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Two-factor authentication with pass and oathtool

published 2020-04-03,updated 2024-02-10

If you're like me, you don't want to depend on your phone to log into a website, and you wish your favorite password manager [1] would support 2FA. Well, it can.

When asked to setup 2FA on a website, get a text code for TOTP. If the website doesn't give you that option, just use zbar [2]. For instance, with the QR code from the GitHub documentation [3]:

$ zbarimg totp-click-enter-code.png
QR-Code:otpauth://totp/GitHub:LyaLya?secret=qmli3dwqm53vl7fy&issuer=GitHub
scanned 1 barcode symbols from 1 images in 0.03 seconds

Once you get the secret, put it in `2fa/github` in `pass`.

Finally, add this to your `.bashrc` (or the equivalent for whatever shell you use):

2fa () { oathtool --totp --base32 $(pass 2fa/"$1" | head -n 1) ; }

You can now get your 2FA codes like this:

$ 2fa github
795864

Finally, you can get Bash completion with this simple script, that you must put in `/usr/share/bash-completion/completions/2fa`:

#/usr/bin/env bash

>/dev/null pushd "${PASSWORD_STORE_DIR:-$HOME/.password-store}/2fa"
    l="$(find . -type f | sed s#^./## | sed s#.gpg\$##)"
>/dev/null popd

complete -W "$l" 2fa

All the tools used in that article are available [4] as [5] packages [6] in the Arch Linux repositories.

1: https://www.passwordstore.org

2: http://zbar.sourceforge.net

3: https://help.github.com/en/github/authenticating-to-github/configuring-two-factor-authentication

4: https://archlinux.org/packages/extra/any/pass/

5: https://archlinux.org/packages/extra/x86_64/oath-toolkit/

6: https://www.archlinux.org/packages/extra/x86_64/zbar/

Complements

It was a post on Lobsters [7] that prompted me to post this. Someone from the comments [8] and a former colleague on Twitter [9] told me about a pass extension [10] I didn't know about which does almost the same thing.

Also, some people think that putting 2FA codes in a password manager defeats the purpose. But in practice TOTP 2FA does not really add much more to the security of my accounts than the strong random passwords I generate with pass. The "second factor" part isn't really the true benefit.

One actual advantage is that nobody on the network can sniff all of my credentials (like digest-based password verification methods). Another, and I think this is the main one, is that the owner of the website has chosen part of the credentials and hence ensured some degree of strength. What I do preserves both of those properties, so I'm fine with it. By the way, note that password managers like 1Password [11] and Passbolt [12] do the same thing.

One thing you can do to improve the security of the whole thing is use 2FA to access pass by storing the GPG key in a Yubikey.

7: https://lobste.rs/s/abmkdz/2fa_2_factor_authentication_terminal_app

8: https://lobste.rs/s/abmkdz/2fa_2_factor_authentication_terminal_app#c_c0y9io

9: https://twitter.com/gawenr/status/1245973593453932544

10: https://github.com/tadfisher/pass-otp

11: https://support.1password.com/one-time-passwords/

12: https://help.passbolt.com/configure/totp/time-based-one-time-password-mobile