js/encoding/ASN1/base64.js

// Base64 JavaScript decoder
// Copyright (c) 2008 Lapo Luchini <lapo@lapo.it>

// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
// 
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

Base64 = {};

Base64.decode = function(a) {
    if (Base64.decoder == undefined) {
        var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
        var allow = "= \f\n\r\t\u00A0\u2028\u2029";
        var dec = [];
        for (var i = 0; i < 64; ++i)
            dec[b64.charAt(i)] = i;
        for (var i = 0; i < allow.length; ++i)
            dec[allow.charAt(i)] = -1;
        Base64.decoder = dec;
    }
    var out = [];
    var bits = 0, char_count = 0;
    for (var i = 0; i < a.length; ++i) {
        var c = a.charAt(i);
        if (c == '=')
            break;
        c = Base64.decoder[c];
        if (c == -1)
            continue;
        if (c == undefined)
            throw 'Illegal character at offset ' + i;
        bits |= c;
        if (++char_count >= 4) {
            out[out.length] = (bits >> 16);
            out[out.length] = (bits >> 8) & 0xFF;
            out[out.length] = bits & 0xFF;
            bits = 0;
            char_count = 0;
        } else {
            bits <<= 6;
        }
    }
    switch (char_count) {
      case 1:
        throw "Base64 encoding incomplete: at least 2 bits missing";
        break;
      case 2:
        out[out.length] = (bits >> 10);
        break;
      case 3:
        out[out.length] = (bits >> 16);
        out[out.length] = (bits >> 8) & 0xFF;
        break;
    }
    return out;
}

Base64.re = /-----BEGIN [^-]+-----([A-Za-z0-9+\/=\s]+)-----END [^-]+-----|begin-base64[^\n]+\n([A-Za-z0-9+\/=\s]+)====/;
Base64.unarmor = function(a) {
    var m = Base64.re.exec(a);
    if (m) {
        if (m[1])
            a = m[1];
        else if (m[2])
            a = m[2];
        else
            throw "RegExp out of sync";
    }
    return Base64.decode(a);
}