It's not advisable to use MD5 for anything. It's security is severely compromise...

It's not advisable to use MD5 for anything. It's security is severely compromised. Weaknesses in MD5 have already been exploited to create a fake root CA[1] and a fake Microsoft code-signing certificate[2]. There isn't practical publicly-known preimage attack, but there was a theoretical attack published in 2009[3]. Additionally, MD5 can be calculated far too quickly to use for password hashing. A commodity GPU from 2009 can calculate 200 million MD5 hashes per second [4]. For password hashing you should use something like bcrypt or scrypt which is specifically designed to be computationally expensive.