Man Pages – Linux Manual Pages

DES_fcrypt, DES_crypt, DES_enc_read, DES_enc_write – DES encryption
USAGE
#include

void DES_random_key(DES_cblock *ret);

int DES_set_key(const_DES_cblock *key, DES_key_schedule *schedule);
int DES_key_sched(const_DES_cblock *key, DES_key_schedule *schedule);
[...]

crypt – password and data encryption
USAGE
#define _XOPEN_SOURCE
#include <unistd.h>

char *crypt(const char *key, const char *salt);

DESCRIPTION
crypt() is the password encryption function. It is based on the [...]

useradd – Create a new user or update default new user information
USAGE
useradd [-c comment] [-d home_dir]
[-e expire_date] [-f inactive_time]
[...]