Decode Base64 and save as binary file

Question

Hi there,
I am using Adobe Air 1.5 with JavaScript and want to save a file to my hard
drive. I get the data from a WebService via SOAP as a Base64 encoded string. A test-string is attached. When I try to decode it with
the WebKit function "atob()" and try to save this bytes with following code, I can't open the file.
this.writeFile = function(outputfile, content, append){
var file =a ir.File.applicationStorageDirectory.resolvePath(outputfile);
var stream = newa ir.FileStream();
if (append) {
stream.open(filea, ir.FileMode.APPEND);
}else {
stream.open(filea, ir.FileMode.WRITE);
try{//Binärdaten
stream.writeBytes(content0, , content.length);
}catch(e){//Textdaten
stream.writeUTFBytes(content);
stream.close();
The same happens when I try to open a file from my HDD and read in the bytes. When I decode it to base64, the string is not equal to the string, which is correct.
I attached a working Base64 string, which I could convert back to a zip-file via a only encoder.
So my question is, how can I decode a Base64 string and save the binary data to a file?
Thank you for your help.

Answer 1

I rewrote the Base64 decoder/encoder to use it with a ByteArray. Here ist the code:
var byteArrayToBase64 = function(byteArr){
    var base64s = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
     var encOut = "";
    var bits;
    var i = 0;
    while(byteArr.length >= i+3){
        bits = (byteArr[i++] & 0xff) << 16 | (byteArr[i++] & 0xff) << 8 | byteArr[i++] & 0xff;
          encOut += base64s.charAt((bits & 0x00fc0000) >> 18) + base64s.charAt((bits & 0x0003f000) >> 12) + base64s.charAt((bits & 0x00000fc0) >> 6) + base64s.charAt((bits & 0x0000003f));
    if(byteArr.length-i > 0 && byteArr.length-i < 3){
        var dual = Boolean(byteArr.length - i - 1);
        bits = ((byteArr[i++] & 0xff) << 16) | (dual ? (byteArr[i] & 0xff) << 8 : 0);
        encOut += base64s.charAt((bits & 0x00fc0000) >> 18) + base64s.charAt((bits & 0x0003f000) >> 12) + (dual ? base64s.charAt((bits & 0x00000fc0) >> 6) : '=') + '=';
    return encOut;
var base64ToByteArray = function(encStr){
    var base64s = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
     var decOut = new air.ByteArray(); 
    var bits;
    for(var i = 0, j = 0; i<encStr.length; i += 4, j += 3){
        bits = (base64s.indexOf(encStr.charAt(i)) & 0xff) <<18 | (base64s.indexOf(encStr.charAt(i +1)) & 0xff) <<12 | (base64s.indexOf(encStr.charAt(i +2)) & 0xff) << 6 | base64s.indexOf(encStr.charAt(i +3)) & 0xff;
        decOut[j+0] = ((bits & 0xff0000) >> 16);
          if(i+4 != encStr.length || encStr.charCodeAt(encStr.length - 2) != 61){
               decOut[j+1] = ((bits & 0xff00) >> 8);
          if(i+4 != encStr.length || encStr.charCodeAt(encStr.length - 1) != 61){
               decOut[j+2] = (bits & 0xff);
    return decOut;