TOTP generator

This is my minimal-bullshit attempt to make life easier by generating Google Authentication one time passwords locally without need for smartphone.

Building

Prerequisites:

• C99 compatible compiler
• glibc-2.19+ (on older glibc try adding -D_BSD_SOURCE to compiler flags)
• GNU make
• pkg-config
• libcrypto

After installing prerequisites just type

make

to build totp binary.

Extracting secret from QR-code

Save screenshot of browser page with QR code before importing it into Google Authenticator and

zbarimg --raw screenshot.png

zbarimg can be installed

• apt-get zbar-tools for Ubuntu
• emerge media-gfx/zbar for Gentoo
• build manually from https://github.com/mchehab/zbar

Preparing secrets file

Program expects ~/.totp.csv file with secrets and their names separated by a single tab character (not spaces!).

# cat ~/.totp.csv
gmail   otpauth://totp/...
slack   otpauth://totp/...
vpn	otpauth://totp/...

Using totp

After everything is prepared ./totp SECRET_NAME will print 6-digit OTP code.

For example config from section above

./totp vpn

will print one time password for vpn secret.