Steganography for Unicode MK-II

package com.ignatieff.stegotext;

public class Encoder {

	private static char ZERO_SPACE = (char)65279;

	public String encodingString;

	public Encoder(String string){
		encodingString = string;
	}

	public static String encodeString(String plainText, String hiddenMessage){
		Encoder e = new Encoder(plainText);
		return e.encodeString(hiddenMessage);
	}

	private String encodeString(String s){
		if(!canFit(s))return "ERROR: Input string too large.";
		Bits b = new Bits(s);
		System.out.println(b.toString());
		int index = 0;
		StringBuilder r = new StringBuilder();
		while(index<encodingString.length()-b.numZero()){
			r.append(encodingString.charAt(index));
			index++;
		}
		for(int i=0; i<b.bits.length; i++){
			if(b.bits[i]){
				r.append(ZERO_SPACE);
			}else{
				r.append(encodingString.charAt(index));
				index++;
			}
		}
		return r.toString();
	}

	public static String getMessage(String s){
		boolean[] b = new boolean[s.length()];
		for(int i=0; i<s.length(); i++){
			char c = s.charAt(i);
			if(c==ZERO_SPACE)b[i]=true;
		}
		Bits bits = new Bits(b);
		return new Bits(bits.getInt()).getText();
	}

	private boolean canFit(String s){
		if(new Bits(s).numZero()>encodingString.length()+1)return false;
		return true;
	}


}
public class Bits {
	public boolean[] bits;

	public Bits(String s){
		this(s.toCharArray());
	}

	public Bits(char c, int len){
		this(translateChar(c),len);
	}

	public Bits(char[] s){
		Bits b = new Bits();
		for(int i=0; i<s.length; i++){
			b.appendBits(new Bits(s[i],5));
		}
		setEqual(b);
	}

	public int numZero(){
		int r = 0;
		for(int i=0; i<bits.length; i++){
			if(!bits[i])r++;
		}
		return r;
	}

	public static char translateInt(int i){
		switch(i){
			case 0:
				return 'Z';
			case 1:
				return 'Q';
			case 2:
				return '!';
			case 3:
				return 'G';
			case 4:
				return 'J';
			case 5:
				return 'F';
			case 6:
				return '\'';
			case 7:
				return 'U';
			case 8:
				return 'X';
			case 9:
				return 'Y';
			case 10:
				return 'V';
			case 11:
				return 'L';
			case 12:
				return 'K';
			case 13:
				return 'D';
			case 14:
				return 'R';
			case 15:
				return 'E';
			case 16:
				return '?';
			case 17:
				return 'P';
			case 18:
				return ',';
			case 19:
				return '.';
			case 20:
				return '.';
			case 21:
				return 'C';
			case 22:
				return 'S';
			case 23:
				return 'T';
			case 24:
				return 'B';
			case 25:
				return 'W';
			case 26:
				return 'H';
			case 27:
				return 'A';
			case 28:
				return 'N';
			case 29:
				return 'O';
			case 30:
				return 'I';
			case 31:
				return ' ';
		}
		return '#';
	}

	public static int translateChar(char c){
		switch((""+c).toUpperCase().charAt(0)){
			case ' ':
				return 31;
			case 'E':
				return 15;
			case 'T':
				return 23;
			case 'A':
				return 27;
			case 'O':
				return 29;
			case 'I':
				return 30;
			case 'N':
				return 28;
			case 'H':
				return 26;
			case 'S':
				return 22;
			case 'R':
				return 14;
			case 'D':
				return 13;
			case 'L':
				return 11;
			case 'U':
				return 7;
			case 'M':
				return 19;
			case 'C':
				return 21;
			case 'W':
				return 25;
			case 'G':
				return 3;
			case 'F':
				return 5;
			case 'Y':
				return 9;
			case 'P':
				return 17;
			case ',':
				return 18;
			case '.':
				return 20;
			case 'B':
				return 24;
			case 'K':
				return 12;
			case 'V':
				return 10;
			case '\'':
				return 6;
			case '?':
				return 16;
			case 'X':
				return 8;
			case 'J':
				return 4;
			case '!':
				return 2;
			case 'Q':
				return 1;
			case 'Z':
				return 0;
		}
		return -1;
	}

	public Bits(){
		this(0,0);
	}

	public Bits(int num){
		this(num, (int)Math.ceil(log2(num)));
	}

	public Bits(int num, int len){
		bits = new boolean[len];
		for(int i=0; i<len; i++){
			bits[i]=getBit(num,len-(i));
		}
	}

	public Bits(boolean[] bitset){
		bits=bitset;
	}

	private void setEqual(Bits b){
		bits = b.bits;
	}

	public void appendBits(Bits b){
		Bits q = appendBits(this,b);
		setEqual(q);
	}

	public Bits subBit(int beginIndex, int endIndex){
		int beginThis = bits.length-beginIndex-1;
		int dx = endIndex-beginIndex;
		boolean[] b = new boolean[dx];
		for(int i=0; i<dx; i++){
			b[dx-i-1] = bits[beginThis-i];
		}
		return new Bits(b);
	}

	public String getText(){
		if(bits.length%5!=0){return "ERROR: Not a text string.";}
		StringBuilder s = new StringBuilder();
		int b = bits.length/5;
		for(int i=0; i<b; i++){
			Bits sub = subBit(5*i, 5*(i+1));
			s.append(sub.getChar());
		}
		return s.toString();
	}

	public char getChar(){
		if(bits.length>5)return '#';
		return translateInt(getInt());
	}

	public int getInt(){
		int r=0;
		for(int i=0; i<bits.length; i++){
			int d=bits.length-i-1;
			if(bits[d])r+=(int)Math.pow(2, i);
		}
		return r;
	}

	public static Bits appendBits(Bits b1, Bits b2){
		boolean[] b = new boolean[b1.bits.length+b2.bits.length];
		for(int i=0; i<b2.bits.length; i++){
			b[i]=b2.bits[i];
		}
		for(int i=0; i<b1.bits.length; i++){
			b[b2.bits.length+i]=b1.bits[i];
		}
		return new Bits(b);
	}

	public String toString(){
		if(bits.length==0)return "[]";
		StringBuilder s = new StringBuilder();
		s.append("[ ");
		for(int i=0; i<bits.length; i++){
			if(bits[i]){s.append("1");}else{s.append("0");}
			s.append(", ");
		}
		String q = s.toString();
		return q.substring(0,q.length()-2)+" ]";
	}

	private static boolean getBit(int decimal, int N){
		 int constant = 1 << (N-1);
		 return ((decimal & constant)!=0);
	}

	private static double log2(int num){
		return Math.log(num)/Math.log(2);
	}
}