Beispiel #1
0
        /// <summary>
        /// Verifies a signature of <paramref name="Data"/> made by the EdDSA algorithm.
        /// </summary>
        /// <param name="Data">Payload to sign.</param>
        /// <param name="PublicKey">Public Key of the entity that generated the signature.</param>
        /// <param name="HashFunction">Hash function to use.</param>
        /// <param name="Curve">Elliptic curve</param>
        /// <param name="Signature">Signature</param>
        /// <returns>If the signature is valid.</returns>
        public static bool Verify(Stream Data, byte[] PublicKey, HashFunctionStream HashFunction,
                                  EdwardsCurveBase Curve, byte[] Signature)
        {
            try
            {
                int ScalarBytes = Signature.Length;
                if ((ScalarBytes & 1) != 0)
                {
                    return(false);
                }

                ScalarBytes >>= 1;

                byte[] R = new byte[ScalarBytes];
                Array.Copy(Signature, 0, R, 0, ScalarBytes);
                PointOnCurve r = Decode(R, Curve);
                byte[]       S = new byte[ScalarBytes];
                Array.Copy(Signature, ScalarBytes, S, 0, ScalarBytes);
                BigInteger s = EllipticCurve.ToInt(S);
                byte[]     h;

                if (s >= Curve.Order)
                {
                    return(false);
                }

                using (TemporaryStream TempFile = new TemporaryStream())        // dom2(F, C) = blank string
                {
                    TempFile.Write(R, 0, ScalarBytes);
                    TempFile.Write(PublicKey, 0, ScalarBytes);

                    Data.Position = 0;
                    Data.CopyTo(TempFile);                                  // PH(M)=M

                    TempFile.Position = 0;
                    h = HashFunction(TempFile);
                }

                BigInteger   k  = BigInteger.Remainder(EllipticCurve.ToInt(h), Curve.Order);
                PointOnCurve P1 = Curve.ScalarMultiplication(s, Curve.BasePoint, false);
                PointOnCurve P2 = Curve.ScalarMultiplication(k, Curve.Decode(PublicKey), false);
                Curve.AddTo(ref P2, r);

                P1.Normalize(Curve);
                P2.Normalize(Curve);

                return(P1.Equals(P2));
            }
            catch (ArgumentException)
            {
                return(false);
            }
        }
Beispiel #2
0
        /// <summary>
        /// Verifies a signature of <paramref name="Data"/> made by the EdDSA algorithm.
        /// </summary>
        /// <param name="Data">Payload to sign.</param>
        /// <param name="PublicKey">Public Key of the entity that generated the signature.</param>
        /// <param name="HashFunction">Hash function to use.</param>
        /// <param name="Curve">Elliptic curve</param>
        /// <param name="Signature">Signature</param>
        /// <returns>If the signature is valid.</returns>
        public static bool Verify(byte[] Data, byte[] PublicKey, HashFunctionArray HashFunction,
                                  EdwardsCurveBase Curve, byte[] Signature)
        {
            try
            {
                int ScalarBytes = Signature.Length;
                if ((ScalarBytes & 1) != 0)
                {
                    return(false);
                }

                ScalarBytes >>= 1;

                byte[] R = new byte[ScalarBytes];
                Array.Copy(Signature, 0, R, 0, ScalarBytes);
                PointOnCurve r = Decode(R, Curve);
                byte[]       S = new byte[ScalarBytes];
                Array.Copy(Signature, ScalarBytes, S, 0, ScalarBytes);
                BigInteger s = EllipticCurve.ToInt(S);

                if (s >= Curve.Order)
                {
                    return(false);
                }

                int    c   = Data.Length;
                byte[] Bin = new byte[(ScalarBytes << 1) + c];              // dom2(F, C) = blank string
                Array.Copy(R, 0, Bin, 0, ScalarBytes);
                Array.Copy(PublicKey, 0, Bin, ScalarBytes, ScalarBytes);
                Array.Copy(Data, 0, Bin, ScalarBytes << 1, c);              // PH(M)=M

                byte[] h = HashFunction(Bin);

                BigInteger   k  = BigInteger.Remainder(EllipticCurve.ToInt(h), Curve.Order);
                PointOnCurve P1 = Curve.ScalarMultiplication(s, Curve.BasePoint, false);
                PointOnCurve P2 = Curve.ScalarMultiplication(k, Curve.Decode(PublicKey), false);
                Curve.AddTo(ref P2, r);

                P1.Normalize(Curve);
                P2.Normalize(Curve);

                return(P1.Equals(P2));
            }
            catch (ArgumentException)
            {
                return(false);
            }
        }