Crypt::HCE_MD5 - Perl extension implementing one way hash chaining encryption
$hce_md5 = Crypt::HCE_MD5->new("SharedSecret", "Random01,39j309ad");
$hce_md5 = Crypt::HCE_MD5->new('KEYBUG', "TheSecret", "junk o rama");
$crypted = $hce_md5->hce_block_encrypt("Encrypt this information");
$info = $hce_md5->hce_block_decrypt($crypted);
$mime_crypted = $hce_md5->hce_block_encode_mime("Encrypt and Base64 this information");
$info = $hce_md5->hce_block_decode_mime($mime_crypted);
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
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 also be found in the examples directory.
The 'KEYBUG' flag is for decrypting data encrypted with an older version of
Crypt::HCE_MD5. There was a bug in the chaining portion that prevented the
full 16 bytes of the previous block from being using in creating the chaining
hash. Decrypt your old data and re-encrypt it without the KEYBUG flag.
The release after this one will have the KEYBUG feature removed, but I'll leave
this version on CPAN
Thanks to Jake Angerman for pointing out the weakness.
Eric Estabrooks, firstname.lastname@example.org