package gnu.crypto.sig.dss;
// ----------------------------------------------------------------------------
// $Id: DSSSignatureRawCodec.java,v 1.5 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
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// for each linked independent module, the terms and conditions of the
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// 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.Registry;
import gnu.crypto.sig.ISignatureCodec;
import java.io.ByteArrayOutputStream;
import java.math.BigInteger;
/**
* <p>An object that implements the {@link ISignatureCodec} operations for the
* <i>Raw</i> format to use with DSS signatures.</p>
*
* @version $Revision: 1.5 $
*/
public class DSSSignatureRawCodec implements ISignatureCodec {
// Constants and variables
// -------------------------------------------------------------------------
// Constructor(s)
// -------------------------------------------------------------------------
// implicit 0-arguments constructor
// Class methods
// -------------------------------------------------------------------------
// Instance methods
// -------------------------------------------------------------------------
// gnu.crypto.sig.ISignatureCodec interface implementation -----------------
public int getFormatID() {
return RAW_FORMAT;
}
/**
* <p>Returns the encoded form of the designated DSS (Digital Signature
* Standard) signature object according to the <i>Raw</i> format supported by
* this library.</p>
*
* <p>The <i>Raw</i> format for a DSA signature, in this implementation, is a
* byte sequence consisting of the following:</p>
*
* <ol>
* <li>4-byte magic consisting of the value of the literal
* {@link Registry#MAGIC_RAW_DSS_SIGNATURE},</li>
* <li>1-byte version consisting of the constant: 0x01,</li>
* <li>4-byte count of following bytes representing the DSS parameter
* <code>r</code> in internet order,</li>
* <li>n-bytes representation of a {@link BigInteger} obtained by invoking
* the <code>toByteArray()</code> method on the DSS parameter <code>r</code>,</li>
* <li>4-byte count of following bytes representing the DSS parameter
* <code>s</code>,</li>
* <li>n-bytes representation of a {@link BigInteger} obtained by invoking
* the <code>toByteArray()</code> method on the DSS parameter <code>s</code>.</li>
* </ol>
*
* @param signature the signature to encode, consisting of the two DSS
* parameters <code>r</code> and <code>s</code> as a {@link java.math.BigInteger}
* array.
* @return the <i>Raw</i> format encoding of the designated signature.
* @exception IllegalArgumentException if the designated signature is not a
* DSS (Digital Signature Standard) one.
*/
public byte[] encodeSignature(Object signature) {
BigInteger r, s;
try {
BigInteger[] sig = (BigInteger[]) signature;
r = sig[0];
s = sig[1];
} catch (Exception x) {
throw new IllegalArgumentException("key");
}
ByteArrayOutputStream baos = new ByteArrayOutputStream();
// magic
baos.write(Registry.MAGIC_RAW_DSS_SIGNATURE[0]);
baos.write(Registry.MAGIC_RAW_DSS_SIGNATURE[1]);
baos.write(Registry.MAGIC_RAW_DSS_SIGNATURE[2]);
baos.write(Registry.MAGIC_RAW_DSS_SIGNATURE[3]);
// version
baos.write(0x01);
// r
byte[] buffer = r.toByteArray();
int length = buffer.length;
baos.write( length >>> 24 );
baos.write((length >>> 16) & 0xFF);
baos.write((length >>> 8) & 0xFF);
baos.write( length & 0xFF);
baos.write(buffer, 0, length);
// s
buffer = s.toByteArray();
length = buffer.length;
baos.write( length >>> 24 );
baos.write((length >>> 16) & 0xFF);
baos.write((length >>> 8) & 0xFF);
baos.write( length & 0xFF);
baos.write(buffer, 0, length);
return baos.toByteArray();
}
public Object decodeSignature(byte[] k) {
// magic
if (k[0] != Registry.MAGIC_RAW_DSS_SIGNATURE[0]
|| k[1] != Registry.MAGIC_RAW_DSS_SIGNATURE[1]
|| k[2] != Registry.MAGIC_RAW_DSS_SIGNATURE[2]
|| k[3] != Registry.MAGIC_RAW_DSS_SIGNATURE[3]) {
throw new IllegalArgumentException("magic");
}
// version
if (k[4] != 0x01) {
throw new IllegalArgumentException("version");
}
int i = 5;
int l;
byte[] buffer;
// r
l = k[i++] << 24 | (k[i++] & 0xFF) << 16 | (k[i++] & 0xFF) << 8 | (k[i++] & 0xFF);
buffer = new byte[l];
System.arraycopy(k, i, buffer, 0, l);
i += l;
BigInteger r = new BigInteger(1, buffer);
// s
l = k[i++] << 24 | (k[i++] & 0xFF) << 16 | (k[i++] & 0xFF) << 8 | (k[i++] & 0xFF);
buffer = new byte[l];
System.arraycopy(k, i, buffer, 0, l);
i += l;
BigInteger s = new BigInteger(1, buffer);
return new BigInteger[] {r, s};
}
}