public class Test {
public static void encode(byte[] in, byte[] out, int password) {
int len = in.length;
// : a^b^b = a
int seed = password ^ 0x8c357ca5;
for (int i = 0; i < len; ++i) {
byte a = (byte) ((in[i] ^ seed) >>> 5);// byte 3 , 3
byte b = (byte) (((((int) in[i]) << 16) ^ seed) >>> (16 - 3));// 5 5
a &= 0x7; // 3
b &= 0xf8; // 5
out[i] = (byte) (a | b); //
seed = (seed * 3687989 ^ seed ^ in[i]); // IN, OUT,
}
}
//
public static void decode(byte[] in, byte[] out, int password) {
int len = in.length;
int seed = password ^ 0x8c357ca5;
for (int i = 0; i < len; ++i) {
byte a = (byte) (((in[i]&0x7) <<5) ^seed); // 3 5 ,
byte b = (byte) ((((((int) in[i])&0xf8) << 13) ^ seed) >>> 16); // 5 ,13 , 5
a &= 0xe0;// 3
b &= 0x1f;// 5
out[i] = (byte) (a | b);
seed = (seed * 3687989 ^ seed ^ out[i]);// OUT
}
}
public static void main(String[] args) throws Exception {
int password = 0xe87dd9d3;
byte[] buf1 = { 29, -16, 96, 43, -85, 25, -96, 83, 13, 66, -109, 49, -111, 0, 60, -101, 99, -86, -38, 86, -35,
48, 23, 83, -102, 25, 73, -116, -101, -88, -5, 14, -14, -112, 87, -87, 2, 108, -58, 40, 56, 12, 108,
77, 83, 38, 20, -114, };
byte[] buf2 = new byte[buf1.length];
decode(buf1, buf2, password);
System.out.println(new String(buf2, "GBK"));
}
}
は主に(1):復号は暗号化の逆過程である(2):a^b^b=a