1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 /*
20 * The apr_md5_encode() routine in the APR project's apr_md5.c file uses much
21 * code obtained from the FreeBSD 3.0 MD5 crypt() function, which is licenced
22 * as follows:
23 * ----------------------------------------------------------------------------
24 * "THE BEER-WARE LICENSE" (Revision 42):
25 * <phk@login.dknet.dk> wrote this file. As long as you retain this notice you
26 * can do whatever you want with this stuff. If we meet some day, and you think
27 * this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp
28 * ----------------------------------------------------------------------------
29 */
30 package org.apache.shiro.codec;
31
32 import java.io.IOException;
33
34 /**
35 * Codec for <a href="http://en.wikipedia.org/wiki/Crypt_(Unix)">Unix Crypt</a>-style encoding. While similar to
36 * Base64, it is not compatible with Base64.
37 * <p/>
38 * This implementation is based on encoding algorithms found in the Apache Portable Runtime library's
39 * <a href="http://svn.apache.org/viewvc/apr/apr/trunk/crypto/apr_md5.c?revision=HEAD&view=markup">apr_md5.c</a>
40 * implementation for its {@code crypt}-style support. The APR team in turn received inspiration for its encoding
41 * implementation based on FreeBSD 3.0's {@code /usr/src/lib/libcrypt/crypt.c} implementation. The
42 * accompanying license headers have been retained at the top of this source file.
43 * <p/>
44 * This file and all that it contains is ASL 2.0 compatible.
45 *
46 * @since 1.2
47 */
48 public class H64 {
49
50 private static final char[] itoa64 = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz".toCharArray();
51
52 private static short toShort(byte b) {
53 return (short) (b & 0xff);
54 }
55
56 private static int toInt(byte[] bytes, int offset, int numBytes) {
57 if (numBytes < 1 || numBytes > 4) {
58 throw new IllegalArgumentException("numBytes must be between 1 and 4.");
59 }
60 int val = toShort(bytes[offset]); //1st byte
61 for (int i = 1; i < numBytes; i++) { //any remaining bytes:
62 short s = toShort(bytes[offset + i]);
63 switch (i) {
64 case 1: val |= s << 8; break;
65 case 2: val |= s << 16; break;
66 case 3: val |= s << 24; break;
67 }
68 }
69 return val;
70 }
71
72 /**
73 * Appends the specified character into the buffer, rethrowing any encountered
74 * {@link IOException} as an {@link IllegalStateException} (since this method is used for internal
75 * implementation needs and we only ever use StringBuilders, we should never encounter an IOException).
76 *
77 * @param buf the buffer to append to
78 * @param c the character to append.
79 */
80 private static void append(Appendable buf, char c) {
81 try {
82 buf.append(c);
83 } catch (IOException e) {
84 throw new IllegalStateException("Unable to append character to internal buffer.", e);
85 }
86 }
87
88 /**
89 * Encodes the specified integer to {@code numChars} H64-compatible characters and appends them into {@code buf}.
90 *
91 * @param value the integer to encode to H64-compatible characters
92 * @param buf the output buffer
93 * @param numChars the number of characters the value should be converted to. 3, 2 or 1.
94 */
95 private static void encodeAndAppend(int value, Appendable buf, int numChars) {
96 for (int i = 0; i < numChars; i++) {
97 append(buf, itoa64[value & 0x3f]);
98 value >>= 6;
99 }
100 }
101
102 /**
103 * Encodes the specified bytes to an {@code H64}-encoded String.
104 *
105 * @param bytes
106 * @return
107 */
108 public static String encodeToString(byte[] bytes) {
109 if (bytes == null || bytes.length == 0) return null;
110
111 StringBuilder buf = new StringBuilder();
112
113 int length = bytes.length;
114 int remainder = length % 3;
115 int i = 0; //starting byte
116 int last3ByteIndex = length - remainder; //last byte whose index is a multiple of 3
117
118 for(; i < last3ByteIndex; i += 3) {
119 int twentyFourBit = toInt(bytes, i, 3);
120 encodeAndAppend(twentyFourBit, buf, 4);
121 }
122 if (remainder > 0) {
123 //one or two bytes that we still need to encode:
124 int a = toInt(bytes, i, remainder);
125 encodeAndAppend(a, buf, remainder + 1);
126 }
127 return buf.toString();
128 }
129 }