package gnu.crypto.sig;
// ----------------------------------------------------------------------------
// $Id: BaseSignature.java,v 1.8 2005/10/06 04:24:18 rsdio Exp $
//
// Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc.
//
// This file is part of GNU Crypto.
//
// GNU Crypto is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
//
// GNU Crypto is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; see the file COPYING. If not, write to the
//
// Free Software Foundation Inc.,
// 51 Franklin Street, Fifth Floor,
// Boston, MA 02110-1301
// USA
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library. Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
//
// As a special exception, the copyright holders of this library give
// you permission to link this library with independent modules to
// produce an executable, regardless of the license terms of these
// independent modules, and to copy and distribute the resulting
// executable under terms of your choice, provided that you also meet,
// for each linked independent module, the terms and conditions of the
// license of that module. An independent module is a module which is
// not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the
// library, but you are not obligated to do so. If you do not wish to
// do so, delete this exception statement from your version.
// ----------------------------------------------------------------------------
import gnu.crypto.hash.IMessageDigest;
import gnu.crypto.prng.IRandom;
import gnu.crypto.prng.LimitReachedException;
import gnu.crypto.util.PRNG;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.util.Map;
import java.util.Random;
/**
* <p>A base abstract class to facilitate implementations of concrete
* Signatures.</p>
*
* @version $Revision: 1.8 $
*/
public abstract class BaseSignature implements ISignature {
// Constants and variables
// -------------------------------------------------------------------------
/** The canonical name of this signature scheme. */
protected String schemeName;
/** The underlying message digest instance for this signature scheme. */
protected IMessageDigest md;
/** The public key to use when verifying signatures. */
protected PublicKey publicKey;
/** The private key to use when generating signatures (signing). */
protected PrivateKey privateKey;
/** The optional {@link Random} instance to use. */
private Random rnd;
/** The optional {@link IRandom} instance to use. */
private IRandom irnd;
// Constructor(s)
// -------------------------------------------------------------------------
/**
* <p>Trivial constructor.</p>
*
* @param schemeName the name of this signature scheme.
* @param md the underlying instance of the message digest algorithm.
*/
protected BaseSignature(String schemeName, IMessageDigest md) {
super();
this.schemeName = schemeName;
this.md = md;
}
// Class methods
// -------------------------------------------------------------------------
// Instance methods
// -------------------------------------------------------------------------
// gnu.crypto.sig.ISignature interface implementation ----------------------
public String name() {
return schemeName;
}
public void setupVerify(Map attributes) throws IllegalArgumentException {
setup(attributes);
// do we have a public key?
PublicKey key = (PublicKey) attributes.get(VERIFIER_KEY);
if (key != null) {
setupForVerification(key);
}
}
public void setupSign(Map attributes) throws IllegalArgumentException {
setup(attributes);
// do we have a private key?
PrivateKey key = (PrivateKey) attributes.get(SIGNER_KEY);
if (key != null) {
setupForSigning(key);
}
}
public void update(byte b) {
if (md == null) {
throw new IllegalStateException();
}
md.update(b);
}
public void update(byte[] b, int off, int len) {
if (md == null) {
throw new IllegalStateException();
}
md.update(b, off, len);
}
public Object sign() {
if (md == null || privateKey == null) {
throw new IllegalStateException();
}
return generateSignature();
}
public boolean verify(Object sig) {
if (md == null || publicKey == null) {
throw new IllegalStateException();
}
return verifySignature(sig);
}
// abstract methods to be implemented by concrete subclasses ---------------
public abstract Object clone();
protected abstract void setupForVerification(PublicKey key)
throws IllegalArgumentException;
protected abstract void setupForSigning(PrivateKey key)
throws IllegalArgumentException;
protected abstract Object generateSignature()
throws IllegalStateException;
protected abstract boolean verifySignature(Object signature)
throws IllegalStateException;
// Other instance methods --------------------------------------------------
/** Initialises the internal fields of this instance. */
protected void init() {
md.reset();
rnd = null;
irnd = null;
publicKey = null;
privateKey = null;
}
/**
* <p>Fills the designated byte array with random data.</p>
*
* @param buffer the byte array to fill with random data.
*/
protected void nextRandomBytes(byte[] buffer) {
if (rnd != null) {
rnd.nextBytes(buffer);
} else if (irnd != null) {
try {
irnd.nextBytes(buffer, 0, buffer.length);
} catch (IllegalStateException x) {
throw new RuntimeException("nextRandomBytes(): "+String.valueOf(x));
} catch (LimitReachedException x) {
throw new RuntimeException("nextRandomBytes(): "+String.valueOf(x));
}
} else {
PRNG.nextBytes(buffer);
}
}
private void setup(Map attributes) {
init();
// do we have a Random or SecureRandom, or should we use our own?
Object obj = attributes.get(SOURCE_OF_RANDOMNESS);
if (obj instanceof Random) {
rnd = (Random) obj;
} else if (obj instanceof IRandom) {
irnd = (IRandom) obj;
}
}
}