src/com/trilead/ssh2/crypto/Base64.java

   1 \r
   2 package com.trilead.ssh2.crypto;\r
   3 \r
   4 import java.io.CharArrayWriter;\r
   5 import java.io.IOException;\r
   6 \r
   7 /**\r
   8  * Basic Base64 Support.\r
   9  * \r
  10  * @author Christian Plattner, plattner@trilead.com\r
  11  * @version $Id: Base64.java,v 1.1 2007/10/15 12:49:56 cplattne Exp $\r
  12  */\r
  13 public class Base64\r
  14 {\r
  15         static final char[] alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();\r
  16         \r
  17         public static char[] encode(byte[] content)\r
  18         {\r
  19                 CharArrayWriter cw = new CharArrayWriter((4 * content.length) / 3);\r
  20 \r
  21                 int idx = 0;\r
  22                                         \r
  23                 int x = 0;\r
  24 \r
  25                 for (int i = 0; i < content.length; i++)\r
  26                 {\r
  27                         if (idx == 0)\r
  28                                 x = (content[i] & 0xff) << 16;\r
  29                         else if (idx == 1)\r
  30                                 x = x | ((content[i] & 0xff) << 8);\r
  31                         else\r
  32                                 x = x | (content[i] & 0xff);\r
  33 \r
  34                         idx++;\r
  35 \r
  36                         if (idx == 3)\r
  37                         {\r
  38                                 cw.write(alphabet[x >> 18]);\r
  39                                 cw.write(alphabet[(x >> 12) & 0x3f]);\r
  40                                 cw.write(alphabet[(x >> 6) & 0x3f]);\r
  41                                 cw.write(alphabet[x & 0x3f]);\r
  42 \r
  43                                 idx = 0;\r
  44                         }\r
  45                 }\r
  46 \r
  47                 if (idx == 1)\r
  48                 {\r
  49                         cw.write(alphabet[x >> 18]);\r
  50                         cw.write(alphabet[(x >> 12) & 0x3f]);\r
  51                         cw.write('=');\r
  52                         cw.write('=');\r
  53                 }\r
  54 \r
  55                 if (idx == 2)\r
  56                 {\r
  57                         cw.write(alphabet[x >> 18]);\r
  58                         cw.write(alphabet[(x >> 12) & 0x3f]);\r
  59                         cw.write(alphabet[(x >> 6) & 0x3f]);\r
  60                         cw.write('=');\r
  61                 }\r
  62 \r
  63                 return cw.toCharArray();\r
  64         }\r
  65 \r
  66         public static byte[] decode(char[] message) throws IOException\r
  67         {\r
  68                 byte buff[] = new byte[4];\r
  69                 byte dest[] = new byte[message.length];\r
  70 \r
  71                 int bpos = 0;\r
  72                 int destpos = 0;\r
  73 \r
  74                 for (int i = 0; i < message.length; i++)\r
  75                 {\r
  76                         int c = message[i];\r
  77 \r
  78                         if ((c == '\n') || (c == '\r') || (c == ' ') || (c == '\t'))\r
  79                                 continue;\r
  80 \r
  81                         if ((c >= 'A') && (c <= 'Z'))\r
  82                         {\r
  83                                 buff[bpos++] = (byte) (c - 'A');\r
  84                         }\r
  85                         else if ((c >= 'a') && (c <= 'z'))\r
  86                         {\r
  87                                 buff[bpos++] = (byte) ((c - 'a') + 26);\r
  88                         }\r
  89                         else if ((c >= '0') && (c <= '9'))\r
  90                         {\r
  91                                 buff[bpos++] = (byte) ((c - '0') + 52);\r
  92                         }\r
  93                         else if (c == '+')\r
  94                         {\r
  95                                 buff[bpos++] = 62;\r
  96                         }\r
  97                         else if (c == '/')\r
  98                         {\r
  99                                 buff[bpos++] = 63;\r
 100                         }\r
 101                         else if (c == '=')\r
 102                         {\r
 103                                 buff[bpos++] = 64;\r
 104                         }\r
 105                         else\r
 106                         {\r
 107                                 throw new IOException("Illegal char in base64 code.");\r
 108                         }\r
 109 \r
 110                         if (bpos == 4)\r
 111                         {\r
 112                                 bpos = 0;\r
 113 \r
 114                                 if (buff[0] == 64)\r
 115                                         break;\r
 116 \r
 117                                 if (buff[1] == 64)\r
 118                                         throw new IOException("Unexpected '=' in base64 code.");\r
 119 \r
 120                                 if (buff[2] == 64)\r
 121                                 {\r
 122                                         int v = (((buff[0] & 0x3f) << 6) | ((buff[1] & 0x3f)));\r
 123                                         dest[destpos++] = (byte) (v >> 4);\r
 124                                         break;\r
 125                                 }\r
 126                                 else if (buff[3] == 64)\r
 127                                 {\r
 128                                         int v = (((buff[0] & 0x3f) << 12) | ((buff[1] & 0x3f) << 6) | ((buff[2] & 0x3f)));\r
 129                                         dest[destpos++] = (byte) (v >> 10);\r
 130                                         dest[destpos++] = (byte) (v >> 2);\r
 131                                         break;\r
 132                                 }\r
 133                                 else\r
 134                                 {\r
 135                                         int v = (((buff[0] & 0x3f) << 18) | ((buff[1] & 0x3f) << 12) | ((buff[2] & 0x3f) << 6) | ((buff[3] & 0x3f)));\r
 136                                         dest[destpos++] = (byte) (v >> 16);\r
 137                                         dest[destpos++] = (byte) (v >> 8);\r
 138                                         dest[destpos++] = (byte) (v);\r
 139                                 }\r
 140                         }\r
 141                 }\r
 142 \r
 143                 byte[] res = new byte[destpos];\r
 144                 System.arraycopy(dest, 0, res, 0, destpos);\r
 145 \r
 146                 return res;\r
 147         }\r
 148 }\r