/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.sshd.common.signature;
import java.math.BigInteger;
import java.security.PublicKey;
import java.security.interfaces.RSAKey;
import org.apache.sshd.common.keyprovider.KeyPairProvider;
import org.apache.sshd.common.util.Pair;
import org.apache.sshd.common.util.ValidateUtils;
/**
* RSA <code>Signature</code>
*
* @author <a href="mailto:dev@mina.apache.org">Apache MINA SSHD Project</a>
* @see <A HREF="https://tools.ietf.org/html/rfc4253#section-6.6">RFC4253 section 6.6</A>
*/
public class SignatureRSA extends AbstractSignature {
public static final String DEFAULT_ALGORITHM = "SHA1withRSA";
private int verifierSignatureSize = -1;
public SignatureRSA() {
super(DEFAULT_ALGORITHM);
}
protected SignatureRSA(String algorithm) {
super(algorithm);
}
/**
* @return The expected number of bytes in the signature - non-positive
* if not initialized or not intended to be used for verification
*/
protected int getVerifierSignatureSize() {
return verifierSignatureSize;
}
@Override
public void initVerifier(PublicKey key) throws Exception {
super.initVerifier(key);
RSAKey rsaKey = ValidateUtils.checkInstanceOf(key, RSAKey.class, "Not an RSA key");
verifierSignatureSize = getVerifierSignatureSize(rsaKey);
}
public static int getVerifierSignatureSize(RSAKey key) {
BigInteger modulus = key.getModulus();
return (modulus.bitLength() + Byte.SIZE - 1) / Byte.SIZE;
}
@Override
public boolean verify(byte[] sig) throws Exception {
byte[] data = sig;
Pair<String, byte[]> encoding = extractEncodedSignature(data);
if (encoding != null) {
String keyType = encoding.getFirst();
ValidateUtils.checkTrue(KeyPairProvider.SSH_RSA.equals(keyType), "Mismatched key type: %s", keyType);
data = encoding.getSecond();
}
int expectedSize = getVerifierSignatureSize();
ValidateUtils.checkTrue(expectedSize > 0, "Signature verification size has not been initialized");
// Pad with zero if value is trimmed
if (data.length < expectedSize) {
byte[] pad = new byte[expectedSize];
System.arraycopy(data, 0, pad, pad.length - data.length, data.length);
data = pad;
}
return doVerify(data);
}
}