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1
2 package ch.ethz.ssh2.crypto;
3
4 import java.io.CharArrayWriter  ;
5 import java.io.IOException ;
6
7
13 public class Base64
14 {
15 static final char[] alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
16
17 public static char[] encode(byte[] content)
18 {
19 CharArrayWriter cw = new CharArrayWriter ((4 * content.length) / 3);
20
21 int idx = 0;
22
23 int x = 0;
24
25 for (int i = 0; i < content.length; i++)
26 {
27 if (idx == 0)
28 x = (content[i] & 0xff) << 16;
29 else if (idx == 1)
30 x = x | ((content[i] & 0xff) << 8);
31 else
32 x = x | (content[i] & 0xff);
33
34 idx++;
35
36 if (idx == 3)
37 {
38 cw.write(alphabet[x >> 18]);
39 cw.write(alphabet[(x >> 12) & 0x3f]);
40 cw.write(alphabet[(x >> 6) & 0x3f]);
41 cw.write(alphabet[x & 0x3f]);
42
43 idx = 0;
44 }
45 }
46
47 if (idx == 1)
48 {
49 cw.write(alphabet[x >> 18]);
50 cw.write(alphabet[(x >> 12) & 0x3f]);
51 cw.write('=');
52 cw.write('=');
53 }
54
55 if (idx == 2)
56 {
57 cw.write(alphabet[x >> 18]);
58 cw.write(alphabet[(x >> 12) & 0x3f]);
59 cw.write(alphabet[(x >> 6) & 0x3f]);
60 cw.write('=');
61 }
62
63 return cw.toCharArray();
64 }
65
66 public static byte[] decode(char[] message) throws IOException
67 {
68 byte buff[] = new byte[4];
69 byte dest[] = new byte[message.length];
70
71 int bpos = 0;
72 int destpos = 0;
73
74 for (int i = 0; i < message.length; i++)
75 {
76 int c = message[i];
77
78 if ((c == '\n') || (c == '\r') || (c == ' ') || (c == '\t'))
79 continue;
80
81 if ((c >= 'A') && (c <= 'Z'))
82 {
83 buff[bpos++] = (byte) (c - 'A');
84 }
85 else if ((c >= 'a') && (c <= 'z'))
86 {
87 buff[bpos++] = (byte) ((c - 'a') + 26);
88 }
89 else if ((c >= '0') && (c <= '9'))
90 {
91 buff[bpos++] = (byte) ((c - '0') + 52);
92 }
93 else if (c == '+')
94 {
95 buff[bpos++] = 62;
96 }
97 else if (c == '/')
98 {
99 buff[bpos++] = 63;
100 }
101 else if (c == '=')
102 {
103 buff[bpos++] = 64;
104 }
105 else
106 {
107 throw new IOException ("Illegal char in base64 code.");
108 }
109
110 if (bpos == 4)
111 {
112 bpos = 0;
113
114 if (buff[0] == 64)
115 break;
116
117 if (buff[1] == 64)
118 throw new IOException ("Unexpected '=' in base64 code.");
119
120 if (buff[2] == 64)
121 {
122 int v = (((buff[0] & 0x3f) << 6) | ((buff[1] & 0x3f)));
123 dest[destpos++] = (byte) (v >> 4);
124 break;
125 }
126 else if (buff[3] == 64)
127 {
128 int v = (((buff[0] & 0x3f) << 12) | ((buff[1] & 0x3f) << 6) | ((buff[2] & 0x3f)));
129 dest[destpos++] = (byte) (v >> 10);
130 dest[destpos++] = (byte) (v >> 2);
131 break;
132 }
133 else
134 {
135 int v = (((buff[0] & 0x3f) << 18) | ((buff[1] & 0x3f) << 12) | ((buff[2] & 0x3f) << 6) | ((buff[3] & 0x3f)));
136 dest[destpos++] = (byte) (v >> 16);
137 dest[destpos++] = (byte) (v >> 8);
138 dest[destpos++] = (byte) (v);
139 }
140 }
141 }
142
143 byte[] res = new byte[destpos];
144 System.arraycopy(dest, 0, res, 0, destpos);
145
146 return res;
147 }
148 }
149 |
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