Function Udecrypt_byte

src/Setup/unzip.cpp:2213–2216

  keys[2] = CRC32(keys[2], keys[1] >> 24);
}
char Udecrypt_byte(unsigned long *keys)
{ unsigned temp = ((unsigned)keys[2] & 0xffff) | 2;
  return (char)(((temp * (temp ^ 1)) >> 8) & 0xff);
}
char zdecode(unsigned long *keys, char c)
{ c^=Udecrypt_byte(keys);
  Uupdate_keys(keys,c);