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Go presubmit

gauth: replace Google Authenticator

Installation

With a Go environment already set up, it should be as easy as go install github.com/pcarrier/gauth@latest.

Eg, with GOPATH=$HOME/go (its default), it will create a binary $HOME/go/bin/gauth.

Usage

  • In web interfaces, pretend you can't read QR codes, get a secret like hret 3ij7 kaj4 2jzg instead.

  • Store one secret per line in ~/.config/gauth.csv, in the format name:secret. For example:

      AWS:   ABCDEFGHIJKLMNOPQRSTUVWXYZ234567ABCDEFGHIJKLMNOPQRSTUVWXYZ234567
  Airbnb:abcd efgh ijkl mnop
  Google:a2b3c4d5e6f7ghij
  Github:234567qrstuvwxyz
  otpauth://totp/testOrg:testuser?secret=AAAQEAYEAUDAOCAJ======&issuer=testOrg&algorithm=SHA512&digits=8&period=30

  • Restrict access to your user:

      $ chmod 600 ~/.config/gauth.csv

  • Run gauth. The progress bar indicates how far the next change is.

      $ gauth
             prev   curr   next
  AWS        315306 135387 483601
  Airbnb     563728 339206 904549
  Google     453564 477615 356846
  Github     911264 548790 784099
  [=======                      ]

  • Run gauth KEYNAME to print a specific key with progress bar.

  • Run gauth KEYNAME -b to print a bare current key.

      $ gauth Google -b
  477615

  • Run gauth KEYNAME -s to retrieve an accounts secret from the config.

      $ gauth Google -s
  your_secret_for_google

  • gauth is convenient to use in watch.

      $ watch -n1 gauth

  • Remember to keep your system clock synchronized and to lock your computer when brewing your tea!

  • If you find yourself needing to interpret a QR code (e.g. exporting a code from an existing Google Authenticator setup, on a phone to which you do not have root access), then gauthQR may be useful.

Adding and removing keys

  • Run gauth KEYNAME -a to add a new key.

      $ gauth Google -a
  Key for Google: examplekey
  Current OTP for Google: 306726

  • Run gauth KEYNAME -r to remove an existing key.

      $ gauth Google -r
  Are you sure you want to remove Google [y/N]: y
  Google has been removed.

Encryption

gauth supports password-based encryption of gauth.csv. To encrypt, use:

    $ openssl enc -aes-128-cbc -md sha256 -in ~/gauth.csv -out ~/.config/gauth.csv
    enter aes-128-cbc encryption password:
    Verifying - enter aes-128-cbc encryption password:

gauth will then prompt you for that password on every run:

    $ gauth
    Encryption password:
               prev   curr   next
    LastPass   915200 479333 408710

Note that this encryption mechanism is far from ideal from a pure security standpoint. Please read OpenSSL's notes on the subject.

Compatibility

Tested with:

  • Airbnb
  • Apple
  • AWS
  • DreamHost
  • Dropbox
  • Evernote
  • Facebook
  • Gandi
  • Github
  • Google
  • LastPass
  • Linode
  • Microsoft
  • Okta (reported by Bryan Baldwin)
  • WP.com
  • bittrex.com
  • poloniex.com

Please report further results to [email protected].

Rooted Android?

If your Android phone is rooted, it's easy to "back up" your secrets from an adb shell into gauth.

# sqlite3 /data/data/com.google.android.apps.authenticator2/databases/database \
          'select email,secret from accounts'

If your phone isn't rooted, you may have luck with the gauthQR tool mentioned in the Usage section above.

Really, does this make sense?

At least to me, it does. My laptop features encrypted storage, a stronger authentication mechanism, and I take good care of its physical integrity.

My phone also runs arbitrary apps, is constantly connected to the Internet, gets forgotten on tables.

Thanks to the convenience of a command line utility, my usage of 2-factor authentication went from 3 to 10 services over a few days.

Clearly a win for security.