Synopsis:
   $crypt(<string> <salt>)

Technical:
   Given an arbitrary string and a "salt" (a randomizer), this function
   returns the input string in a one-way encrypted form.  This function
   depends on the availability of a local crypt(3) library function.  Only
   the first 8 characters of the input string are significant.  The salt
   is a two-character string, and may be composed of any combination of
   any alphanumeric character, a period (.), or a forward-slash (/).
   Additional characters may be available, depending on the crypt(3) in
   use at your site.

Practical:
   This function is primarily used for encrypting passwords, Unix style.
   It is helpful if the input salt is itself sufficiently random.  Case is
   preserved in both the salt and input string.

Returns:
   encrypted input text, or nothing if error

Example:
   $crypt(foobar ab)              returns "foobar" encrypted with salt "ab"

Other Notes:
   As mentioned above, this function relies completely on the availability
   of a local crypt(3) library function.  This function is not available
   on some systems.  Refer to your system's manual pages for more
   information.