count);
            return(hasher.Finish());
        }
        public static void KeyExchange(ArraySegment <byte> sharedKey, ArraySegment <byte> publicKey,
                                       ArraySegment <byte> privateKey)
        {
            if (sharedKey.Array == null)
            {
                throw new ArgumentNullException(nameof(sharedKey));
            }

            if (publicKey.Array == null)
            {
                throw new ArgumentNullException(nameof(sharedKey));
            }

            if (privateKey.Array == null)
            {
                throw new ArgumentNullException("privateKey");
            }

            if (sharedKey.Count != 32)
            {
                throw new ArgumentException("sharedKey.Count != 32");
            }

            if (publicKey.Count != 32)
            {
                throw new ArgumentException("publicKey.Count != 32");
            }

            if (privateKey.Count != 64)
            {
                throw new ArgumentException("privateKey.Count != 64");
            }

            FieldOperations.fe_frombytes(out FieldElement edwardsY, publicKey.Array, publicKey.Offset);
            FieldOperations.fe_1(out FieldElement edwardsZ);
            MontgomeryCurve25519.EdwardsToMontgomeryX(out FieldElement montgomeryX, ref edwardsY, ref edwardsZ);
            byte[] h = Sha512.Hash(privateKey.Array, privateKey.Offset, 32);
            ScalarOperations.ScClamp(h, 0);
            MontgomeryOperations.ScalarMult(out FieldElement sharedMontgomeryX, h, 0, ref montgomeryX);
            CryptoBytes.Wipe(h);
            FieldOperations.fe_tobytes(sharedKey.Array, sharedKey.Offset, ref sharedMontgomeryX);
            MontgomeryCurve25519.KeyExchangeOutputHashNaCl(sharedKey.Array, sharedKey.Offset);
        }