decrypt

void decrypt(unsigned char *in, unsigned char *out, int len) {
    int i;
    out[len ] = 0;
    for (i = len - 1; i > 0; i--) {
        out[i] = (((((in[i] ^ in[i - 1]) + 16) ^ 0xA5)- 16) ^0xCA);
    }
}