com.springsource.greenhouse.account.GreenhousePasswordEncoder.java Source code

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Here is the source code for com.springsource.greenhouse.account.GreenhousePasswordEncoder.java

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/*
 * Copyright 2010-2011 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 com.springsource.greenhouse.account;

import static org.springframework.security.crypto.util.EncodingUtils.concatenate;
import static org.springframework.security.crypto.util.EncodingUtils.subArray;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.util.Arrays;

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;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.security.crypto.password.StandardPasswordEncoder;

/**
 * A PasswordEncoder implementation that uses SHA-256 hashing implemented by the Sun provider with 8-byte random salting by default.
 * Compatibility note: this implementation does NOT perform digest iterations e.g. 1024 iterations.
 * This is for compatibility with the existing password database.
 * See {@link StandardPasswordEncoder} for an implementation that does perform digest iteration correctly (which makes its digests more secure).
 * @author Keith Donald
 * @see StandardPasswordEncoder
 */
public class GreenhousePasswordEncoder implements PasswordEncoder {

    private final Digester digester;

    private final byte[] secret;

    private final BytesKeyGenerator saltGenerator;

    /**
     * Constructs a standard password encoder.
     * @param secret the secret key used in the encoding process
     */
    public GreenhousePasswordEncoder(String secret) {
        this("SHA-256", "SUN", secret);
    }

    /**
     * Creates a fully customized standard password encoder.
     */
    public GreenhousePasswordEncoder(String algorithm, String provider, String secret) {
        this.digester = new Digester(algorithm, provider);
        this.secret = Utf8.encode(secret);
        this.saltGenerator = KeyGenerators.secureRandom();
    }

    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 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(String encodedPassword) {
        return Hex.decode(encodedPassword);
    }

    private boolean matches(byte[] expected, byte[] actual) {
        return Arrays.equals(expected, actual);
    }

    private static class Digester {

        private final MessageDigest messageDigest;

        public Digester(String algorithm, String provider) {
            try {
                messageDigest = MessageDigest.getInstance(algorithm, provider);
            } catch (NoSuchAlgorithmException e) {
                throw new IllegalStateException("No such hashing algorithm", e);
            } catch (NoSuchProviderException e) {
                throw new IllegalStateException("No such provider for hashing algorithm", e);
            }
        }

        public byte[] digest(byte[] value) {
            // at least 1024 iterations should be applied here for additional security against brute-force attacks.
            // Unfortunately this was not done when the password database was populated.
            // Thus, we need to preserve compatible digest behavior.
            synchronized (messageDigest) {
                return messageDigest.digest(value);
            }
        }

    }

}