crypt(3G)                                                  crypt(3G)


       NAME
             crypt, setkey, encrypt - generate encryption

       SYNOPSIS
             cc [flag . . . ] file . . . -lgen [library] . . .
             #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 encryption algorithm with variations intended (among
             other things) to frustrate use of hardware implementations of
             a key search.

             key is the input string to encrypt, for instance, a user's
             typed password.  Only the first eight characters are used; the
             rest are ignored.  salt is a two-character string chosen from
             the set a-zA-Z0-9./; this string is used to perturb the
             hashing algorithm in one of 4096 different ways, after which
             the input string is used as the key to encrypt repeatedly a
             constant string.  The returned value points to the encrypted
             input string.  The first two characters of the return value
             are the salt itself.

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

             The block argument of encrypt is a character array of length
             64 containing only the characters with numerical value 0 and
             1.  The argument array is modified in place to a similar array
             representing the bits of the argument after having been
             subjected to the hashing algorithm using the key set by
             setkey.  The argument edflag, indicating decryption rather
             than encryption, is ignored; use encrypt in libcrypt [see
             crypt(3X)] for decryption.





                           Copyright 1994 Novell, Inc.               Page 1

      crypt(3G)                                                  crypt(3G)


         Errors
            If edflag is set to anything other than zero, errno will be
            set to ENOSYS.

      REFERENCES
            crypt(3X), getpass(3C), login(1), passwd(1), passwd(4)

      NOTICES
            The return value for crypt points to static data that are
            overwritten by each call.






































                          Copyright 1994 Novell, Inc.               Page 2