1 package org.itracker.util;
2
3 /**
4 * A Base64 Encoder/Decoder.
5 * <p/>
6 * <p/>
7 * This class is used to encode and decode data in Base64 format as described in RFC 1521.
8 * <p/>
9 * <p/>
10 * This is "Open Source" software and released under the <a href="http://www.gnu.org/licenses/lgpl.html">GNU/LGPL</a> license.<br>
11 * It is provided "as is" without warranty of any kind.<br>
12 * Copyright 2003: Christian d'Heureuse, Inventec Informatik AG, Switzerland.<br>
13 * Home page: <a href="http://www.source-code.biz">www.source-code.biz</a><br>
14 * <p/>
15 * <p/>
16 * Version history:<br>
17 * 2003-07-22 Christian d'Heureuse (chdh): Module created.<br>
18 * 2005-08-11 chdh: Lincense changed from GPL to LGPL.<br>
19 * 2006-11-21 chdh:<br>
20 * Method encode(String) renamed to encodeString(String).<br>
21 * Method decode(String) renamed to decodeString(String).<br>
22 * New method encode(byte[],int) added.<br>
23 * New method decode(String) added.<br>
24 */
25
26 public class Base64Coder {
27
28 // Mapping table from 6-bit nibbles to Base64 characters.
29 private static char[] map1 = new char[64];
30
31 static {
32 int i = 0;
33 for (char c = 'A'; c <= 'Z'; c++) map1[i++] = c;
34 for (char c = 'a'; c <= 'z'; c++) map1[i++] = c;
35 for (char c = '0'; c <= '9'; c++) map1[i++] = c;
36 map1[i++] = '+';
37 map1[i++] = '/';
38 }
39
40 // Mapping table from Base64 characters to 6-bit nibbles.
41 private static byte[] map2 = new byte[128];
42
43 static {
44 for (int i = 0; i < map2.length; i++) map2[i] = -1;
45 for (int i = 0; i < 64; i++) map2[map1[i]] = (byte) i;
46 }
47
48 /**
49 * Encodes a string into Base64 format.
50 * No blanks or line breaks are inserted.
51 *
52 * @param s a String to be encoded.
53 * @return A String with the Base64 encoded data.
54 */
55 public static String encodeString(String s) {
56 return new String(encode(s.getBytes()));
57 }
58
59 /**
60 * Encodes a byte array into Base64 format.
61 * No blanks or line breaks are inserted.
62 *
63 * @param in an array containing the data bytes to be encoded.
64 * @return A character array with the Base64 encoded data.
65 */
66 public static char[] encode(byte[] in) {
67 return encode(in, in.length);
68 }
69
70 /**
71 * Encodes a byte array into Base64 format.
72 * No blanks or line breaks are inserted.
73 *
74 * @param in an array containing the data bytes to be encoded.
75 * @param iLen number of bytes to process in <code>in</code>.
76 * @return A character array with the Base64 encoded data.
77 */
78 public static char[] encode(byte[] in, int iLen) {
79 int oDataLen = (iLen * 4 + 2) / 3; // output length without padding
80 int oLen = ((iLen + 2) / 3) * 4; // output length including padding
81 char[] out = new char[oLen];
82 int ip = 0;
83 int op = 0;
84 while (ip < iLen) {
85 int i0 = in[ip++] & 0xff;
86 int i1 = ip < iLen ? in[ip++] & 0xff : 0;
87 int i2 = ip < iLen ? in[ip++] & 0xff : 0;
88 int o0 = i0 >>> 2;
89 int o1 = ((i0 & 3) << 4) | (i1 >>> 4);
90 int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
91 int o3 = i2 & 0x3F;
92 out[op++] = map1[o0];
93 out[op++] = map1[o1];
94 out[op] = op < oDataLen ? map1[o2] : '=';
95 op++;
96 out[op] = op < oDataLen ? map1[o3] : '=';
97 op++;
98 }
99 return out;
100 }
101
102 /**
103 * Decodes a string from Base64 format.
104 *
105 * @param s a Base64 String to be decoded.
106 * @return A String containing the decoded data.
107 * @throws IllegalArgumentException if the input is not valid Base64 encoded data.
108 */
109 public static String decodeString(String s) {
110 return new String(decode(s));
111 }
112
113 /**
114 * Decodes a byte array from Base64 format.
115 *
116 * @param s a Base64 String to be decoded.
117 * @return An array containing the decoded data bytes.
118 * @throws IllegalArgumentException if the input is not valid Base64 encoded data.
119 */
120 public static byte[] decode(String s) {
121 return decode(s.toCharArray());
122 }
123
124 /**
125 * Decodes a byte array from Base64 format.
126 * No blanks or line breaks are allowed within the Base64 encoded data.
127 *
128 * @param in a character array containing the Base64 encoded data.
129 * @return An array containing the decoded data bytes.
130 * @throws IllegalArgumentException if the input is not valid Base64 encoded data.
131 */
132 public static byte[] decode(char[] in) {
133 int iLen = in.length;
134 if (iLen % 4 != 0)
135 throw new IllegalArgumentException("Length of Base64 encoded input string is not a multiple of 4.");
136 while (iLen > 0 && in[iLen - 1] == '=') iLen--;
137 int oLen = (iLen * 3) / 4;
138 byte[] out = new byte[oLen];
139 int ip = 0;
140 int op = 0;
141 while (ip < iLen) {
142 int i0 = in[ip++];
143 int i1 = in[ip++];
144 int i2 = ip < iLen ? in[ip++] : 'A';
145 int i3 = ip < iLen ? in[ip++] : 'A';
146 if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
147 throw new IllegalArgumentException("Illegal character in Base64 encoded data.");
148 int b0 = map2[i0];
149 int b1 = map2[i1];
150 int b2 = map2[i2];
151 int b3 = map2[i3];
152 if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
153 throw new IllegalArgumentException("Illegal character in Base64 encoded data.");
154 int o0 = (b0 << 2) | (b1 >>> 4);
155 int o1 = ((b1 & 0xf) << 4) | (b2 >>> 2);
156 int o2 = ((b2 & 3) << 6) | b3;
157 out[op++] = (byte) o0;
158 if (op < oLen) out[op++] = (byte) o1;
159 if (op < oLen) out[op++] = (byte) o2;
160 }
161 return out;
162 }
163
164 // Dummy constructor.
165 private Base64Coder() {
166 }
167
168 } // end class Base64Coder