src/org/ibex/crypto/Base64.java

   1 package org.ibex.crypto;
   2
   3 import java.io.UnsupportedEncodingException;
   4
   5 public final class Base64 {
   6         private Base64() { /* can't be instansiated */ }
   7
   8     private static final char encodeMap[] = {
   9         'A','B','C','D','E','F','G','H',
  10         'I','J','K','L','M','N','O','P',
  11         'Q','R','S','T','U','V','W','X',
  12         'Y','Z','a','b','c','d','e','f',
  13         'g','h','i','j','k','l','m','n',
  14         'o','p','q','r','s','t','u','v',
  15         'w','x','y','z','0','1','2','3',
  16         '4','5','6','7','8','9','+','/'
  17     };
  18
  19     private static final int decodeMap[] = {
  20         -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
  21         -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
  22         -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,62,-1,-1,-1,63,
  23         52,53,54,55,56,57,58,59,60,61,-1,-1,-1,-2,-1,-1,
  24         -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,
  25         15,16,17,18,19,20,21,22,23,24,25,-1,-1,-1,-1,-1,
  26         -1,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,
  27         41,42,43,44,45,46,47,48,49,50,51,-1,-1,-1,-1,-1
  28     };
  29
  30         public static void main(String[] args){
  31         if(args.length == 2 && args[0].equals("encode"))
  32             System.out.println(encode(args[1].getBytes()));
  33         else if(args.length == 2 && args[0].equals("decode"))
  34             System.out.println(new String(decode(args[1])));
  35         else {
  36             System.out.println("Usage: Base64 {encode,decode} text");
  37             System.exit(1);
  38         }
  39         System.exit(0);
  40         }
  41
  42         public static byte[] decode(String inString){
  43         char[] in = inString.toCharArray();
  44         int part=0;
  45         int theBytes = 0;
  46         byte[] out = new byte[in.length / 4 * 3];
  47         int outPos = 0;
  48         for(int i=0;i<in.length;i++){
  49             int x = decodeMap[in[i] & 0x7f];
  50             if(x == -1) continue;
  51             if(x == -2) break;
  52             theBytes = (theBytes << 6) | x;
  53             part++;
  54             if(part == 4){
  55                 part = 0;
  56                 out[outPos++] = (byte)((theBytes >>> 16) & 0xff);
  57                 out[outPos++] = (byte)((theBytes >>>  8) & 0xff);
  58                 out[outPos++] = (byte)((theBytes >>>  0) & 0xff);
  59             }
  60         }
  61         switch(part){
  62             case 3:
  63                 out[outPos++] = (byte)((theBytes >>> 10) & 0xff);
  64                 out[outPos++] = (byte)((theBytes >>> 2) & 0xff);
  65                 break;
  66             case 2:
  67                 out[outPos++] = (byte)((theBytes >> 4) & 0xff);
  68                 break;
  69         }
  70
  71         if(outPos < out.length){
  72             byte[] a = new byte[outPos];
  73             System.arraycopy(out,0,a,0,outPos);
  74             return a;
  75         } else {
  76             return out;
  77         }
  78     }
  79
  80         public static String encode(String in) { return encode(getBytes(in)); }
  81     public static String encode(byte[] in){
  82         int part=0;
  83         int theBytes = 0;
  84         char[] out = new char[(in.length / 3 + 1) * 4];
  85         int outPos = 0;
  86         for(int i=0;i<in.length;i++){
  87             theBytes = (theBytes << 8) | in[i];
  88             part++;
  89             if(part == 3){
  90                 part = 0;
  91                 out[outPos++] = encodeMap[(theBytes >>> 18) & 0x3f];
  92                 out[outPos++] = encodeMap[(theBytes >>> 12) & 0x3f];
  93                 out[outPos++] = encodeMap[(theBytes >>>  6) & 0x3f];
  94                 out[outPos++] = encodeMap[(theBytes >>>  0) & 0x3f];
  95             }
  96         }
  97         switch(part){
  98             case 2:
  99                 out[outPos++] = encodeMap[(theBytes >>>  10) & 0x3f];
 100                 out[outPos++] = encodeMap[(theBytes >>>  4)  & 0x3f];
 101                 out[outPos++] = encodeMap[(theBytes <<   2)  & 0x3f];
 102                 out[outPos++] = '=';
 103                 break;
 104             case 1:
 105                 out[outPos++] = encodeMap[(theBytes >>> 2) & 0x3f];
 106                 out[outPos++] = encodeMap[(theBytes <<  4) & 0x3f];
 107                 out[outPos++] = '=';
 108                 out[outPos++] = '=';
 109                 break;
 110         }
 111         return new String(out,0,outPos);
 112     }
 113
 114     public static byte[] getBytes(String s) {
 115         try {
 116                 return s.getBytes("US-ASCII");
 117         } catch (UnsupportedEncodingException e) {
 118                 throw new Error("should never happen");
 119         }
 120     }
 121 }