The java version is using TripleDES encryption in CBC mode with PKCS5 padding. From what I've read and seen on the web, mcrypt with PHP does not support PKCS5 padding.

I know beginners often screw up encryption, and I'm certainly a beginner so I'd like some feedback on my approach.I wrote a small PHP app to store passwords in a database for a group of sys admins ...

One use for symmetric encryption is an encrypted file system. Since modern computers can perform complex calculations easily and quickly, they have the ability to encrypt and decrypt data on demand.