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127 lines
4.0 KiB
Java
127 lines
4.0 KiB
Java
/*
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* Copyright 2010-2012 sshj contributors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* This file may incorporate work covered by the following copyright and
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* permission notice:
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*
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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package net.schmizz.sshj.signature;
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import java.security.SignatureException;
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import net.schmizz.sshj.common.KeyType;
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import net.schmizz.sshj.common.SSHRuntimeException;
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/** DSA {@link Signature} */
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public class SignatureDSA
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extends AbstractSignature {
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/** A named factory for DSA signature */
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public static class Factory
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implements net.schmizz.sshj.common.Factory.Named<Signature> {
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@Override
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public Signature create() {
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return new SignatureDSA();
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}
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@Override
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public String getName() {
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return KeyType.DSA.toString();
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}
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}
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public SignatureDSA() {
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super("SHA1withDSA");
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}
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@Override
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public byte[] encode(byte[] sig) {
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// sig is in ASN.1
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// SEQUENCE::={ r INTEGER, s INTEGER }
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int rIndex = 3;
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int rLen = sig[rIndex++] & 0xff;
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byte[] r = new byte[rLen];
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System.arraycopy(sig, rIndex, r, 0, r.length);
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int sIndex = rIndex + rLen + 1;
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int sLen = sig[sIndex++] & 0xff;
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byte[] s = new byte[sLen];
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System.arraycopy(sig, sIndex, s, 0, s.length);
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byte[] result = new byte[40];
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// result must be 40 bytes, but length of r and s may not be 20 bytes
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int r_copylen = (r.length < 20) ? r.length : 20;
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int s_copylen = (s.length < 20) ? s.length : 20;
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System.arraycopy(r, r.length - r_copylen, result, 20 - r_copylen, r_copylen);
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System.arraycopy(s, s.length - s_copylen, result, 40 - s_copylen, s_copylen);
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return result;
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}
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@Override
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public boolean verify(byte[] sig) {
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sig = extractSig(sig);
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// ASN.1
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int frst = (sig[0] & 0x80) != 0 ? 1 : 0;
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int scnd = (sig[20] & 0x80) != 0 ? 1 : 0;
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int length = sig.length + 6 + frst + scnd;
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byte[] tmp = new byte[length];
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tmp[0] = (byte) 0x30;
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tmp[1] = (byte) 0x2c;
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tmp[1] += frst;
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tmp[1] += scnd;
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tmp[2] = (byte) 0x02;
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tmp[3] = (byte) 0x14;
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tmp[3] += frst;
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System.arraycopy(sig, 0, tmp, 4 + frst, 20);
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tmp[4 + tmp[3]] = (byte) 0x02;
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tmp[5 + tmp[3]] = (byte) 0x14;
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tmp[5 + tmp[3]] += scnd;
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System.arraycopy(sig, 20, tmp, 6 + tmp[3] + scnd, 20);
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sig = tmp;
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try {
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return signature.verify(sig);
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} catch (SignatureException e) {
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throw new SSHRuntimeException(e);
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}
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}
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}
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