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using System;
using Org.BouncyCastle.Asn1.CryptoPro;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Security;
namespace Org.BouncyCastle.Crypto.Generators
{
/**
* a GOST3410 key pair generator.
* This generates GOST3410 keys in line with the method described
* in GOST R 34.10-94.
*/
public class Gost3410KeyPairGenerator
: IAsymmetricCipherKeyPairGenerator
{
private Gost3410KeyGenerationParameters param;
public void Init(
KeyGenerationParameters parameters)
{
if (parameters is Gost3410KeyGenerationParameters)
{
this.param = (Gost3410KeyGenerationParameters) parameters;
}
else
{
Gost3410KeyGenerationParameters kgp = new Gost3410KeyGenerationParameters(
parameters.Random,
CryptoProObjectIdentifiers.GostR3410x94CryptoProA);
if (parameters.Strength != kgp.Parameters.P.BitLength - 1)
{
// TODO Should we complain?
}
this.param = kgp;
}
}
public AsymmetricCipherKeyPair GenerateKeyPair()
{
SecureRandom random = param.Random;
Gost3410Parameters gost3410Params = param.Parameters;
BigInteger q = gost3410Params.Q;
BigInteger x;
do
{
x = new BigInteger(256, random);
}
while (x.SignValue < 1 || x.CompareTo(q) >= 0);
BigInteger p = gost3410Params.P;
BigInteger a = gost3410Params.A;
// calculate the public key.
BigInteger y = a.ModPow(x, p);
if (param.PublicKeyParamSet != null)
{
return new AsymmetricCipherKeyPair(
new Gost3410PublicKeyParameters(y, param.PublicKeyParamSet),
new Gost3410PrivateKeyParameters(x, param.PublicKeyParamSet));
}
return new AsymmetricCipherKeyPair(
new Gost3410PublicKeyParameters(y, gost3410Params),
new Gost3410PrivateKeyParameters(x, gost3410Params));
}
}
}
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