/*
* Copyright 2011-2016 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 static org.springframework.security.crypto.util.EncodingUtils.concatenate;
import static org.springframework.security.crypto.util.EncodingUtils.subArray;
import org.springframework.security.crypto.codec.Hex;
import org.springframework.security.crypto.codec.Utf8;
import org.springframework.security.crypto.keygen.BytesKeyGenerator;
import org.springframework.security.crypto.keygen.KeyGenerators;
/**
* A standard {@code PasswordEncoder} implementation that uses SHA-256 hashing with 1024
* iterations and a random 8-byte random salt value. It uses an additional system-wide
* secret value to provide additional protection.
* <p>
* The digest algorithm is invoked on the concatenated bytes of the salt, secret and
* password.
* <p>
* If you are developing a new system,
* {@link org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder} is a better
* choice both in terms of security and interoperability with other languages.
*
* @author Keith Donald
* @author Luke Taylor
*/
public final class StandardPasswordEncoder implements PasswordEncoder {
private final Digester digester;
private final byte[] secret;
private final BytesKeyGenerator saltGenerator;
/**
* Constructs a standard password encoder with no additional secret value.
*/
public StandardPasswordEncoder() {
this("");
}
/**
* Constructs a standard password encoder with a secret value which is also included
* in the password hash.
*
* @param secret the secret key used in the encoding process (should not be shared)
*/
public StandardPasswordEncoder(CharSequence secret) {
this("SHA-256", secret);
}
public String encode(CharSequence rawPassword) {
return encode(rawPassword, saltGenerator.generateKey());
}
public boolean matches(CharSequence rawPassword, String encodedPassword) {
byte[] digested = decode(encodedPassword);
byte[] salt = subArray(digested, 0, saltGenerator.getKeyLength());
return matches(digested, digest(rawPassword, salt));
}
// internal helpers
private StandardPasswordEncoder(String algorithm, CharSequence secret) {
this.digester = new Digester(algorithm, DEFAULT_ITERATIONS);
this.secret = Utf8.encode(secret);
this.saltGenerator = KeyGenerators.secureRandom();
}
private String encode(CharSequence rawPassword, byte[] salt) {
byte[] digest = digest(rawPassword, salt);
return new String(Hex.encode(digest));
}
private byte[] digest(CharSequence rawPassword, byte[] salt) {
byte[] digest = digester.digest(concatenate(salt, secret,
Utf8.encode(rawPassword)));
return concatenate(salt, digest);
}
private byte[] decode(CharSequence encodedPassword) {
return Hex.decode(encodedPassword);
}
/**
* Constant time comparison to prevent against timing attacks.
*/
private 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;
}
private static final int DEFAULT_ITERATIONS = 1024;
}