tea.java

俄罗斯方块。适用于初学者学习。想念很好

package xn.tetris;
/**
 * Tea算法
 * 每次操作可以处理8个字节数据
 * KEY为16字节,应为包含4个int型数的int[]，一个int为4个字节
 * 加密解密轮数应为8的倍数，推荐加密轮数为64轮
 * */
public class Tea {
	private final static int[] KEY = new int[]{//加密解密所用的KEY
		0x789f5645, 0xf68bd5a4,
		0x81963ffa, 0x458fac58
	};
	//加密
	public byte[] encrypt(byte[] content, int offset, int[] key, int times){//times为加密轮数
		int[] tempInt = byteToInt(content, offset);
		int y = tempInt[0], z = tempInt[1], sum = 0, i;
		int delta=0x9e3779b9; //这是算法标准给的值
		int a = key[0], b = key[1], c = key[2], d = key[3]; 

		for (i = 0; i < times; i++) {                        
			sum += delta;
			y += ((z<<4) + a) ^ (z + sum) ^ ((z>>5) + b);
			z += ((y<<4) + c) ^ (y + sum) ^ ((y>>5) + d);
		}
		tempInt[0]=y;
		tempInt[1]=z; 
		return intToByte(tempInt, 0);
	}
	//解密
	public byte[] decrypt(byte[] encryptContent, int offset, int[] key, int times){
		int[] tempInt = byteToInt(encryptContent, offset);
		int y = tempInt[0], z = tempInt[1], sum = 0xC6EF3720, i;
		int delta=0x9e3779b9; //这是算法标准给的值
		int a = key[0], b = key[1], c = key[2], d = key[3];
		
		for(i = 0; i < times; i++) { 
			z -= ((y<<4) + c) ^ (y + sum) ^ ((y>>5) + d);
			y -= ((z<<4) + a) ^ (z + sum) ^ ((z>>5) + b);
			sum -= delta; 
		}
		tempInt[0] = y;
		tempInt[1] = z;

		return intToByte(tempInt, 0);
	}
	//byte[]型数据转成int[]型数据
	private int[] byteToInt(byte[] content, int offset){

		int[] result = new int[content.length >> 2];//除以2的n次方 == 右移n位 即 content.length / 4 == content.length >> 2
		for(int i = 0, j = offset; j < content.length; i++, j += 4){
			result[i] = transform(content[j + 3]) | transform(content[j + 2]) << 8 |
			transform(content[j + 1]) << 16 | (int)content[j] << 24;
		}
		return result;
		
	}
	//int[]型数据转成byte[]型数据
	private byte[] intToByte(int[] content, int offset){
		byte[] result = new byte[content.length << 2];//乘以2的n次方 == 左移n位 即 content.length * 4 == content.length << 2
		for(int i = 0, j = offset; j < result.length; i++, j += 4){
			result[j + 3] = (byte)(content[i] & 0xff);
			result[j + 2] = (byte)((content[i] >> 8) & 0xff);
			result[j + 1] = (byte)((content[i] >> 16) & 0xff);
			result[j] = (byte)((content[i] >> 24) & 0xff);
		}
		return result;
	}
	//若某字节为负数则需将其转成无符号正数
	private static int transform(byte temp){
		int tempInt = (int)temp;
		if(tempInt < 0){
			tempInt += 256;
		}
		return tempInt;
	}
	
	/*public static void main(String[] args){
		
		int[] KEY = new int[]{//加密解密所用的KEY
				0x789f5645, 0xf68bd5a4,
				0x81963ffa, 0x458fac58
			};
		Tea tea = new Tea();
		
		byte[] info = new byte[]{
				
				1,2,3,4,5,6,7,8
		};
		System.out.print("原数据：");
		for(byte i : info)
			System.out.print(i + " ");
		System.out.println();
		
		byte[] secretInfo = tea.encrypt(info, 0, KEY, 32);
		System.out.print("加密后的数据：");
		for(byte i : secretInfo)
			System.out.print(i + " ");
		System.out.println();
		
		byte[] decryptInfo = tea.decrypt(secretInfo, 0, KEY, 32);
		System.out.print("解密后的数据：");
		for(byte i : decryptInfo)
			System.out.print(i + " ");
		
	}*/
	
}