I'm searching for a encrypt method that receives an int variable and outputs exactly 11 hexadecimal digits.
I'm starting on a existing application, that already has a database of more than 130.000 registers, each one with his own 11 hex-digits code. The old algorhythm only generated random 11 hex-digits, with no information codified. The new algorhythm should encrypt the id of a table (int data type, 4 bytes) into a 11 hex-dig. In case of collisions (with old registers, that should be kept), I'm thinking of using a counter as "salt", combine it with the id I want to encrypt, and repeat incrementing the counter until it does not collide.
I have searched a lot these days about encrypt methods, symmetric and assymmetric methods, but all of them gives a result bigger than my limitation of 44 bits/11 hex-digits. I've also found that a so short cyphertext is not secure, but these data are not so critical and I can't change this limitation of the application, so it's fine.
Because I need to validate these codes in the future (check if decrypted id is present on table, when datetime information indicates that it's a new-algorhythm code), I cannot take only a part of the cyphertext (for example, using something like "LEFT(code, 11)").
The application runs on PHP/MySQL. Is there a encryption method that parametrizes the length of output? Or should I develop a custom encryption? In this case, any suggestion for avoiding collisions?
Thanks in advance.
