/// <summary>
/// Create a Subject Public Key Info object for a given public key.
/// </summary>
/// <param name="key">One of ElGammalPublicKeyParameters, DSAPublicKeyParameter, DHPublicKeyParameters, RSAKeyParameters or ECPublicKeyParameters</param>
/// <returns>A subject public key info object.</returns>
/// <exception cref="Exception">Throw exception if object provided is not one of the above.</exception>
public static SubjectPublicKeyInfo CreateSubjectPublicKeyInfo(AsymmetricKeyParameter key)
{
if (key.isPrivate())
{
throw (new Exception("Private key passed - public key expected."));
}
if (key is ElGamalPublicKeyParameters)
{
ElGamalPublicKeyParameters _key = (ElGamalPublicKeyParameters)key;
SubjectPublicKeyInfo info =
new SubjectPublicKeyInfo(
new AlgorithmIdentifier(
OIWObjectIdentifiers.elGamalAlgorithm,
new ElGamalParameter(
_key.getParameters().getP(),
_key.getParameters().getG()
).toASN1Object()), new DERInteger(_key.getY()));
return(info);
}
if (key is DSAPublicKeyParameters)
{
DSAPublicKeyParameters _key = (DSAPublicKeyParameters)key;
SubjectPublicKeyInfo info =
new SubjectPublicKeyInfo(
new AlgorithmIdentifier(
X9ObjectIdentifiers.id_dsa,
new DSAParameter(_key.getParameters().getP(), _key.getParameters().getQ(), _key.getParameters().getG()).toASN1Object()),
new DERInteger(_key.getY())
);
return(info);
}
if (key is DHPublicKeyParameters)
{
DHPublicKeyParameters _key = (DHPublicKeyParameters)key;
SubjectPublicKeyInfo info = new SubjectPublicKeyInfo(
new AlgorithmIdentifier(X9ObjectIdentifiers.dhpublicnumber,
new DHParameter(_key.getParameters().getP(),
_key.getParameters().getG(),
_key.getParameters().getJ()).toASN1Object()), new DERInteger(_key.getY()));
return(info);
} // End of DH
if (key is RSAKeyParameters)
{
RSAKeyParameters _key = (RSAKeyParameters)key;
if (_key.isPrivate())
{
throw (new Exception("Private RSA Key provided."));
}
SubjectPublicKeyInfo info = new SubjectPublicKeyInfo(new AlgorithmIdentifier(PKCSObjectIdentifiers.rsaEncryption, new DERNull()), new RSAPublicKeyStructure(_key.getModulus(), _key.getExponent()).toASN1Object());
return(info);
} // End of RSA.
if (key is ECPublicKeyParameters)
{
ECPublicKeyParameters _key = (ECPublicKeyParameters)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);
ASN1OctetString p = (ASN1OctetString)(new X9ECPoint(_key.getQ()).toASN1Object());
SubjectPublicKeyInfo info = new SubjectPublicKeyInfo(new AlgorithmIdentifier(X9ObjectIdentifiers.id_ecPublicKey, x962.toASN1Object()), p.getOctets());
return(info);
} // End of EC
throw (new Exception("Class provided no convertable:" + key.GetType()));
}
/**
* Process a single block using the basic RSA algorithm.
*
* @param in the input array.
* @param inOff the offset into the input buffer where the data starts.
* @param inLen the length of the data to be processed.
* @return the result of the RSA process.
* @exception DataLengthException the input block is too large.
*/
public byte[] processBlock(
byte[] inBytes,
int inOff,
int inLen)
{
if (inLen > (getInputBlockSize() + 1))
{
throw new DataLengthException("input too large for RSA cipher.\n");
}
else if (inLen == (getInputBlockSize() + 1) && (inBytes[inOff] & 0x80) != 0)
{
throw new DataLengthException("input too large for RSA cipher.\n");
}
byte[] block;
if (inOff != 0 || inLen != inBytes.Length)
{
block = new byte[inLen];
Array.Copy(inBytes, inOff, block, 0, inLen);
}
else
{
block = inBytes;
}
BigInteger input = new BigInteger(1, block);
byte[] output;
if (typeof(RSAPrivateCrtKeyParameters).IsInstanceOfType(key))
{
//
// we have the extra factors, use the Chinese Remainder Theorem - the author
// wishes to express his thanks to Dirk Bonekaemper at rtsffm.com for
// advice regarding the expression of this.
//
RSAPrivateCrtKeyParameters crtKey = (RSAPrivateCrtKeyParameters)key;
BigInteger p = crtKey.getP();
BigInteger q = crtKey.getQ();
BigInteger dP = crtKey.getDP();
BigInteger dQ = crtKey.getDQ();
BigInteger qInv = crtKey.getQInv();
BigInteger mP, mQ, h, m;
// mP = ((input mod p) ^ dP)) mod p
mP = (input.remainder(p)).modPow(dP, p);
// mQ = ((input mod q) ^ dQ)) mod q
mQ = (input.remainder(q)).modPow(dQ, q);
// h = qInv * (mP - mQ) mod p
h = mP.subtract(mQ);
h = h.multiply(qInv);
h = h.mod(p); // mod (in Java) returns the positive residual
// m = h * q + mQ
m = h.multiply(q);
m = m.add(mQ);
output = m.toByteArray();
}
else
{
output = input.modPow(
key.getExponent(), key.getModulus()).toByteArray();
}
if (forEncryption)
{
if (output[0] == 0 && output.Length > getOutputBlockSize()) // have ended up with an extra zero byte, copy down.
{
byte[] tmp = new byte[output.Length - 1];
Array.Copy(output, 1, tmp, 0, tmp.Length);
return(tmp);
}
if (output.Length < getOutputBlockSize()) // have ended up with less bytes than normal, lengthen
{
byte[] tmp = new byte[getOutputBlockSize()];
Array.Copy(output, 0, tmp, tmp.Length - output.Length, output.Length);
return(tmp);
}
}
else
{
if (output[0] == 0) // have ended up with an extra zero byte, copy down.
{
byte[] tmp = new byte[output.Length - 1];
Array.Copy(output, 1, tmp, 0, tmp.Length);
return(tmp);
}
}
return(output);
}
