    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.codec.digest;
    018
    019import java.security.SecureRandom;
    020import java.util.concurrent.ThreadLocalRandom;
    021
    022import org.apache.commons.codec.Charsets;
    023
    024/**
    025 * GNU libc crypt(3) compatible hash method.
    026 * <p>
    027 * See {@link #crypt(String, String)} for further details.
    028 * <p>
    029 * This class is immutable and thread-safe.
    030 *
    031 * @version $Id$
    032 * @since 1.7
    033 */
    034public class Crypt {
    035
    036    /**
    037     * Encrypts a password in a crypt(3) compatible way.
    038     * <p>
    039     * A random salt and the default algorithm (currently SHA-512) are used. See {@link #crypt(String, String)} for
    040     * details.
    041     * </p>
    042     * <p>
    043     * A salt is generated for you using {@link ThreadLocalRandom}; for more secure salts consider using
    044     * {@link SecureRandom} to generate your own salts and calling {@link #crypt(byte[], String)}.
    045     * </p>
    046     *
    047     * @param keyBytes
    048     *            plaintext password
    049     * @return hash value
    050     * @throws IllegalArgumentException
    051     *             when a {@link java.security.NoSuchAlgorithmException} is caught.
    052     */
    053    public static String crypt(final byte[] keyBytes) {
    054        return crypt(keyBytes, null);
    055    }
    056
    057    /**
    058     * Encrypts a password in a crypt(3) compatible way.
    059     * <p>
    060     * If no salt is provided, a random salt and the default algorithm (currently SHA-512) will be used. See
    061     * {@link #crypt(String, String)} for details.
    062     *
    063     * @param keyBytes
    064     *            plaintext password
    065     * @param salt
    066     *            real salt value without prefix or "rounds=". The salt may be null, in which case a salt is generated for
    067     *            you using {@link ThreadLocalRandom}; for more secure salts consider using {@link SecureRandom} to
    068     *            generate your own salts.
    069     * @return hash value
    070     * @throws IllegalArgumentException
    071     *             if the salt does not match the allowed pattern
    072     * @throws IllegalArgumentException
    073     *             when a {@link java.security.NoSuchAlgorithmException} is caught.
    074     */
    075    public static String crypt(final byte[] keyBytes, final String salt) {
    076        if (salt == null) {
    077            return Sha2Crypt.sha512Crypt(keyBytes);
    078        } else if (salt.startsWith(Sha2Crypt.SHA512_PREFIX)) {
    079            return Sha2Crypt.sha512Crypt(keyBytes, salt);
    080        } else if (salt.startsWith(Sha2Crypt.SHA256_PREFIX)) {
    081            return Sha2Crypt.sha256Crypt(keyBytes, salt);
    082        } else if (salt.startsWith(Md5Crypt.MD5_PREFIX)) {
    083            return Md5Crypt.md5Crypt(keyBytes, salt);
    084        } else {
    085            return UnixCrypt.crypt(keyBytes, salt);
    086        }
    087    }
    088
    089    /**
    090     * Calculates the digest using the strongest crypt(3) algorithm.
    091     * <p>
    092     * A random salt and the default algorithm (currently SHA-512) are used.
    093     * </p>
    094     * <p>
    095     * A salt is generated for you using {@link ThreadLocalRandom}; for more secure salts consider using
    096     * {@link SecureRandom} to generate your own salts and calling {@link #crypt(String, String)}.
    097     * </p>
    098     *
    099     * @see #crypt(String, String)
    100     * @param key
    101     *            plaintext password
    102     * @return hash value
    103     * @throws IllegalArgumentException
    104     *             when a {@link java.security.NoSuchAlgorithmException} is caught.
    105     */
    106    public static String crypt(final String key) {
    107        return crypt(key, null);
    108    }
    109
    110    /**
    111     * Encrypts a password in a crypt(3) compatible way.
    112     * <p>
    113     * The exact algorithm depends on the format of the salt string:
    114     * <ul>
    115     * <li>SHA-512 salts start with {@code $6$} and are up to 16 chars long.
    116     * <li>SHA-256 salts start with {@code $5$} and are up to 16 chars long
    117     * <li>MD5 salts start with {@code $1$} and are up to 8 chars long
    118     * <li>DES, the traditional UnixCrypt algorithm is used with only 2 chars
    119     * <li>Only the first 8 chars of the passwords are used in the DES algorithm!
    120     * </ul>
    121     * The magic strings {@code "$apr1$"} and {@code "$2a$"} are not recognized by this method as its output should be
    122     * identical with that of the libc implementation.
    123     * <p>
    124     * The rest of the salt string is drawn from the set {@code [a-zA-Z0-9./]} and is cut at the maximum length of if a
    125     * {@code "$"} sign is encountered. It is therefore valid to enter a complete hash value as salt to e.g. verify a
    126     * password with:
    127     *
    128     * <pre>
    129     * storedPwd.equals(crypt(enteredPwd, storedPwd))
    130     * </pre>
    131     * <p>
    132     * The resulting string starts with the marker string ({@code $n$}), where n is the same as the input salt.
    133     * The salt is then appended, followed by a {@code "$"} sign.
    134     * This is followed by the actual hash value.
    135     * For DES the string only contains the salt and actual hash.
    136     * The total length is dependent on the algorithm used:
    137     * <ul>
    138     * <li>SHA-512: 106 chars
    139     * <li>SHA-256: 63 chars
    140     * <li>MD5: 34 chars
    141     * <li>DES: 13 chars
    142     * </ul>
    143     * <p>
    144     * Example:
    145     *
    146     * <pre>
    147     *      crypt("secret", "$1$xxxx") =&gt; "$1$xxxx$aMkevjfEIpa35Bh3G4bAc."
    148     *      crypt("secret", "xx") =&gt; "xxWAum7tHdIUw"
    149     * </pre>
    150     * <p>
    151     * This method comes in a variation that accepts a byte[] array to support input strings that are not encoded in
    152     * UTF-8 but e.g. in ISO-8859-1 where equal characters result in different byte values.
    153     *
    154     * @see "The man page of the libc crypt (3) function."
    155     * @param key
    156     *            plaintext password as entered by the used
    157     * @param salt
    158     *            real salt value without prefix or "rounds=". The salt may be null, in which case a salt is generated for
    159     *            you using {@link ThreadLocalRandom}; for more secure salts consider using {@link SecureRandom} to
    160     *            generate your own salts.
    161     * @return hash value, i.e. encrypted password including the salt string
    162     * @throws IllegalArgumentException
    163     *             if the salt does not match the allowed pattern
    164     * @throws IllegalArgumentException
    165     *             when a {@link java.security.NoSuchAlgorithmException} is caught. *
    166     */
    167    public static String crypt(final String key, final String salt) {
    168        return crypt(key.getBytes(Charsets.UTF_8), salt);
    169    }
    170}