import java.io.*;

public class Base64 {

    /**
     *  Decodes BASE64 encoded string.
     *  @param encoded string
     *  @return decoded data as byte array
     */
    public static byte[] decode(String encoded)  {
        int i;
    	byte output[] = new byte[3];
    	int state;

		ByteArrayOutputStream data = new ByteArrayOutputStream(encoded.length());

    	state = 1;
    	for(i=0; i < encoded.length(); i++)
    	{
            byte c;
            {
            	char alpha = encoded.charAt(i);
            	if (Character.isWhitespace(alpha)) continue;

		   		if ((alpha >= 'A') && (alpha <= 'Z')) c = (byte)(alpha - 'A');
		   		else if ((alpha >= 'a') && (alpha <= 'z')) c = (byte)(26 + (alpha - 'a'));
				else if ((alpha >= '0') && (alpha <= '9')) c = (byte)(52 + (alpha - '0'));
			   	else if (alpha=='+') c = 62;
		   		else if (alpha=='/') c = 63;
			   	else if (alpha=='=') break; // end
		   		else return null; // error
            }

            switch(state)
            {   case 1: output[0] = (byte)(c << 2);
                        break;
                case 2: output[0] |= (byte)(c >>> 4);
                        output[1] = (byte)((c & 0x0F) << 4);
                        break;
                case 3: output[1] |= (byte)(c >>> 2);
                        output[2] =  (byte)((c & 0x03) << 6);
                        break;
                case 4: output[2] |= c;
                        data.write(output,0,output.length);
                        break;
            }
            state = (state < 4 ? state+1 : 1);
    	} // for

	if (i < encoded.length()) /* then '=' found, but the end of string */
            switch(state)
            {   case 3:
            		data.write(output,0,1);
                    return (encoded.charAt(i)=='=') && (encoded.charAt(i+1)=='=')
                    	 ? data.toByteArray() : null;
            	case 4:
            		data.write(output,0,2);
                    return (encoded.charAt(i)=='=') ? data.toByteArray() : null;
            	default: return null;
            }
    	else return (state==1 ? data.toByteArray() : null); /* end of string */

    } // decode

    private final static String base64 =
		"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

    /**
     *  Encodes binary data by BASE64 method.
     *  @param data binary data as byte array
     *  @return encoded data as String
     */
    public static String encode(byte[] data) {

	char output[] = new char[4];
	int state = 1;
	int restbits = 0;
        int chunks = 0;

	StringBuffer encoded = new StringBuffer();

    	for(int i=0; i < data.length; i++)
    	{
            int ic = (data[i] >= 0 ? data[i] : (data[i] & 0x7F) + 128);
            switch (state)
            {	case 1:
            	 	 output[0] = base64.charAt(ic >>> 2);
                     restbits = ic & 0x03;
                     break;
             	case 2:
             		 output[1] = base64.charAt((restbits << 4) | (ic >>> 4));
                     restbits = ic & 0x0F;
                     break;
             	case 3:
             		 output[2] = base64.charAt((restbits << 2) | (ic >>> 6));
                     output[3] = base64.charAt(ic & 0x3F);
                     encoded.append(output);

                     // keep no more the 76 character per line
                     chunks++;
                     if ((chunks % 19)==0) encoded.append("\r\n");
                     break;
            }
            state = (state < 3 ? state+1 : 1);
    	} // for

    	/* final */
    	switch (state)
    	{    case 2:
             	 output[1] = base64.charAt((restbits << 4));
                 output[2] = output[3] = '=';
                 encoded.append(output);
                 break;
             case 3:
             	 output[2] = base64.charAt((restbits << 2));
                 output[3] = '=';
		 encoded.append(output);
                 break;
    	}

	return encoded.toString();
    } // encode()

} // Base64