I want to do something like

So I the actual SSN's are not shown on my screen, but the MD5 hashes are shown. In other words, I want the SSN to be hashed.

How can I do this in DB2? If there is no built in function, how can I create one?

Please note that I don't have many permissions, and I prefer something I can do on my own. However, if it's really impossible, I can ask the DB admin to enable features.

If you didn't stick to MD5 algorithm, you can use ENCRYPT built-in function.

IBM DB2 9.7 for Linux, UNIX, and Windows
Version 9 Release 7
SQL Reference, Volume 1

Hash Function

Thank you! It worked after I executed the SET ENCRYPTION PASSWORD command.

I found that when I was searching the forum (before asking this question) but I don't have create function permission

Beware that hashing (like md5) and encrypting are not similar things!

In order to encrypt, you need a password, which will allow you to decrypt later on.
This means that someone in the possession of the password (e.g., the DBA, or the program that does the encryption) can recover the original SSN.

Hashing, on the other hand, is a one-way function: no password is needed to "mangle" the data, but there exists no "unmangle" function, so there is a guarantee that no-one will be able to recover the SSN from its hashed value.

Frankly, I don't see any reason for displaying hashed or encrypted SSNs. If you don't want to show them, don't show them. I mean, at all. Why showing seemingly random characters instead?