The tcb package contains core components of our tcb suite implementing the alternative password shadowing scheme on Openwall GNU/*/Linux (Owl). It is being made available separately from Owl primarily for use by other distributions.
The package consists of three components: pam_tcb, libnss_tcb, and libtcb.
pam_tcb is a PAM module which supersedes pam_unix. It also implements the tcb password shadowing scheme. The tcb scheme allows many core system utilities (passwd(1) being the primary example) to operate with little privilege. libnss_tcb is the accompanying NSS module. libtcb contains code shared by the PAM and NSS modules and is also used by user management tools on Owl due to our shadow suite patches.