Base64.as

package {

        import flash.utils.ByteArray;
        
        public class Base64 {
                
                private static const BASE64_CHARS:String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

                public static function encodeByteArray(data:ByteArray):String {
                        // Initialise output
                        var output:String = "";
                        
                        // Create data and output buffers
                        var dataBuffer:Array;
                        var outputBuffer:Array = new Array(4);
                        
                        // Rewind ByteArray
                        data.position = 0;
                        
                        // while there are still bytes to be processed
                        while (data.bytesAvailable > 0) {
                                // Create new data buffer and populate next 3 bytes from data
                                dataBuffer = new Array();
                                for (var i:uint = 0; i < 3 && data.bytesAvailable > 0; i++) {
                                        dataBuffer[i] = data.readUnsignedByte();
                                }
                                
                                // Convert to data buffer Base64 character positions and 
                                // store in output buffer
                                outputBuffer[0] = (dataBuffer[0] & 0xfc) >> 2;
                                outputBuffer[1] = ((dataBuffer[0] & 0x03) << 4) | ((dataBuffer[1]) >> 4);
                                outputBuffer[2] = ((dataBuffer[1] & 0x0f) << 2) | ((dataBuffer[2]) >> 6);
                                outputBuffer[3] = dataBuffer[2] & 0x3f;
                                
                                // If data buffer was short (i.e not 3 characters) then set
                                // end character indexes in data buffer to index of '=' symbol.
                                // This is necessary because Base64 data is always a multiple of
                                // 4 bytes and is basses with '=' symbols.
                                for (var j:uint = dataBuffer.length; j < 3; j++) {
                                        outputBuffer[j + 1] = 64;
                                }
                                
                                // Loop through output buffer and add Base64 characters to 
                                // encoded data string for each character.
                                for (var k:uint = 0; k < outputBuffer.length; k++) {
                                        output += BASE64_CHARS.charAt(outputBuffer[k]);
                                }
                        }
                        
                        // Return encoded data
                        return output;
                }
        }
}