crypt is a very simple program that emulates the programs in the libsrp found in http://srp.stanford.edu. It is intended for use in places where you don't expect srp authentication to be the performed to system users. If this is the case use libsrp and the pam modules provided. Libsrp uses two files. One called 'tpasswd' which holds usernames and verifiers, and 'tpasswd.conf' which holds generators and primes. How to use crypt: Run: crypt --create_conf /etc/tpasswd.conf * This will create tpasswd.conf which holds the g and n values for SRP protocol (generator and a large prime). Run: crypt --passwd /etc/tpasswd --passwd_conf /etc/tpasswd.conf -u test * This will create /etc/tpasswd and will add user 'test' (you will also be prompted for a password). Verifiers are stored by default in the way libsrp expects (using a modified SHA()). However using this tool you may also specify blowfish crypt instead of SHA (see --crypt parameter). Run: crypt --passwd /etc/tpasswd --passwd_conf /etc/tpasswd.conf --verify -u test * You will be promted for a password, and if this password matches the one in /etc/tpasswd you will get an ok.