CRYPT(3C)               STANDARD C LIBRARY              CRYPT(3C)


NAME
     crypt, setkey, encrypt -- generate hashing encryption


SYNOPSIS
     #include <unistd.h>

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

     void setkey(const char *key);

     void encrypt(char *block, int edflag);


DESCRIPTION
     crypt is the password-encryption function.  It is based on a
     one-way  hashing  encryption   algorithm   with   variations
     intended  to discourage use of hardware implementations of a
     key search (among other things).

     key is a user's typed password.   salt  is  a  two-character
     string  chosen from the set (a-zA-Z0-9./).  This  string  is
     used to  disturb  the hashing  algorithm   in  one  of  4096
     different  ways, after which the password is used as the key
     to encrypt a constant string repeatedly.  The returned value
     points  to the encrypted password.  The first two characters
     are the salt itself.

     The setkey and encrypt   entries  provide   access  to   the
     actual   hashing  algorithm.   The  argument  of setkey is a
     character array of 64 bits in length  containing   only  the
     characters  with  a numerical of  value  0  and  1.  If this
     string is divided into groups of 8,  the  low-order  bit  in
     each  group  is  ignored; this produces a 56-bit key that is
     set into the machine.  This is the key that is used with the
     hashing  algorithm  to  encrypt  the  string block  with the
     encrypt function.

     The argument to the encrypt entry is a character array of 64
     bits in length containing only the characters with a numeri-
     cal value of 0 and 1.  The argument array  is  modified  (in
     place) to a similar array representing the bits of the argu-
     ment after being subjected to  the  hashing  algorithm.   It
     uses  the  key set by setkey.  ignored is unused by encrypt,
     but it must be present.


SEE ALSO
     login(1), passwd(1), getpass(3C), passwd(4)


NOTES
     The return value points to static data that  is  overwritten
     by each call.



SUPER-UX            Last change: Nov 18, 1996                   1