Tuesday, June 10, 2008

One-time Pad Tool

I just uploaded the new software tool CT-46 OTP to perform one-time pad encryption. The training tool takes a plaintext and one-time pad key, converts the plaintext into digits and calculates the ciphertext. The CT-46 checkerboard is used to convert the text into digits. The program contains instructions on how to use the pencil-and-paper version and the conversion table.

The software is meant for training purposes only, as we all know there's no such thing as a secure computer. The only secure computer is a stand-alone laptop, stored in a 100% burglar proof vault . It's useless to run a perfect crypto system - or any crypto software for that matter - on a normal computer, given the many viruses, trojans, spyware and countless unidentified processes. The software however is ideal to train your encryption skills. The only truly secure way to apply one-time pad encryption still is simply with pencil and paper.

More about one-time pads at my one-time pad page, including an extensive Guide To Secure Communications with One-time Pad (pdf). The freeware CT-46 Tool is available at my download page.


[WinAmp] said...

Well, in some cases even a standalone laptop locked in a safe isn't really *the* safest ;)

David Richardson said...

I'm no cryptographer, but I have been giving some thought to secure encryption.

What about a ROT-n encrytion where n represents the position in the alphabet of the letter of the key. For example if my password is "secret" then the first letter would be replaced with its value +19, the second letter would be its value +5, the third letter +3, etc.

It would seem to me that in this way you would never be able to figure out which rotation is used without knowing the password. And the larger your password, the more secure it would be..

Dirk Rijmenants said...

Hi David,

what you suggest is called a poly-alphabetic cipher. These are totally insecure and easily broken by a frequency count of all 1st, 2nd, 3th... letters seperately. All these types of encryption are variants of the Vigenere cipher, and all are insecure.

A poly-alpha cipher could be totally secure if you would select a random key letters for each individual message letter, but then, that's what we call a one-time pad.