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 in-
          tended 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 decrypt-
          ed.

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

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













     April, 1990                                                     1