org.apache.sshd.common.mac.Mac Maven / Gradle / Ivy
/*
* 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.mac;
import org.apache.sshd.common.util.NumberUtils;
/**
* Message Authentication Code for use in SSH. It usually wraps a javax.crypto.Mac class.
*
* @author Apache MINA SSHD Project
*/
public interface Mac extends MacInformation {
void init(byte[] key) throws Exception;
default void update(byte[] buf) {
update(buf, 0, NumberUtils.length(buf));
}
void update(byte[] buf, int start, int len);
void updateUInt(long foo);
default byte[] doFinal() throws Exception {
int blockSize = getBlockSize();
byte[] buf = new byte[blockSize];
doFinal(buf);
return buf;
}
default void doFinal(byte[] buf) throws Exception {
doFinal(buf, 0);
}
void doFinal(byte[] buf, int offset) throws Exception;
/*
* Executes a more-or-less constant time verification in order
* to avoid timing side-channel information leak
*/
static boolean equals(byte[] a1, int a1Offset, byte[] a2, int a2Offset, int length) {
int len1 = NumberUtils.length(a1);
int len2 = NumberUtils.length(a2);
int result = 0;
if (len1 < (a1Offset + length)) {
length = Math.min(length, len1 - a1Offset);
length = Math.max(length, 0);
result |= 0x00FF;
}
if (len2 < (a2Offset + length)) {
length = Math.min(length, len2 - a2Offset);
length = Math.max(length, 0);
result |= 0xFF00;
}
for (int cmpLen = length; cmpLen > 0; a1Offset++, a2Offset++, cmpLen--) {
result |= a1[a1Offset] ^ a2[a2Offset];
}
return result == 0;
}
}