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.nio.charset.StandardCharsets;
020import java.security.SecureRandom;
021import java.util.concurrent.ThreadLocalRandom;
022
023/**
024 * GNU libc crypt(3) compatible hash method.
025 * <p>
026 * See {@link #crypt(String, String)} for further details.
027 * <p>
028 * This class is immutable and thread-safe.
029 *
030 * @since 1.7
031 */
032public class Crypt {
033
034    /**
035     * Encrypts a password in a crypt(3) compatible way.
036     * <p>
037     * A random salt and the default algorithm (currently SHA-512) are used. See {@link #crypt(String, String)} for
038     * details.
039     * </p>
040     * <p>
041     * A salt is generated for you using {@link ThreadLocalRandom}; for more secure salts consider using
042     * {@link SecureRandom} to generate your own salts and calling {@link #crypt(byte[], String)}.
043     * </p>
044     *
045     * @param keyBytes
046     *            plaintext password
047     * @return hash value
048     * @throws IllegalArgumentException
049     *             when a {@link java.security.NoSuchAlgorithmException} is caught.
050     */
051    public static String crypt(final byte[] keyBytes) {
052        return crypt(keyBytes, null);
053    }
054
055    /**
056     * Encrypts a password in a crypt(3) compatible way.
057     * <p>
058     * If no salt is provided, a random salt and the default algorithm (currently SHA-512) will be used. See
059     * {@link #crypt(String, String)} for details.
060     *
061     * @param keyBytes
062     *            plaintext password
063     * @param salt
064     *            real salt value without prefix or "rounds=". The salt may be null,
065     *            in which case a salt is generated for you using {@link ThreadLocalRandom};
066     *            for more secure salts consider using {@link SecureRandom} to
067     *            generate your own salts.
068     * @return hash value
069     * @throws IllegalArgumentException
070     *             if the salt does not match the allowed pattern
071     * @throws IllegalArgumentException
072     *             when a {@link java.security.NoSuchAlgorithmException} is caught.
073     */
074    public static String crypt(final byte[] keyBytes, final String salt) {
075        if (salt == null) {
076            return Sha2Crypt.sha512Crypt(keyBytes);
077        } else if (salt.startsWith(Sha2Crypt.SHA512_PREFIX)) {
078            return Sha2Crypt.sha512Crypt(keyBytes, salt);
079        } else if (salt.startsWith(Sha2Crypt.SHA256_PREFIX)) {
080            return Sha2Crypt.sha256Crypt(keyBytes, salt);
081        } else if (salt.startsWith(Md5Crypt.MD5_PREFIX)) {
082            return Md5Crypt.md5Crypt(keyBytes, salt);
083        } else {
084            return UnixCrypt.crypt(keyBytes, salt);
085        }
086    }
087
088    /**
089     * Calculates the digest using the strongest crypt(3) algorithm.
090     * <p>
091     * A random salt and the default algorithm (currently SHA-512) are used.
092     * </p>
093     * <p>
094     * A salt is generated for you using {@link ThreadLocalRandom}; for more secure salts consider using
095     * {@link SecureRandom} to generate your own salts and calling {@link #crypt(String, String)}.
096     * </p>
097     *
098     * @see #crypt(String, String)
099     * @param key
100     *            plaintext password
101     * @return hash value
102     * @throws IllegalArgumentException
103     *             when a {@link java.security.NoSuchAlgorithmException} is caught.
104     */
105    public static String crypt(final String key) {
106        return crypt(key, null);
107    }
108
109    /**
110     * Encrypts a password in a crypt(3) compatible way.
111     * <p>
112     * The exact algorithm depends on the format of the salt string:
113     * <ul>
114     * <li>SHA-512 salts start with {@code $6$} and are up to 16 chars long.
115     * <li>SHA-256 salts start with {@code $5$} and are up to 16 chars long
116     * <li>MD5 salts start with {@code $1$} and are up to 8 chars long
117     * <li>DES, the traditional UnixCrypt algorithm is used with only 2 chars
118     * <li>Only the first 8 chars of the passwords are used in the DES algorithm!
119     * </ul>
120     * The magic strings {@code "$apr1$"} and {@code "$2a$"} are not recognized by this method as its output should be
121     * identical with that of the libc implementation.
122     * <p>
123     * 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
124     * {@code "$"} sign is encountered. It is therefore valid to enter a complete hash value as salt to e.g. verify a
125     * password with:
126     *
127     * <pre>
128     * storedPwd.equals(crypt(enteredPwd, storedPwd))
129     * </pre>
130     * <p>
131     * The resulting string starts with the marker string ({@code $n$}), where n is the same as the input salt.
132     * The salt is then appended, followed by a {@code "$"} sign.
133     * This is followed by the actual hash value.
134     * For DES the string only contains the salt and actual hash.
135     * The total length is dependent on the algorithm used:
136     * <ul>
137     * <li>SHA-512: 106 chars
138     * <li>SHA-256: 63 chars
139     * <li>MD5: 34 chars
140     * <li>DES: 13 chars
141     * </ul>
142     * <p>
143     * Example:
144     *
145     * <pre>
146     *      crypt("secret", "$1$xxxx") =&gt; "$1$xxxx$aMkevjfEIpa35Bh3G4bAc."
147     *      crypt("secret", "xx") =&gt; "xxWAum7tHdIUw"
148     * </pre>
149     * <p>
150     * This method comes in a variation that accepts a byte[] array to support input strings that are not encoded in
151     * UTF-8 but e.g. in ISO-8859-1 where equal characters result in different byte values.
152     *
153     * @see "The man page of the libc crypt (3) function."
154     * @param key
155     *            plaintext password as entered by the used
156     * @param salt
157     *            real salt value without prefix or "rounds=". The salt may be null, in which case a
158     *            salt is generated for you using {@link ThreadLocalRandom}; for more secure salts
159     *            consider using {@link SecureRandom} to generate your own salts.
160     * @return hash value, i.e. encrypted password including the salt string
161     * @throws IllegalArgumentException
162     *             if the salt does not match the allowed pattern
163     * @throws IllegalArgumentException
164     *             when a {@link java.security.NoSuchAlgorithmException} is caught. *
165     */
166    public static String crypt(final String key, final String salt) {
167        return crypt(key.getBytes(StandardCharsets.UTF_8), salt);
168    }
169}