I'd like to be able to send people encrypted messages (given I have their public keys which they might give me in a number of ways), when I'm travelling, and don't have a laptop with me but do have a USB that I may have to use on a Mac, Linux or Windows computer wherever I go.

Now for both security and privacy reasons, I don't trust using online web-hosted PGP encrypt / decrypt tools for this purpose, even if their JavaScript code does all the crypto crunching locally in the browser and they promise that they can't see any of the text in the box themselves.

So what would be a reliable, open-source, portable app, (no third-party libraries required on the machine [such as Java], just plug and play), for each of the three main platforms (and ideally the same app from the same project), to do this?


2 Answers 2


GnuPG or GNU Privacy Guard is available for all the main desktop OSs and even Android there is a Portable version for use on windows machines without installation: Either by downloading from here installing then and running mkportable.exe or as gpg4usb.

Keep in mind that if you loose a USB key with your keys on you have to regard them as compromised.

Are you sure about using someone else's computer running their OS with any additions, viruses or otherwise to encrypt your data? You might be better of creating a boot-able Linux installation on a USB key and booting from that before doing any encryption, mail, etc.,

  • 1
    Well, the problem is that it's too much of an intrusion to ask people to restart their computers (close off everything they're doing) just so I can send someone an email for five minutes. Risking malware on other people's systems is just something I decided I'll have to accept. However, perhaps I should have a second USB with bootable linux on it for the times I can do it. Still, I will need working portable PGP apps for all three platforms, for the times I can't. Ok so GnuPG: Win, check. Linux: can it run portable? Mac: is the .app portable? I may have to 'simply try' and get back to you :).
    – user2716
    Jan 14, 2015 at 21:54

I wouldn't trust my GnuPG private keys to any operating system I'm not controlling. So my recommendation for this case is to use the Tails Linux Live CD.

Another promising multi-architecture set of tools is p≡p – pretty Easy privacy which seems to plan to have some portable variants of their tools and plugins.

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