1 // Base64 encoder/decoder - pulled from http://ostermiller.org/calc/encode.html. Licensed under the GPL.

     2 

     3 var END_OF_INPUT = -1;

     4 

     5 var base64Chars = new Array(

     6     'A','B','C','D','E','F','G','H',

     7     'I','J','K','L','M','N','O','P',

     8     'Q','R','S','T','U','V','W','X',

     9     'Y','Z','a','b','c','d','e','f',

    10     'g','h','i','j','k','l','m','n',

    11     'o','p','q','r','s','t','u','v',

    12     'w','x','y','z','0','1','2','3',

    13     '4','5','6','7','8','9','+','/'

    14 );

    15 

    16 var reverseBase64Chars = new Array();

    17 for (var i=0; i < base64Chars.length; i++){

    18     reverseBase64Chars[base64Chars[i]] = i;

    19 }

    20 

    21 var base64Str;

    22 var base64Count;

    23 

    24 function setBase64Str(str){

    25     base64Str = str;

    26     base64Count = 0;

    27 }

    28 function readBase64(){    

    29     if (!base64Str) return END_OF_INPUT;

    30     if (base64Count >= base64Str.length) return END_OF_INPUT;

    31     var c = base64Str.charCodeAt(base64Count) & 0xff;

    32     base64Count++;

    33     return c;

    34 }

    35 function encodeBase64(str){

    36     setBase64Str(str);

    37     var result = '';

    38     var inBuffer = new Array(3);

    39     var lineCount = 0;

    40     var done = false;

    41     while (!done && (inBuffer[0] = readBase64()) != END_OF_INPUT){

    42         inBuffer[1] = readBase64();

    43         inBuffer[2] = readBase64();

    44         result += (base64Chars[ inBuffer[0] >> 2 ]);

    45         if (inBuffer[1] != END_OF_INPUT){

    46             result += (base64Chars [(( inBuffer[0] << 4 ) & 0x30) | (inBuffer[1] >> 4) ]);

    47             if (inBuffer[2] != END_OF_INPUT){

    48                 result += (base64Chars [((inBuffer[1] << 2) & 0x3c) | (inBuffer[2] >> 6) ]);

    49                 result += (base64Chars [inBuffer[2] & 0x3F]);

    50             } else {

    51                 result += (base64Chars [((inBuffer[1] << 2) & 0x3c)]);

    52                 result += ('=');

    53                 done = true;

    54             }

    55         } else {

    56             result += (base64Chars [(( inBuffer[0] << 4 ) & 0x30)]);

    57             result += ('=');

    58             result += ('=');

    59             done = true;

    60         }

    61         lineCount += 4;

    62         if (lineCount >= 76){

    63             result += ('\n');

    64             lineCount = 0;

    65         }

    66     }

    67     return result;

    68 }

    69 function readReverseBase64(){   

    70     if (!base64Str) return END_OF_INPUT;

    71     while (true){      

    72         if (base64Count >= base64Str.length) return END_OF_INPUT;

    73         var nextCharacter = base64Str.charAt(base64Count);

    74         base64Count++;

    75         if (reverseBase64Chars[nextCharacter]){

    76             return reverseBase64Chars[nextCharacter];

    77         }

    78         if (nextCharacter == 'A') return 0;

    79     }

    80     return END_OF_INPUT;

    81 }

    82 

    83 function ntos(n){

    84     n=n.toString(16);

    85     if (n.length == 1) n="0"+n;

    86     n="%"+n;

    87     return unescape(n);

    88 }

    89 

    90 function decodeBase64(str){

    91     setBase64Str(str);

    92     var result = "";

    93     var inBuffer = new Array(4);

    94     var done = false;

    95     while (!done && (inBuffer[0] = readReverseBase64()) != END_OF_INPUT

    96         && (inBuffer[1] = readReverseBase64()) != END_OF_INPUT){

    97         inBuffer[2] = readReverseBase64();

    98         inBuffer[3] = readReverseBase64();

    99         result += ntos((((inBuffer[0] << 2) & 0xff)| inBuffer[1] >> 4));

   100         if (inBuffer[2] != END_OF_INPUT){

   101             result +=  ntos((((inBuffer[1] << 4) & 0xff)| inBuffer[2] >> 2));

   102             if (inBuffer[3] != END_OF_INPUT){

   103                 result +=  ntos((((inBuffer[2] << 6)  & 0xff) | inBuffer[3]));

   104             } else {

   105                 done = true;

   106             }

   107         } else {

   108             done = true;

   109         }

   110     }

   111     return result;

   112 }

   113