package gnu.java.security.provider;
import java.math.BigInteger;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.InvalidParameterException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.SignatureException;
import java.security.SignatureSpi;
import java.security.interfaces.DSAPrivateKey;
import java.security.interfaces.DSAPublicKey;
import java.security.spec.AlgorithmParameterSpec;
import java.util.Random;
import gnu.java.security.der.DEREncodingException;
public class DSASignature extends SignatureSpi
{
private DSAPublicKey publicKey;
private DSAPrivateKey privateKey;
private MessageDigest digest = null;
public DSASignature()
{}
private void init()
{
if( digest == null ) {
try {
digest = MessageDigest.getInstance( "SHA1", "GNU" );
} catch ( NoSuchAlgorithmException nsae ) {
digest = null;
} catch ( NoSuchProviderException nspe ) {
digest = null;
}
}
digest.reset();
}
public void engineInitVerify(PublicKey publicKey)
throws InvalidKeyException
{
if( publicKey instanceof DSAPublicKey )
this.publicKey = (DSAPublicKey)publicKey;
else
throw new InvalidKeyException();
init();
}
public void engineInitSign(PrivateKey privateKey)
throws InvalidKeyException
{
if( privateKey instanceof DSAPrivateKey )
this.privateKey = (DSAPrivateKey)privateKey;
else
throw new InvalidKeyException();
init();
}
public void engineInitSign(PrivateKey privateKey,
SecureRandom random)
throws InvalidKeyException
{
if( privateKey instanceof DSAPrivateKey )
this.privateKey = (DSAPrivateKey)privateKey;
else
throw new InvalidKeyException();
appRandom = random;
init();
}
public void engineUpdate(byte b)
throws SignatureException
{
if( digest == null )
throw new SignatureException();
digest.update( b );
}
public void engineUpdate(byte[] b, int off, int len)
throws SignatureException
{
if( digest == null )
throw new SignatureException();
digest.update( b, off, len );
}
public byte[] engineSign()
throws SignatureException
{
if( digest == null )
throw new SignatureException();
if( privateKey == null)
throw new SignatureException();
try {
BigInteger g = privateKey.getParams().getG();
BigInteger p = privateKey.getParams().getP();
BigInteger q = privateKey.getParams().getQ();
BigInteger x = privateKey.getX();
BigInteger k = new BigInteger( 159, (Random)appRandom );
BigInteger r = g.modPow(k, p);
r = r.mod(q);
byte bytes[] = digest.digest();
BigInteger sha = new BigInteger(1, bytes);
BigInteger s = sha.add( x.multiply( r ) );
s = s.multiply( k.modInverse(q) ).mod( q );
DERWriter writer = new DERWriter();
return writer.joinarrays( writer.writeBigInteger( r ), writer.writeBigInteger( s ) );
} catch ( ArithmeticException ae ) {
throw new SignatureException();
}
}
public int engineSign(byte[] outbuf, int offset, int len)
throws SignatureException
{
byte tmp[] = engineSign();
if( tmp.length > len )
throw new SignatureException();
System.arraycopy( tmp, 0, outbuf, offset, tmp.length );
return tmp.length;
}
public boolean engineVerify(byte[] sigBytes)
throws SignatureException
{
try {
DERReader reader = new DERReader( sigBytes );
BigInteger r = reader.getBigInteger();
BigInteger s = reader.getBigInteger();
BigInteger g = publicKey.getParams().getG();
BigInteger p = publicKey.getParams().getP();
BigInteger q = publicKey.getParams().getQ();
BigInteger y = publicKey.getY();
BigInteger w = s.modInverse( q );
byte bytes[] = digest.digest();
BigInteger sha = new BigInteger(1, bytes);
BigInteger u1 = w.multiply( sha ).mod( q );
BigInteger u2 = r.multiply( w ).mod( q );
BigInteger v = g.modPow( u1, p ).multiply( y.modPow( u2, p ) ).mod( p ).mod( q );
if( v.equals( r ) )
return true;
else
return false;
} catch ( DEREncodingException deree ) {
throw new SignatureException();
}
}
public void engineSetParameter(String param,
Object value)
throws InvalidParameterException
{
throw new InvalidParameterException();
}
public void engineSetParameter(AlgorithmParameterSpec params)
throws InvalidAlgorithmParameterException
{
throw new InvalidParameterException();
}
public Object engineGetParameter(String param)
throws InvalidParameterException
{
throw new InvalidParameterException();
}
public Object clone()
{
return new DSASignature( this );
}
private DSASignature( DSASignature copy )
{
this();
this.publicKey = copy.publicKey;
this.privateKey = copy.privateKey;
this.digest = copy.digest;
}
}