/**
* given a message from a given party and the coresponding public key
* calculate the next message in the agreement sequence. In this case
* this will represent the shared secret.
*/
public BigInteger calculateAgreement(
DHPublicKeyParameters pub,
BigInteger message)
{
if (!pub.getParameters().Equals(dhParams))
{
throw new ArgumentException("Diffie-Hellman public key has wrong parameters.");
}
return(message.modPow(key.getX(), dhParams.getP()).multiply(pub.getY().modPow(privateValue, dhParams.getP())).mod(dhParams.getP()));
}
/**
* given a short term public key from a given party calculate the next
* message in the agreement sequence.
*/
public BigInteger calculateAgreement(
CipherParameters pubKey)
{
DHPublicKeyParameters pub = (DHPublicKeyParameters)pubKey;
if (!pub.getParameters().Equals(dhParams))
{
throw new ArgumentException("Diffie-Hellman public key has wrong parameters.");
}
return(pub.getY().modPow(key.getX(), dhParams.getP()));
}
public static PrivateKeyInfo createPrivateKeyInfo(AsymmetricKeyParameter key)
{
/*
* Process DH private key.
* The value for L was set to zero implicitly.
* This is the same action as found in JCEDHPrivateKey getEncoded method.
*/
if (key is ElGamalPrivateKeyParameters)
{
ElGamalPrivateKeyParameters _key = (ElGamalPrivateKeyParameters)key;
PrivateKeyInfo info =
new PrivateKeyInfo(
new AlgorithmIdentifier(
OIWObjectIdentifiers.elGamalAlgorithm,
new ElGamalParameter(
_key.getParameters().getP(),
_key.getParameters().getG()).toASN1Object()), new DERInteger(_key.getX()));
return(info);
}
if (key is DSAPrivateKeyParameters)
{
DSAPrivateKeyParameters _key = (DSAPrivateKeyParameters)key;
PrivateKeyInfo info =
new PrivateKeyInfo(
new AlgorithmIdentifier(
X9ObjectIdentifiers.id_dsa,
new DSAParameter(
_key.getParameters().getP(),
_key.getParameters().getQ(),
_key.getParameters().getG()).toASN1Object()), new DERInteger(_key.getX()));
return(info);
}
if (key is DHPrivateKeyParameters)
{
DHPrivateKeyParameters _key = (DHPrivateKeyParameters)key;
PrivateKeyInfo info = new PrivateKeyInfo(
new AlgorithmIdentifier(
PKCSObjectIdentifiers.dhKeyAgreement, new DHParameter(
_key.getParameters().getP(),
_key.getParameters().getG(),
0
).toASN1Object()
)
, new DERInteger(_key.getX()));
return(info);
}
if (key is RSAPrivateCrtKeyParameters)
{
RSAPrivateCrtKeyParameters _key = (RSAPrivateCrtKeyParameters)key;
PrivateKeyInfo info = new PrivateKeyInfo(
new AlgorithmIdentifier(
PKCSObjectIdentifiers.rsaEncryption, new DERNull()),
new RSAPrivateKeyStructure(
_key.getModulus(),
_key.getPublicExponent(),
_key.getExponent(),
_key.getP(),
_key.getQ(),
_key.getDP(),
_key.getDQ(),
_key.getQInv()).toASN1Object());
return(info);
}
if (key is ECPrivateKeyParameters)
{
ECPrivateKeyParameters _key = (ECPrivateKeyParameters)key;
X9ECParameters ecP = new X9ECParameters(
_key.getParameters().getCurve(),
_key.getParameters().getG(),
_key.getParameters().getN(),
_key.getParameters().getH(),
_key.getParameters().getSeed());
X962Parameters x962 = new X962Parameters(ecP);
PrivateKeyInfo info = new PrivateKeyInfo(
new AlgorithmIdentifier(X9ObjectIdentifiers.id_ecPublicKey, x962.toASN1Object()),
new ECPrivateKeyStructure(_key.getD()).toASN1Object());
return(info);
}
throw (new Exception("Class provided is not convertable:" + key.GetType()));
}
