I have a Mac OS X and a flash drive and I would like to store some files as a backup to carry with me in case I completely lose access to my computer (e.g. theft). I would like to encrypt these files. I know close to nothing about how encryption works. It is possible I will need access to these files on another system, OS X or Windows, etc.

How do I encrypt them on one machine so that another one will understand how to decrypt them? (of course, given that I remember the password I used to encrypt them).

I have found solutions like FileVault native to OS X (but I don't know if it will decrypt on another machine) and GPG (which I did not understand that well), I tried using AESCrypt (but it only encrypts file-by-file or a zip archive, which is awkward), I've read that TrueCrypt has been discontinued, etc. What are my options?

  • You could buy a dedicated external drive with encryption built-in – Jonathan Gray Jan 12 '16 at 7:52
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    You could use an encrypted zip file - supported on pretty much any vaguely modern OS, usually with file manager support (e.g. you can open them as folders). – Matthew Jan 12 '16 at 9:52

Unfortunately all the slick methods of Full Disk Encryption are all native to the OS, and so only available on that OS, so if you need cross-platform support you have to use a more nerdy solution like GPG.

In my experience the easiest way to achieve something like this usually ends up, as Matthew suggests, to be an encrypted zip file. You can find plenty of tools to open these on any platform. 7zip is what I usually point people to.

One important point: make sure you always use AES 256 as the encryption method, and not the older native zipCrypto method.

  • Thank you. I've tried GPG, but having to back up keys is kind of a headache. I will try the zip method. – I. S. Jan 12 '16 at 19:29

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