Password protect/encrypt USB drive readable on both Mac and Win?
May 11, 2015 10:03 PM   Subscribe

I use Macs. I use a flash drive to carry powerpoint presentations and other documents that I need to access on PC's running various flavours of Windows, which are not mine and I will not have administrator access to. Is there a way that I can protect/encrypt the drive in a way that will let me use it on both systems, without having to pre-install software on the Windows system? I do not need government-grade encryption, just something that will stop casual snoopers accessing the data if I lose the drive.
posted by modernnomad to Computers & Internet (6 answers total) 1 user marked this as a favorite
Is there a way that I can protect/encrypt the drive in a way that will let me use it on both systems, without having to pre-install software on the Windows system?

BitLocker is the Windows-native thing and there's no Mac implementation.

First thought is FAT32+TrueCrypt volume, but I say that with slightly gritted teeth. (TrueCrypt development stopped abruptly, and the last version had security warnings, but the audit was just completed and there don't appear to be backdoors.)

You could put the Windows TrueCrypt executable on a separate flash drive: there's a standalone/traveller install option. You could install it on the same drive if you don't mind tipping off people who might find it what the other contents are, since they won't be able to open the volume without a passphrase. You could also try one of the TrueCrypt forks like VeraCrypt, which is cross-platform.
posted by holgate at 10:22 PM on May 11, 2015 [1 favorite]

I think the best method is probably to partition the drive into two parts: a small FAT16 or FAT32 part, and a bigger part holding a raw Truecrypt volume. On the FAT part, you can put Truecrypt as a directly-runnable Windows executable.

Truecrypt is still the best option for cross-platform disk encryption, and as far as anyone can ascertain the weird way that development stopped doesn't suggest anything bad about the software itself, but probably some sort of weird interpersonal issues among the (anonymous) development team.
posted by Kadin2048 at 10:28 PM on May 11, 2015 [2 favorites]

It doesn't sound to me like you need filesystem-level encryption, you just need to protect the contents of a finite number of presentation files. You should be able to put a decent command-line encryption utility on the flash drive along with the data files and use it when necessary.

It may be slightly less convenient and the learning curve steeper but you'll have a greater selection of cross-platform options and you can have some confidence that you won't be needing admin rights on the machines you are using to display.

Do remember, though, that when you have either the decrypted document or the cybertext plus key on a machine that you do not administer you should assume your document's contents are no longer safe from the owner of that machine -- when you use someone else's machine all sorts of things can happen. So yes, you'll be reasonably protected against the "I dropped the memory stick in the parking lot and am worried someone might read it" problem but not against much more than that.
posted by Nerd of the North at 10:48 PM on May 11, 2015 [4 favorites]

An encrypted ZIP archive might work, but I'm not sure if Windows machines typically have a ZIP utility already installed.
posted by Johnny Wallflower at 11:20 PM on May 11, 2015

GnuPG if you prefer file-only encryption like Nerd of the North suggested. Here's a portable version for Windows, and here's a Mac version.
Note that you can use GnuPG symmetrically (ie, with a password) if assymmetric encryption (public/private key pair) seems too complicated. You can even combine both modes, making the files decryptable either by a password of your choosing or by having your private key available.

The disadvantage of file encryption is that you have to encrypt one file at a time, unless you tar/zip them all together first (which would mean another cross-platform utility would be needed for doing that).

If you typically carry a bunch of files, full-disk encryption might be simpler to use. In that case, TrueCrypt is the way to go for cross-platform compatibility though I'm not sure if it can be run without admin privileges.
posted by Bangaioh at 9:18 AM on May 12, 2015

If they are Microsoft Office files, the inbuilt encryption will deter the casually nosy types. You needn't install any additional software, but you would have to deal with unlocking them (or providing the password) so others could view them.
posted by ostranenie at 5:23 PM on May 12, 2015

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