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 package org.apache.shiro.codec;
20
21 /**
22 * <a href="http://en.wikipedia.org/wiki/Hexadecimal">Hexadecimal</a> encoder and decoder.
23 * <p/>
24 * This class was borrowed from Apache Commons Codec SVN repository (rev. {@code 560660}) with modifications
25 * to enable Hex conversion without a full dependency on Commons Codec. We didn't want to reinvent the wheel of
26 * great work they've done, but also didn't want to force every Shiro user to depend on the commons-codec.jar
27 * <p/>
28 * As per the Apache 2.0 license, the original copyright notice and all author and copyright information have
29 * remained in tact.
30 *
31 * @see <a href="http://en.wikipedia.org/wiki/Hexadecimal">Wikipedia: Hexadecimal</a>
32 * @since 0.9
33 */
34 public class Hex {
35
36 /**
37 * Used to build output as Hex
38 */
39 private static final char[] DIGITS = {
40 '0', '1', '2', '3', '4', '5', '6', '7',
41 '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
42 };
43
44 /**
45 * Encodes the specifed byte array to a character array and then returns that character array
46 * as a String.
47 *
48 * @param bytes the byte array to Hex-encode.
49 * @return A String representation of the resultant hex-encoded char array.
50 */
51 public static String encodeToString(byte[] bytes) {
52 char[] encodedChars = encode(bytes);
53 return new String(encodedChars);
54 }
55
56 /**
57 * Converts an array of bytes into an array of characters representing the hexidecimal values of each byte in order.
58 * The returned array will be double the length of the passed array, as it takes two characters to represent any
59 * given byte.
60 *
61 * @param data byte[] to convert to Hex characters
62 * @return A char[] containing hexidecimal characters
63 */
64 public static char[] encode(byte[] data) {
65
66 int l = data.length;
67
68 char[] out = new char[l << 1];
69
70 // two characters form the hex value.
71 for (int i = 0, j = 0; i < l; i++) {
72 out[j++] = DIGITS[(0xF0 & data[i]) >>> 4];
73 out[j++] = DIGITS[0x0F & data[i]];
74 }
75
76 return out;
77 }
78
79 /**
80 * Converts an array of character bytes representing hexidecimal values into an
81 * array of bytes of those same values. The returned array will be half the
82 * length of the passed array, as it takes two characters to represent any
83 * given byte. An exception is thrown if the passed char array has an odd
84 * number of elements.
85 *
86 * @param array An array of character bytes containing hexidecimal digits
87 * @return A byte array containing binary data decoded from
88 * the supplied byte array (representing characters).
89 * @throws IllegalArgumentException Thrown if an odd number of characters is supplied
90 * to this function
91 * @see #decode(char[])
92 */
93 public static byte[] decode(byte[] array) throws IllegalArgumentException {
94 String s = CodecSupport.toString(array);
95 return decode(s);
96 }
97
98 /**
99 * Converts the specified Hex-encoded String into a raw byte array. This is a
100 * convenience method that merely delegates to {@link #decode(char[])} using the
101 * argument's hex.toCharArray() value.
102 *
103 * @param hex a Hex-encoded String.
104 * @return A byte array containing binary data decoded from the supplied String's char array.
105 */
106 public static byte[] decode(String hex) {
107 return decode(hex.toCharArray());
108 }
109
110 /**
111 * Converts an array of characters representing hexidecimal values into an
112 * array of bytes of those same values. The returned array will be half the
113 * length of the passed array, as it takes two characters to represent any
114 * given byte. An exception is thrown if the passed char array has an odd
115 * number of elements.
116 *
117 * @param data An array of characters containing hexidecimal digits
118 * @return A byte array containing binary data decoded from
119 * the supplied char array.
120 * @throws IllegalArgumentException if an odd number or illegal of characters
121 * is supplied
122 */
123 public static byte[] decode(char[] data) throws IllegalArgumentException {
124
125 int len = data.length;
126
127 if ((len & 0x01) != 0) {
128 throw new IllegalArgumentException("Odd number of characters.");
129 }
130
131 byte[] out = new byte[len >> 1];
132
133 // two characters form the hex value.
134 for (int i = 0, j = 0; j < len; i++) {
135 int f = toDigit(data[j], j) << 4;
136 j++;
137 f = f | toDigit(data[j], j);
138 j++;
139 out[i] = (byte) (f & 0xFF);
140 }
141
142 return out;
143 }
144
145 /**
146 * Converts a hexadecimal character to an integer.
147 *
148 * @param ch A character to convert to an integer digit
149 * @param index The index of the character in the source
150 * @return An integer
151 * @throws IllegalArgumentException if ch is an illegal hex character
152 */
153 protected static int toDigit(char ch, int index) throws IllegalArgumentException {
154 int digit = Character.digit(ch, 16);
155 if (digit == -1) {
156 throw new IllegalArgumentException("Illegal hexadecimal charcter " + ch + " at index " + index);
157 }
158 return digit;
159 }
160
161
162 }