I am looking for a encryption which would allow me to use 8 secret bytes as the key to generate 8 encrypted bytes back.

I have been browsing on google and this site, but most encryptions I come across output much more than 8 bytes.

I am using delphi for this project and stubbled across:
http://www.efg2.com/Lab/Library/Delphi/MathFunctions/Cryptography.htm

but I am totaly lost at which one I could use.

Any help is always appreciated.

DES should have an effective mmh...54? BITkey, out of a 64 BIT (8 byte) one.
It should be fine for you.
With such short key, don't hope to make a safe cipher, but..
--edit-----
I wrote Byte instead of BIT, sorry!

Why don't you just randomly select 8 bytes of the output?

Err, maybe because he'd like to decrypt it again?

Anyway, blowfish would be a good alternative for you markh51.

Ok, guys... thanks for the comments.

dELTA has good a good point

I see... I thought he was just trying to generate a hash.

I'm working on some blowfish code right now. I like it alot.

REALLY fast once you have the subkeys generated. Uncrackable. Simple as pie to code. etc etc Pretty easy to modify too,