ECMqvBasicAgreement
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Math.EC;
using System;
namespace Org.BouncyCastle.Crypto.Agreement
{
public class ECMqvBasicAgreement : IBasicAgreement
{
protected internal MqvPrivateParameters privParams;
public virtual void Init(ICipherParameters parameters)
{
ParametersWithRandom parametersWithRandom = parameters as ParametersWithRandom;
if (parametersWithRandom != null)
parameters = parametersWithRandom.Parameters;
MqvPrivateParameters mqvPrivateParameters = parameters as MqvPrivateParameters;
if (mqvPrivateParameters == null)
throw new ArgumentException("ECMqvBasicAgreement expects MqvPrivateParameters");
privParams = mqvPrivateParameters;
}
public virtual int GetFieldSize()
{
return privParams.StaticPrivateKey.Parameters.Curve.FieldElementEncodingLength;
}
public virtual BigInteger CalculateAgreement(ICipherParameters pubKey)
{
MqvPublicParameters mqvPublicParameters = (MqvPublicParameters)pubKey;
ECPrivateKeyParameters staticPrivateKey = privParams.StaticPrivateKey;
ECDomainParameters parameters = staticPrivateKey.Parameters;
if (!parameters.Equals(mqvPublicParameters.StaticPublicKey.Parameters))
throw new InvalidOperationException("ECMQV public key components have wrong domain parameters");
ECPoint eCPoint = CalculateMqvAgreement(parameters, staticPrivateKey, privParams.EphemeralPrivateKey, privParams.EphemeralPublicKey, mqvPublicParameters.StaticPublicKey, mqvPublicParameters.EphemeralPublicKey).Normalize();
if (eCPoint.IsInfinity)
throw new InvalidOperationException("Infinity is not a valid agreement value for MQV");
return eCPoint.AffineXCoord.ToBigInteger();
}
private static ECPoint CalculateMqvAgreement(ECDomainParameters parameters, ECPrivateKeyParameters d1U, ECPrivateKeyParameters d2U, ECPublicKeyParameters Q2U, ECPublicKeyParameters Q1V, ECPublicKeyParameters Q2V)
{
BigInteger n = parameters.N;
int num = (n.BitLength + 1) / 2;
BigInteger m = BigInteger.One.ShiftLeft(num);
ECCurve curve = parameters.Curve;
ECPoint eCPoint = ECAlgorithms.CleanPoint(curve, Q2U.Q);
ECPoint p = ECAlgorithms.CleanPoint(curve, Q1V.Q);
ECPoint eCPoint2 = ECAlgorithms.CleanPoint(curve, Q2V.Q);
BigInteger val = eCPoint.AffineXCoord.ToBigInteger().Mod(m).SetBit(num);
BigInteger val2 = d1U.D.Multiply(val).Add(d2U.D).Mod(n);
BigInteger bigInteger = eCPoint2.AffineXCoord.ToBigInteger().Mod(m).SetBit(num);
BigInteger bigInteger2 = parameters.H.Multiply(val2).Mod(n);
return ECAlgorithms.SumOfTwoMultiplies(p, bigInteger.Multiply(bigInteger2).Mod(n), eCPoint2, bigInteger2);
}
}
}