Articles Tagged with "Crypto"

19/08/2007: TrivialEncoder/0.2

An update to my PHP encryption class. Despite the name, it’s becoming a pretty sophisticated encyption machine. New encryption algorithms added:

Vigenerè cypher
One-Time Pad
Bruce Schneier’s Superencyption
Various other methods using the MCrypt library

The TrivialEncoderManager class has been obsoleted by TE_Machine, an abstract class with several different child classes for encoding, decoding and analysis. TE_Machine has a greatly improved parser for methods, which has made it a lot easier for me to add additional functionality such as the ability to analyse an encryption technique to see how strong it would be, and to check whether the output would be ASCII-safe. TrivialEncoderManager is still present, but is deprecated and will be removed next release.

01/08/2007: PHP Encryption Class

Here’s a simple PHP library for encoding and decoding text.

Examples:

<?php
$trivialencoder_auto = FALSE;
include 'TrivialEncoder.class.php';

$manager    = new TrivialEncoderManager;
$plaintext  = 'Hello world';
// Chain together Triple DES, Memfrob and Base64 encoding.
// Note: 3DES encoding is passed an (optional) key "mysecretkey".
$encoding  = '3des mysecretkey;memfrob;base64';
$cyphertext = $manager->encode($encoding, $plaintext);
echo $manager->decode($encoding, $cyphertext); // Hello world
?>

24/07/2007: Cryptography Challenge

Here’s a challenge. Decrypt…

aWt6eWZlaWEKfWJjeWFvcwppa3p5ZmVpYQpvaWJlCmZjZ2sKZmNnawp5
emtpbwpub2Z+awpleWlreApkZXxvZ2hveApvaWJlCmhrZG0KeXpraW8Ka
Wt6eWZlaWEKemt6awppa3p5ZmVpYQpmY2drCm9pYmUKa2Z6YmsKeW
NveHhrCm9pYmUKeXpraW8KZmNnawpvaWJlCmtmemJrCnxjaX5leApvaW
JlCnl6a2lvCmtmemJrCnl6a2lvCmlia3hmY28KZXlpa3gKZ2NhbwpnY2FvCm9
pYmUKZGV8b2dob3gKfmtkbWUKeXpraW8KZXlpa3gKZGV8b2dob3gKeX
praW8KfmtkbWUKZXlpa3gKaHhrfGUKc2tkYW9vCmNkbmNtZQpkZXxvZ2h
veAphY2ZlCnljb3h4awp+a2RtZQpvaWJlCnhlZ29lCnl+ZXoKaWJreGZjbwpl
eWlreAp5fmV6Cn9kY2xleGcKYWNmZQp5emtpbwppYmt4ZmNvCmZjZ2sK
a2Z6YmsKY2RuY21lCmdjYW8KY2RuY21lCmRlfG9naG94Cm1lZmwKeXpra
W8KaWJreGZjbwp4ZWdvZQpvaWJlCm5vZn5rCmNkbmNtZQp+a2RtZQp5f
mV6

steg-encode.pl

====

steg-encode.pl is a basic tool for hiding secret messages in images. It comes with a friend: steg-decode.pl.

Download

Usage Example

To hide a message in an image, use the following syntax.

steg-encode.pl image message output

Output should be to either an uncompressed image file or a non-lossy compressed image file, and should be 24-bit colour. Formats such as PNG or Windows Bitmap are ideal.

An example is:

steg-encode.pl test-in.png test-in.txt test-out.png

To convert back:

steg-decode.pl image output

And to…

Cryptography

====

This page contains a few things related to cryptography (obscuring information) and steganography (hiding information), including my introduction to PGP and the steganography challenge.

You might also be interested in steg-encode.pl, my attempt at a basic steganography tool.

An Introduction to PGP

What is That Mumbo Jumbo at the Bottom of Your Email, Toby?

That, my friend, is a PGP signature. It probably looks something like this:

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.6 (GNU/Linux)

iD8DBQE8fU94dS33bVJ0/loRAsznAJ9Xqwgd+n+gAzrmmVZckWPBRenoWACfSp0q
z5Fjj2G+0UoZm6yxOjCWKL0=
=Gc4C
-----END PGP SIGNATURE-----

It is possible that your email client displays it as an attachment. Outlook (and Outlook Express) displays the main body of my messages as an attachment as well. This behaviour is incorrect. (See <a…

A Beginner's Guide to Cyber-Rights

Learn about your rights online and who is trying to take them away from you!