totp.c is a small, simple, standalone command line TOTP (RFC6238) without any external dependencies.
totp.c was written by
David M. Syzdek.
The standalone hmac_sha1 implementation is by
Bob Liu.
# use the default rlimit sandbox
make
# use the seccomp sandbox
RESTRICT_PROCESS=seccomp make clean all
# disable the sandbox
RESTRICT_PROCESS=null make clean all
#### using musl
RESTRICT_PROCESS=rlimit ./musl-make
## linux seccomp sandbox: requires kernel headers
# clone the kernel headers somewhere
cd /path/to/dir
git clone https://github.com/sabotage-linux/kernel-headers.git
# then compile
MUSL_INCLUDE=/path/to/dir ./musl-make clean all
Usage: totp <b32_key> [ <interval> [ <offset> ] ]
totp YW2N4W7UBAIAEVCT
# 30 second intervals (default)
totp YW2N4W7UBAIAEVCT 30
# previous window
totp YW2N4W7UBAIAEVCT 30 -30
# next window
totp YW2N4W7UBAIAEVCT 30 30
# read key from stdin
echo YW2N4W7UBAIAEVCT | totp - 30
I needed a simple TOTP application that could be statically linked for use on an old powerpc linux device.