/*
* Copyright 2002-2016 the original author or authors.
*
* Licensed 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.springframework.security.crypto.password;
import org.springframework.security.crypto.codec.Hex;
import org.springframework.security.crypto.keygen.BytesKeyGenerator;
import org.springframework.security.crypto.keygen.KeyGenerators;
import static org.springframework.security.crypto.util.EncodingUtils.concatenate;
import static org.springframework.security.crypto.util.EncodingUtils.subArray;
/**
* Abstract base class for password encoders
*
* @author Rob Worsnop
*/
public abstract class AbstractPasswordEncoder implements PasswordEncoder {
private final BytesKeyGenerator saltGenerator;
protected AbstractPasswordEncoder() {
this.saltGenerator = KeyGenerators.secureRandom();
}
@Override
public String encode(CharSequence rawPassword) {
byte[] salt = this.saltGenerator.generateKey();
byte[] encoded = encodeAndConcatenate(rawPassword, salt);
return String.valueOf(Hex.encode(encoded));
}
@Override
public boolean matches(CharSequence rawPassword, String encodedPassword) {
byte[] digested = Hex.decode(encodedPassword);
byte[] salt = subArray(digested, 0, this.saltGenerator.getKeyLength());
return matches(digested, encodeAndConcatenate(rawPassword, salt));
}
protected abstract byte[] encode(CharSequence rawPassword, byte[] salt);
protected byte[] encodeAndConcatenate(CharSequence rawPassword, byte[] salt) {
return concatenate(salt, encode(rawPassword, salt));
}
/**
* Constant time comparison to prevent against timing attacks.
*/
protected static boolean matches(byte[] expected, byte[] actual) {
if (expected.length != actual.length) {
return false;
}
int result = 0;
for (int i = 0; i < expected.length; i++) {
result |= expected[i] ^ actual[i];
}
return result == 0;
}
}