// 5.4 pg 29 /** * return true if the value r and s represent a DSA signature for * the passed in message (for standard DSA the message should be * a SHA-1 hash of the real message to be verified). */ public virtual bool VerifySignature(byte[] message, BigInteger r, BigInteger s) { BigInteger n = key.Parameters.N; // r and s should both in the range [1,n-1] if (r.SignValue < 1 || s.SignValue < 1 || r.CompareTo(n) >= 0 || s.CompareTo(n) >= 0) { return false; } BigInteger e = CalculateE(n, message); BigInteger c = s.ModInverse(n); BigInteger u1 = e.Multiply(c).Mod(n); BigInteger u2 = r.Multiply(c).Mod(n); ECPoint G = key.Parameters.G; ECPoint Q = ((ECPublicKeyParameters) key).Q; ECPoint point = ECAlgorithms.SumOfTwoMultiplies(G, u1, Q, u2).Normalize(); if (point.IsInfinity) return false; BigInteger v = point.AffineXCoord.ToBigInteger().Mod(n); return v.Equals(r); }
/** * return true if the value r and s represent a DSA signature for * the passed in message for standard DSA the message should be a * SHA-1 hash of the real message to be verified. */ public virtual bool VerifySignature(byte[] message, BigInteger r, BigInteger s) { DsaParameters parameters = key.Parameters; BigInteger q = parameters.Q; BigInteger m = CalculateE(q, message); if (r.SignValue <= 0 || q.CompareTo(r) <= 0) { return false; } if (s.SignValue <= 0 || q.CompareTo(s) <= 0) { return false; } BigInteger w = s.ModInverse(q); BigInteger u1 = m.Multiply(w).Mod(q); BigInteger u2 = r.Multiply(w).Mod(q); BigInteger p = parameters.P; u1 = parameters.G.ModPow(u1, p); u2 = ((DsaPublicKeyParameters)key).Y.ModPow(u2, p); BigInteger v = u1.Multiply(u2).Mod(p).Mod(q); return v.Equals(r); }
/** * return true if the value r and s represent a GOST3410 signature for * the passed in message (for standard GOST3410 the message should be * a GOST3411 hash of the real message to be verified). */ public bool VerifySignature( byte[] message, BigInteger r, BigInteger s) { byte[] mRev = new byte[message.Length]; // conversion is little-endian for (int i = 0; i != mRev.Length; i++) { mRev[i] = message[mRev.Length - 1 - i]; } BigInteger e = new BigInteger(1, mRev); BigInteger n = key.Parameters.N; // r in the range [1,n-1] if (r.CompareTo(BigInteger.One) < 0 || r.CompareTo(n) >= 0) { return false; } // s in the range [1,n-1] if (s.CompareTo(BigInteger.One) < 0 || s.CompareTo(n) >= 0) { return false; } BigInteger v = e.ModInverse(n); BigInteger z1 = s.Multiply(v).Mod(n); BigInteger z2 = (n.Subtract(r)).Multiply(v).Mod(n); ECPoint G = key.Parameters.G; // P ECPoint Q = ((ECPublicKeyParameters)key).Q; ECPoint point = ECAlgorithms.SumOfTwoMultiplies(G, z1, Q, z2).Normalize(); if (point.IsInfinity) return false; BigInteger R = point.AffineXCoord.ToBigInteger().Mod(n); return R.Equals(r); }