crypt(3C)							   crypt(3C)




 NAME
      crypt, setkey, encrypt - generate hashing encryption

 SYNOPSIS
      #include 

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

      void setkey(const char *key);

      void encrypt(char block[64], int edflag);

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

      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 perturb the hashing
      algorithm in one of 4096 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 two characters are
      the salt itself.

    setkey() and encrypt():
      The version of the encrypt() function currently shipped on standard
      HP-UX systems fails when edflag is non-zero (for decryption) and errno
      is set to ENOSYS in order to comply with industry standards and U.S.
      government regulations.  However, fully functional versions are
      available from HP in certain geographic areas, and behave as described
      below:

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

      The block argument to 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 that was set by setkey().  If edflag is zero,
      the argument is encrypted; if non-zero it is decrypted.

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

 WARNINGS
      The return value points to static data whose content is overwritten by
      each call.

 STANDARDS CONFORMANCE
      crypt(): SVID2, XPG2, XPG3, XPG4

      encrypt(): SVID2, XPG2, XPG3, XPG4

      setkey(): SVID2, XPG2, XPG3, XPG4

 Hewlett-Packard Company	    - 2 -     HP-UX Release 9.0: August 1992

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