Simple encryption in java-no key/password

Say I have an IP address, 192.168.1.1

I want my program to create a random one-word string based on this IP address which can be easily decrypted without a key or password or additional security.

eg.

I enter 192.168.1.1

Program converts it to AzlQrEHCSD or some other random string

I enter this string in the program

It gets converted back to 192.168.1.1

Is there any simple algorithm that can do this without generating stuff like keys or additional passwords? I understand that keys and passwords are a must for encryption and decryption, but my scenario does not require it.