how to write back to an existing file, ensuring the bits on the disk get overwritten in OS X

Question

What API's Cocoa or Core Foundation, can I use to make sure that when I write back to a file that already exists on the storage device, that the bits get written over? The idea is to clear out the bits for security reasons.

Answer 1

No such API exists. It would be much better to only store properly encrypted data on disk if you are worried about security.