Since I seldom need the functionality provided by oathgen (a complete HOTP/TOTP implementation), I typically use goathgen. Goathgen is a simple TOTP library and command line executable written in Go. If all you need is Google Authenticator type one-time codes and like simple CLI programs, you may try it.

Executable usage examples

$ gpg -d encrypted-secret.txt | goathgen
$ cat plaintext-secret.txt | goathgen

Installation via Go

$ go get github.com/62726164/goathgen

To build and install the executable

$ cd main && go build -o goathgen
$ sudo mv goathgen /usr/local/bin

To use the library in your go program

Read main.go to see a simple example

To run unit tests against the library

$ go test -v
    or
$ go test

Notes

1. To use the goathgen executable with a PGP encrypted TOTP secret
   • Obtain a hex or base32 encoded TOTP secret from your service provider.
   • Encrypt the TOTP secret with your PGP key and save the encrypted secret in a file.
   • Securely delete and overwrite the plain-text TOTP secret.
   • Decrypt the TOTP secret and pipe the output to goathgen.
2. goathgen only works in TOTP mode using these TOTP defaults
   • HMAC-SHA1
   • Six digit codes
   • 30 second time step
3. If you need other OATH functionality, edit the goathgen source code.
   • Read the C++ oathgen source code for full OATH functionality
   • https://github.com/62726164/oathgen
4. Run NTP when using goathgen.

• oath
• totp
• hotp
• software