crypt(3C)                                               crypt(3C)



NAME
     crypt, encrypt - generate DES encryption

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

     void encrypt(block,edflag)
     char *block;
     int edflag;

DESCRIPTION
     crypt is the password encryption function.  It is based on
     the NBS Data Encryption Standard (DES), with variations
     intended to frustrate the use of DES hardware
     implementations for key search.

     key is a user's typed password.  salt is a 2-character
     string chosen from the set [a-zA-Z0-9./]; this string is
     used to perturb the DES algorithm in one of 4,096 different
     ways, after which the password is used as the key to encrypt
     repeatedly a constant string.  The returned value points to
     the encrypted password.  The first 2 characters are the salt
     itself.

     The encrypt entry provides (rather primitive) access to the
     actual DES algorithm.

     The argument to the encrypt entry is a character array of
     length 64, containing only the characters with numerical
     value 0 and 1.  The argument array is changed in place to a
     similar array representing the bits of the argument after
     having been subjected to the DES algorithm.  If edflag is
     zero, the argument is encrypted; if nonzero, it is
     decrypted.

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

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

     crypt(1), login(1), passwd(1) in A/UX Command Reference











January 1992                                                    1