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https://github.com/rsc/2fa

Two-factor authentication on the command line
https://github.com/rsc/2fa

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Two-factor authentication on the command line

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README 

        
2fa is a two-factor authentication agent.



Usage:



    go get -u rsc.io/2fa



    2fa -add [-7] [-8] [-hotp] name

    2fa -list

    2fa name



`2fa -add name` adds a new key to the 2fa keychain with the given name. It

prints a prompt to standard error and reads a two-factor key from standard

input. Two-factor keys are short case-insensitive strings of letters A-Z and

digits 2-7.



By default the new key generates time-based (TOTP) authentication codes; the

`-hotp` flag makes the new key generate counter-based (HOTP) codes instead.



By default the new key generates 6-digit codes; the `-7` and `-8` flags select

7- and 8-digit codes instead.



`2fa -list` lists the names of all the keys in the keychain.



`2fa name` prints a two-factor authentication code from the key with the

given name. If `-clip` is specified, `2fa` also copies to the code to the system

clipboard.



With no arguments, `2fa` prints two-factor authentication codes from all

known time-based keys.



The default time-based authentication codes are derived from a hash of the

key and the current time, so it is important that the system clock have at

least one-minute accuracy.



The keychain is stored unencrypted in the text file `$HOME/.2fa`.



## Example



During GitHub 2FA setup, at the “Scan this barcode with your app” step,

click the “enter this text code instead” link. A window pops up showing

“your two-factor secret,” a short string of letters and digits.



Add it to 2fa under the name github, typing the secret at the prompt:



    $ 2fa -add github

    2fa key for github: nzxxiidbebvwk6jb

    $



Then whenever GitHub prompts for a 2FA code, run 2fa to obtain one:



    $ 2fa github

    268346

    $



Or to type less:



    $ 2fa

    268346	github

    $