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package org.spongycastle.openpgp.operator.bc;
import org.spongycastle.asn1.nist.NISTNamedCurves;
import org.spongycastle.asn1.x9.X9ECParameters;
import org.spongycastle.bcpg.ECDHPublicBCPGKey;
import org.spongycastle.bcpg.ECSecretBCPGKey;
import org.spongycastle.crypto.AsymmetricBlockCipher;
import org.spongycastle.crypto.BlockCipher;
import org.spongycastle.crypto.BufferedAsymmetricBlockCipher;
import org.spongycastle.crypto.InvalidCipherTextException;
import org.spongycastle.crypto.Wrapper;
import org.spongycastle.crypto.params.AsymmetricKeyParameter;
import org.spongycastle.crypto.params.ElGamalPrivateKeyParameters;
import org.spongycastle.crypto.params.KeyParameter;
import org.spongycastle.math.ec.ECPoint;
import org.spongycastle.openpgp.PGPException;
import org.spongycastle.openpgp.PGPPrivateKey;
import org.spongycastle.openpgp.PGPPublicKey;
import org.spongycastle.openpgp.operator.PGPDataDecryptor;
import org.spongycastle.openpgp.operator.PGPPad;
import org.spongycastle.openpgp.operator.PublicKeyDataDecryptorFactory;
import org.spongycastle.openpgp.operator.RFC6637KDFCalculator;
/**
* A decryptor factory for handling public key decryption operations.
*/
public class BcPublicKeyDataDecryptorFactory
implements PublicKeyDataDecryptorFactory
{
private BcPGPKeyConverter keyConverter = new BcPGPKeyConverter();
private PGPPrivateKey privKey;
public BcPublicKeyDataDecryptorFactory(PGPPrivateKey privKey)
{
this.privKey = privKey;
}
public byte[] recoverSessionData(int keyAlgorithm, byte[][] secKeyData)
throws PGPException
{
try
{
if (keyAlgorithm != PGPPublicKey.ECDH)
{
AsymmetricBlockCipher c = BcImplProvider.createPublicKeyCipher(keyAlgorithm);
AsymmetricKeyParameter key = keyConverter.getPrivateKey(privKey);
BufferedAsymmetricBlockCipher c1 = new BufferedAsymmetricBlockCipher(c);
c1.init(false, key);
if (keyAlgorithm == PGPPublicKey.RSA_ENCRYPT
|| keyAlgorithm == PGPPublicKey.RSA_GENERAL)
{
byte[] bi = secKeyData[0];
c1.processBytes(bi, 2, bi.length - 2);
}
else
{
BcPGPKeyConverter converter = new BcPGPKeyConverter();
ElGamalPrivateKeyParameters parms = (ElGamalPrivateKeyParameters)converter.getPrivateKey(privKey);
int size = (parms.getParameters().getP().bitLength() + 7) / 8;
byte[] tmp = new byte[size];
byte[] bi = secKeyData[0]; // encoded MPI
if (bi.length - 2 > size) // leading Zero? Shouldn't happen but...
{
c1.processBytes(bi, 3, bi.length - 3);
}
else
{
System.arraycopy(bi, 2, tmp, tmp.length - (bi.length - 2), bi.length - 2);
c1.processBytes(tmp, 0, tmp.length);
}
bi = secKeyData[1]; // encoded MPI
for (int i = 0; i != tmp.length; i++)
{
tmp[i] = 0;
}
if (bi.length - 2 > size) // leading Zero? Shouldn't happen but...
{
c1.processBytes(bi, 3, bi.length - 3);
}
else
{
System.arraycopy(bi, 2, tmp, tmp.length - (bi.length - 2), bi.length - 2);
c1.processBytes(tmp, 0, tmp.length);
}
}
return c1.doFinal();
}
else
{
ECDHPublicBCPGKey ecKey = (ECDHPublicBCPGKey)privKey.getPublicKeyPacket().getKey();
X9ECParameters x9Params = NISTNamedCurves.getByOID(ecKey.getCurveOID());
byte[] enc = secKeyData[0];
int pLen = ((((enc[0] & 0xff) << 8) + (enc[1] & 0xff)) + 7) / 8;
byte[] pEnc = new byte[pLen];
System.arraycopy(enc, 2, pEnc, 0, pLen);
byte[] keyEnc = new byte[enc[pLen + 2]];
System.arraycopy(enc, 2 + pLen + 1, keyEnc, 0, keyEnc.length);
Wrapper c = BcImplProvider.createWrapper(ecKey.getSymmetricKeyAlgorithm());
ECPoint S = x9Params.getCurve().decodePoint(pEnc).multiply(((ECSecretBCPGKey)privKey.getPrivateKeyDataPacket()).getX()).normalize();
RFC6637KDFCalculator rfc6637KDFCalculator = new RFC6637KDFCalculator(new BcPGPDigestCalculatorProvider().get(ecKey.getHashAlgorithm()), ecKey.getSymmetricKeyAlgorithm());
KeyParameter key = new KeyParameter(rfc6637KDFCalculator.createKey(ecKey.getCurveOID(), S, new BcKeyFingerprintCalculator().calculateFingerprint(privKey.getPublicKeyPacket())));
c.init(false, key);
return PGPPad.unpadSessionData(c.unwrap(keyEnc, 0, keyEnc.length));
}
}
catch (InvalidCipherTextException e)
{
throw new PGPException("exception encrypting session info: " + e.getMessage(), e);
}
}
public PGPDataDecryptor createDataDecryptor(boolean withIntegrityPacket, int encAlgorithm, byte[] key)
throws PGPException
{
BlockCipher engine = BcImplProvider.createBlockCipher(encAlgorithm);
return BcUtil.createDataDecryptor(withIntegrityPacket, engine, key);
}
}
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