I dont think access does that. You got to do that from your Client-side. There are many such logics. You can create your own.
http://www.softcircuits.com/sw_vbsrc.htm - scroll down to get the sample code for encryption and decryption algorithm there. It is VB5 code.
You can search on google too on this. You will find a lots of results there.
Cheers!
-Vijay G