I get requests from non-technical people in my life for how they can email sensitive files (to other non-technical users) in a way that is especially secure. My refrain: “Technically there is, but… (contemplates PGP for half a second)… it’s very complicated to setup.”

Between email phishing attacks, Dropbox and everyone else on HIBP, I honestly don’t know what advice to give non-technical users besides put it on a USB drive and drop it off. I can think of security pitfalls with literally any other file transmission technology that is easily accessible to non-technical users. If anyone has a suggestion I’m all ears.

In the situation where you want to distribute a sensitive file without a trusted third party of any kind of key infrastructure in place, it's probably easier to not bother with public key encryption. Which isn't too bad:

  gpg -c secretfile.zip

Not sure it can get much easier? To decrypt:

  gpg secretfile.zip.gpg

The point is that gpg is a tool that most people either already have or can install in a trusted way without downloading binaries from public web pages. Even more common to have installed is openssl:

  openssl enc -aes256 -in secretfile.zip -out secretfile.zip.enc
  openssl enc -d -aes256 -in secretfile.zip.enc -out secretfile.zip

Using these tools are perfectly secure for all practical attacks. The hard part is transmitting the password over a secure channel.

Public key encryption is even more useful, but requires a little more knowledge on the end user's part on key pairs, signing keys, publishing them etc. Should an end user just wish to transmit an encrypted file then symmetric encryption is easier to understand.

Never use the OpenSSL CLI to encrypt things. It creates unauthenticated ciphertext. It is anything but "perfectly secure".

I don't think it's even the case that the OpenSSL project wants you to be using their code this way. It's just that Unix nerds (hey: it me) find things like this and adopt them, then write things about how they're "perfectly secure" in message board slapfights. It's a microcosm of the whole problem.

Given the use case here, where someone wants to send a single file to someone else, with no pre-existing way to communicate securely, why would it matter? The only practical attacks would be on the passphrase itself (which they have no way of protecting). The fact that openssl accepts any passphrase is likely a bigger problem in practice than the lack of authentication.

If you want to send something securely, I’m not sure email is the best method. Even if you understand all the risks and pitfalls and side-step the minefields it’s still insecure in non-fixable ways. ProtonMail make a service out if it mitigating those issues as best they can (but even they explain their threat-model and what they DON’T mitigate. Others such as Silent Circle ended up giving up.

You could recommend to those non-technical people to either:

- Use Signal

- Sign up to two free ProtonMail accounts and use those to exchange with one another. That way they’re both e2e and don’t leave the eco-system. And no setting up of PGP keys and such like, and a nice web UI.

If they’re non-technical I wouldn’t suggest PGP IMHO. It’s actually easier to setup S/MIME for non-technical people (I’ve had some success there myself).

Of course part of this is that no one has solved the UX and usability and that it never reached mainstream in most ‘typical’ email clients. To set it all up you have to be fairly technical. When it should just work out of the box - like Signal.

Signal is not secure if you're concerned about the App Store maintainer or Signal themselves having access to your data (you can't know what the contents of the app on the app store are and it my exfiltrate keys. This has been done with other similar apps in the past.)

// This has been done with other similar apps in the past.

Such as?

7zip encrypted archives, the "create protected archive" should be accessible with right click on most platforms (I use the CLI version and I only have a vague memory about the UI)

The problem with this is it's only as secure as the password, and most people choose weak passwords.

Edit: Another is you need to manually enable the checkmark to 'encrypt file names'. Otherwise all file names are in the clear.

(r)age

https://news.ycombinator.com/item?id=21895671

https://github.com/str4d/rage

The thing where you have to deal with raw keys? For non-technical people?

* https://articles.59.ca/doku.php?id=pgpfan:agevspgp

TLDR at the bottom.

It seems the answer is Brian Warner's magic-wormhole. You're gonna see lots of file transfer sites with wormhole in their name, but if you want security you should use the original one, which is BW's m-w.

It is implemented in Python [1], so it's hard to install.

So someone made a Go version of it [2] that has binaries for windows, Mac, Linux, BSD etc. But it's command line so maybe not suitable for lay people.

So another person made a GUI for it that also has binaries for all OS [3].

Also there is an android app [4]. Someone needs to implement an iOS one.

[1] https://github.com/magic-wormhole/magic-wormhole/

[2] https://github.com/psanford/wormhole-william/

[3] https://github.com/Jacalz/wormhole-gui/

[4] https://github.com/psanford/wormhole-william-mobile/

TLDR: ask them to install [5] and [6].

[5] https://github.com/Jacalz/wormhole-gui/releases/

(click on 'Assets' under 'Latest release' and download the zip or tar.gz for your OS)

[6] https://play.google.com/store/apps/details?id=io.sanford.wor...

Try it, it's usage is cute and really feels like magic.

. .

Edit: Discussion from few days ago. The creator is in the comments.

https://news.ycombinator.com/item?id=27262193

Signal (on desktop or smartphone) or https://webwormhole.io/

For webwormhole.io, it's server is a weak spot:

https://news.ycombinator.com/item?id=23024833

Good point.

Signal

You can use gpg with emails without having to deal with keys and stuff: use deltachat (https://delta.chat/en/)

I really don't get this attitude, though I think it must be valid, since I seem to be almost alone in disagreement. I use plain old GPG for a lot of purposes, and I don't find its command-line usage difficult at all. Key management, encryption, decryption, signing — all of these operations are pretty straightforward.

What specific tasks have you found difficult?

It's very hard to simply encrypt a file to a given pubkey (due to the key trust model) compared to, for example, something like age (where it's just `age -r $PUBKEY`). You also have to set GNUPGHOME somewhere and import the key first, you can't easily do it statelessly without tracking mud into the filesystem first.

gpg has had a --recipient-file option for a while now... no need to import it.

I agree that age is a huge improvement over PGP, and the rightful heir to its throne.

However most people complaining about PGP's UI go on to explain that this is why you should use Telegram or WhatsApp. That line of reasoning is just bogus.

Huge improvement? It doesn't even come close. It's yet another half-assed reimplementation of the easiest PGP features to reimplement. There is no web of trust, no smartcard support, not even signing.

Which is why age has gone nowhere, and pretty much everyone keeps using PGP.