Re: [Cfrg] Crystalline Cipher

[Tony Arcieri <[e-mail]>]

On Fri, May 22, 2015 at 1:02 PM, Mark McCarron <[e-mail]>
wrote:

> To understand the principles behind Crystalline, I would recommend
> brushing up on Lorenz and Enigma.


Hi Mark,

I'm quite familiar with Lorenz and Enigma, both of which are considered
extremely broken today.

Enigma contained a bias because it never mapped a letter to itself. Any
such bias is sufficient to break a cipher.

Your cipher is full of similar biases:

http://www.freecx.co.uk/cryptanalysis/Crystalline/Crystaline_3D.jpg

If it were a good cipher, it'd appear flatter:

http://www.freecx.co.uk/cryptanalysis/Crystalline/RC4_3D.jpg

Note that RC4 is not a good cipher. You may not know it, but Kenny was part
of a team that found such biases in RC4.

Your cipher has biases. Therefore it's broken. Period. I know you disagree,
but you're wrong. Period. Your cipher is broken. End of story.

By modern standards, your cipher should be indistinguishable from random
data even in the presence of a chosen ciphertext attack, something I'm
fairly certain you're not even familiar with:

https://en.wikipedia.org/wiki/Ciphertext_indistinguishability

Your cipher is obviously distinguishable from random data, simply by
looking at an image of the ciphertext:

https://i.imgur.com/MWmMc0J.png

If you have a genuine interest in cryptography, I hope you take these
things to heart, study them, and improve your knowledge of cryptography.