NAME

       Crypt::HCE_SHA - Perl extension implementing one way hash chaining encryption using SHA

SYNOPSIS

         use Crypt::HCE_SHA;

         $hce_sha = Crypt::HCE_SHA->new("SharedSecret", "Random01,39j309ad");

         $crypted = $hce_sha->hce_block_encrypt("Encrypt this information");
         $info = $hce_sha->hce_block_decrypt($crypted);

         $mime_crypted = $hce_sha->hce_block_encode_mime("Encrypt and Base64 this information");
         $info = $hce_sha->hce_block_decode_mime($mime_crypted);

         $hce_sha = Crypt::HCE_SHA->new("key", "random", 256);  # use SHA256 instead of SHA1

DESCRIPTION

       This module implements a chaining block cipher using a one way hash.  This method of
       encryption is the same that is used by radius (RFC2138) and is also described in Applied
       Cryptography.

       Two interfaces are provided in the module.  The first is straight block
       encryption/decryption the second does base64 mime encoding/decoding of the
       encrypted/decrypted blocks.

       The idea is the the two sides have a shared secret that supplies one of the keys and a
       randomly generated block of bytes provides the second key.  The random key is passed in
       cleartext between the two sides.

       An example client and server are packaged as modules with this module.  They are used in
       the tests. They can be found in the examples directory.

       Thanks to Jake Angerman for the bug report on the bug in key generation for the chaining
       portion of the algorithm

AUTHOR

       Eric Estabrooks, eric@urbanrage.com

SEE ALSO

       perl(1).