brainwagon

Okay, this is a minor hack, but I thought it was fun, so I thought I’d write it up here. My original code for simulating the Chaocipher machine proceeded as follows: it found the character in the plaintext wheel (by linear search), then rotated each wheel to get the plain and cipher text entry to […]

Well, I didn’t have much time left to work on Chaocipher last night, so I left it running on Exhibit 1. It claimed to recover a key that allowed it to match 601 characters of input, but found no better match. But it also uncovered an error in my code. It doesn’t appear that the […]

My brain has got a bug now. It’s called Chaocipher. Despite the fact that I’m spending my days off with my family, I find that in my odd moments my brain keeps leaping back to Byrne’s cipher. The other night I implemented the basics of key recovery using a chosen plaintext attack (if you have […]

So, first thing this morning, before I had even had coffee or blinked the sleep from my eyes, I decided to try a chosen plaintext attack against Chaocipher. I created a file consisting entirely of 2000 A’s, and passed it through Chaocipher. Here is my output: PKLSD MAVZC UXHEP KLSDM AVZCU XHEPK LSDMA VZCUX HEPKL […]

Okay, insomnia got me, so I went ahead and implemented it in Python. It appears to work reasonably well, at least it successfully deciphers their test message. You can specify the key by specifying the -c and -p options, which are the settings for the cipher and plain wheels. You should pass a permutation of […]

Stumbling back through articles in Slashdot, I found a pretty nifty article on one of my favorite subjects: historical cryptography. The story goes that back in 1918, a cipher system/machine was invented by John F. Byrne. Rumor says that it was very strong, and yet could be implemented using a mechanism that would fit in […]

WARNING: if you are working on this code, this article contains spoilers which may blunt your own intellectual satisfaction in working on it yourself, including some recovered keys. Okay, I’m home, and feeling pretty jet-lagged, so this might be wrong in some way that additional sleep will reveal, but I wanted to get this out […]