Java tutorial
/* * SSHTools - Java SSH2 API * * Copyright (C) 2002 Lee David Painter. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU Library General Public License * as published by the Free Software Foundation; either version 2 of * the License, or (at your option) any later version. * * You may also distribute it and/or modify it under the terms of the * Apache style J2SSH Software License. A copy of which should have * been provided with the distribution. * * This program 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 * License document supplied with your distribution for more details. * */ package com.sshtools.j2ssh.transport.publickey.dsa; import java.io.IOException; import java.math.BigInteger; import java.security.KeyFactory; import java.security.Signature; import java.security.interfaces.DSAPrivateKey; import java.security.interfaces.DSAPublicKey; import java.security.spec.DSAPrivateKeySpec; import java.security.spec.DSAPublicKeySpec; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import com.sshtools.j2ssh.io.ByteArrayReader; import com.sshtools.j2ssh.io.ByteArrayWriter; import com.sshtools.j2ssh.transport.publickey.InvalidSshKeyException; import com.sshtools.j2ssh.transport.publickey.InvalidSshKeySignatureException; import com.sshtools.j2ssh.transport.publickey.SshPrivateKey; import com.sshtools.j2ssh.transport.publickey.SshPublicKey; import com.sshtools.j2ssh.util.SimpleASNReader; class SshDssPrivateKey extends SshPrivateKey { private static Log log = LogFactory.getLog(SshDssPrivateKey.class); DSAPrivateKey prvkey; /** * Creates a new SshDssPrivateKey object. * * @param prvkey */ public SshDssPrivateKey(DSAPrivateKey prvkey) { this.prvkey = prvkey; } /** * Creates a new SshDssPrivateKey object. * * @param key * * @throws InvalidSshKeyException */ public SshDssPrivateKey(byte[] key) throws InvalidSshKeyException { try { DSAPrivateKeySpec dsaKey; // Extract the key information ByteArrayReader bar = new ByteArrayReader(key); String header = bar.readString(); if (!header.equals(getAlgorithmName())) { throw new InvalidSshKeyException(); } BigInteger p = bar.readBigInteger(); BigInteger q = bar.readBigInteger(); BigInteger g = bar.readBigInteger(); BigInteger x = bar.readBigInteger(); dsaKey = new DSAPrivateKeySpec(x, p, q, g); KeyFactory kf = KeyFactory.getInstance("DSA"); prvkey = (DSAPrivateKey) kf.generatePrivate(dsaKey); log.info(prvkey.getParams().getP().toString(16)); log.info(prvkey.getParams().getQ().toString(16)); log.info(prvkey.getParams().getG().toString(16)); log.info(getY().toString(16)); } catch (Exception e) { throw new InvalidSshKeyException(); } } /** * * * @param obj * * @return */ public boolean equals(Object obj) { if (obj instanceof SshDssPrivateKey) { return prvkey.equals(((SshDssPrivateKey) obj).prvkey); } return false; } /** * * * @return */ public int hashCode() { return prvkey.hashCode(); } /** * * * @return */ public String getAlgorithmName() { return "ssh-dss"; } /** * * * @return */ public int getBitLength() { return prvkey.getX().bitLength(); } /** * * * @return */ public byte[] getEncoded() { try { ByteArrayWriter baw = new ByteArrayWriter(); baw.writeString("ssh-dss"); baw.writeBigInteger(prvkey.getParams().getP()); baw.writeBigInteger(prvkey.getParams().getQ()); baw.writeBigInteger(prvkey.getParams().getG()); baw.writeBigInteger(prvkey.getX()); return baw.toByteArray(); } catch (IOException ioe) { return null; } } /** * * * @return */ public SshPublicKey getPublicKey() { try { DSAPublicKeySpec spec = new DSAPublicKeySpec(getY(), prvkey.getParams().getP(), prvkey.getParams().getQ(), prvkey.getParams().getG()); KeyFactory kf = KeyFactory.getInstance("DSA"); return new SshDssPublicKey((DSAPublicKey) kf.generatePublic(spec)); } catch (Exception e) { return null; } } /** * * * @param data * * @return * * @throws InvalidSshKeySignatureException */ public byte[] generateSignature(byte[] data) throws InvalidSshKeySignatureException { try { Signature sig = Signature.getInstance("SHA1withDSA"); sig.initSign(prvkey); /*java.util.Random rnd = new java.util.Random(); byte[] buffer = new byte[20]; rnd.nextBytes(buffer); sig.update(buffer); byte[] test = sig.sign();*/ sig.update(data); byte[] signature = sig.sign(); byte[] decoded = new byte[40]; SimpleASNReader asn = new SimpleASNReader(signature); asn.getByte(); asn.getLength(); asn.getByte(); byte[] r = asn.getData(); asn.getByte(); byte[] s = asn.getData(); if (r.length >= 20) { System.arraycopy(r, r.length - 20, decoded, 0, 20); } else { System.arraycopy(r, 0, decoded, 20 - r.length, r.length); } if (s.length >= 20) { System.arraycopy(s, s.length - 20, decoded, 20, 20); } else { System.arraycopy(s, 0, decoded, 20 + (20 - s.length), s.length); } if (log.isDebugEnabled()) { BigInteger rb = new BigInteger(1, r); log.debug(rb.toString(16)); BigInteger sb = new BigInteger(1, s); log.debug(sb.toString(16)); log.debug("s length is " + String.valueOf(s.length)); log.debug("r length is " + String.valueOf(r.length)); String str = ""; for (int i = 0; i < signature.length; i++) { str += (Integer.toHexString(signature[i] & 0xFF) + " "); } log.debug("Java signature is " + str); str = ""; for (int i = 0; i < decoded.length; i++) { str += (Integer.toHexString(decoded[i] & 0xFF) + " "); } log.debug("SSH signature is " + str); } ByteArrayWriter baw = new ByteArrayWriter(); baw.writeString(getAlgorithmName()); baw.writeBinaryString(decoded); return baw.toByteArray(); } catch (Exception e) { throw new InvalidSshKeySignatureException(e); } } private BigInteger getY() { return prvkey.getParams().getG().modPow(prvkey.getX(), prvkey.getParams().getP()); } }