/*
* Copyright (c) 2010-2011 Michael Laudati, N1 Concepts LLC.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* 3. The names of the authors may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL N1
* CONCEPTS, INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.vngx.jsch.algorithm;
import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.spec.DSAPrivateKeySpec;
import java.security.spec.DSAPublicKeySpec;
import org.vngx.jsch.Buffer;
/**
* Implementation of <code>SignatureDSA</code>.
*
* @author Michael Laudati
*/
public final class SignatureDSAImpl implements SignatureDSA {
/** Java JCE signature for signing using DSA encryption. */
private final Signature _signature;
/** Java JCE key factory. */
private final KeyFactory _keyFactory;
public SignatureDSAImpl() throws NoSuchAlgorithmException {
_signature = Signature.getInstance("SHA1withDSA");
_keyFactory = KeyFactory.getInstance("DSA");
}
@Override
public void setPubKey(byte[] y, byte[] p, byte[] q, byte[] g) throws Exception {
DSAPublicKeySpec dsaPubKeySpec = new DSAPublicKeySpec(new BigInteger(y), new BigInteger(p), new BigInteger(q), new BigInteger(g));
PublicKey pubKey = _keyFactory.generatePublic(dsaPubKeySpec);
_signature.initVerify(pubKey);
}
@Override
public void setPrvKey(byte[] x, byte[] p, byte[] q, byte[] g) throws Exception {
DSAPrivateKeySpec dsaPrivKeySpec = new DSAPrivateKeySpec(new BigInteger(x), new BigInteger(p), new BigInteger(q), new BigInteger(g));
PrivateKey prvKey = _keyFactory.generatePrivate(dsaPrivKeySpec);
_signature.initSign(prvKey);
}
@Override
public byte[] sign() throws Exception {
Buffer signature = new Buffer(_signature.sign());
// signature is in ASN.1
// SEQUENCE::={ r INTEGER, offset INTEGER }
signature.setOffSet(3); // skip DER-sequence type, seq length and DER bytearray type (1 byte each)
byte[] r = signature.getBytes(new byte[signature.getByte()]);
signature.getByte(); // skip DER bytearray type
byte[] s = signature.getBytes(new byte[signature.getByte()]);
// result must be 40 bytes, but length of r and offset may not be 20 bytes
byte[] result = new byte[40];
System.arraycopy(r, (r.length > 20) ? 1 : 0,
result, (r.length > 20) ? 0 : 20 - r.length,
(r.length > 20) ? 20 : r.length);
System.arraycopy(s, (s.length > 20) ? 1 : 0,
result, (s.length > 20) ? 20 : 40 - s.length,
(s.length > 20) ? 20 : s.length);
return result;
}
@Override
public void update(byte[] data) throws Exception {
_signature.update(data);
}
@Override
public boolean verify(byte[] signature) throws Exception {
if( (signature[0] | signature[1] | signature[2]) == 0 ) {
Buffer sigBuffer = new Buffer(signature);
sigBuffer.getString(); // Skip first string
signature = sigBuffer.getString(); // second is signature
}
// ASN.1
int frst = (signature[0] & 0x80) != 0 ? 1 : 0;
int scnd = (signature[20] & 0x80) != 0 ? 1 : 0;
byte[] tmp = new byte[signature.length + 6 + frst + scnd];
tmp[0] = (byte) 0x30;
tmp[1] = (byte) ((byte) 0x2c + (byte) frst + (byte) scnd);
tmp[2] = (byte) 0x02;
tmp[3] = (byte) ((byte) 0x14 + (byte) frst);
System.arraycopy(signature, 0, tmp, 4 + frst, 20);
tmp[4 + tmp[3]] = (byte) 0x02;
tmp[5 + tmp[3]] = (byte) ((byte) 0x14 + (byte) scnd);
System.arraycopy(signature, 20, tmp, 6 + tmp[3] + scnd, 20);
signature = tmp;
return _signature.verify(signature);
}
}