NAME

       Crypt::UnixCrypt - perl-only implementation of the "crypt" function.

SYNOPSIS

         use Crypt::UnixCrypt;
         $hashed = crypt($plaintext,$salt);

         # always use this module's crypt
         BEGIN { $Crypt::UnixCrpyt::OVERRIDE_BUILTIN = 1 }
         use Crypt::UnixCrypt;

DESCRIPTION

       This module is for all those poor souls whose perl port answers to the use of "crypt()"
       with the message `The crypt() function is unimplemented due to excessive paranoia.'.

       This module won't overload a built-in "crypt()" unless forced by a true value of the
       variable $Crypt::UnixCrypt::OVERRIDE_BUILTIN.

       If you use this module, you probably neither have a built-in "crypt()" function nor a
       crypt(3) manpage; so I'll supply the appropriate portions of its description (from my
       Linux system) here:

       crypt is the password encryption function. It is based on the Data Encryption Standard
       algorithm with variations intended (among other things) to discourage use of hardware
       implementations of a key search.

       $plaintext 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 algorithm in one of 4096 different ways.

       By taking the lowest 7 bit of each character of $plaintext (filling it up to 8 characters
       with zeros, if needed), a 56-bit key is obtained. This 56-bit key is used to encrypt
       repeatedly a constant string (usually a string consisting of all zeros). The returned
       value points to the encrypted password, a series of 13 printable ASCII characters (the
       first two characters represent the salt itself).

       Warning: The key space consists of 2**56 equal 7.2e16 possible values.  Exhaustive
       searches of this key space are possible using massively parallel computers. Software, such
       as crack(1), is available which will search the portion of this key space that is
       generally used by humans for passwords. Hence, password selection should, at minimum,
       avoid common words and names. The use of a passwd(1) program that checks for crackable
       passwords during the selection process is recommended.

       The DES algorithm itself has a few quirks which make the use of the crypt(3) interface a
       very poor choice for anything other than password authentication. If you are planning on
       using the crypt(3) interface for a cryptography project, don't do it: get a good book on
       encryption and one of the widely available DES libraries.

COPYRIGHT

       This module is free software; you may redistribute it and/or modify it under the same
       terms as Perl itself.

AUTHORS

       Written by Martin Vorlaender, martin@radiogaga.harz.de, 11-DEC-1997.  Based upon Java
       source code written by jdumas@zgs.com, which in turn is based upon C source code written
       by Eric Young, eay@psych.uq.oz.au.

CAVEATS

       In extreme situations, this function doesn't behave like crypt(3), e.g. when called with a
       salt not in [A-Za-z0-9./]{2}.

SEE ALSO

       perl(1), perlfunc(1), crypt(3).