I\'ve just landed a PHP5 gig. I won\'t be handling the parts of the application that involve super sensitive data, but I still know embarrassingly little about security and encr
If you're looking at it from a PHP context, I'd recommend this book:
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Pro PHP Security on Amazon
The thing I really like about this book is it covers much more than just a list of the security-related functions in PHP. A large part of it covers general web security concepts and protection mechanisms. Permissions, principle of least privilege, encryption, hashing, cross-site scripting, cross-site request forgeries, session hijacking, etc. are all covered here, with examples of writing secure code in PHP.
Having taken graduate-level security classes in college, I'm impressed with the coverage in this book. I'd consider it required reading for any professional PHP developer.