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U.S. Army Guide to Code Breaking
sebFlyte writes "From the introduction of this document, the U.S. Army's field manual guide to Cryptanalysis: 'This manual presents the basic principles and techniques of cryptanalysts and their relation to cryptography. Cryptanalytics is the art and science of solving unknown codes and ciphers.'"
You should take a look at tracking down The Codebreakers which is a fasinating read.
"I use a Mac because I'm just better than you are."
This field manual (no. 34.40.2) seems to have a Distribution Restriction placed on it as of March 5, 1990. The index page of the manual features a prominent warning about its restricted nature and a banner at the bottom of the page reads, "For Official Use Only".
Is this document classified or are these just standard warnings with no teeth? Is our dissemination of this 15-yr-old document criminal?
(P.S. - note that the link they used for "here" doesn't even work.
Let's go Hurricanes!!! 2006 Stanley Cup Champions!!!
A good read along with this would probably be Between Silk And Cyanide: A Codemakers War, which gets into, among other things, creation of more secure codes during WW II. An excellent read (I currenly have The White Rabbit on order (story of Yeo-Thomas' activities in France, capture, interrogation and imprisonment))
A feeling of having made the same mistake before: Deja Foobar
I can also highly recommend Between Silk And Cyanide (no referral tags in that link.) Marks is a brilliant writer, and it reads far more like an entertaining work of fiction than a historical narrative.
John
On the other hand, the people we are likely to fight in the near future are probably using fairly low tech methods.
Back when I was doing SigInt for a living in the late 80s, we used all kinds of stuff like burst transmission, line of sight radio relays, and encryption computers. At the same time, the Russians and Czech units we were listening to were using fairly basic cyphers up to batallion and even brigade level. The one I remember most were fairly simple extensions of Polybios squares that encrypted pairs of letters instead of single letters. The sheets changed daily, or a bit more often, so our days were fairly close to the ones described in Codebreakers. The codes switched early in the morning, so we listened to garbage until we had enough cyphertext to break them, then spend the rest of the day decyphering their conversations, and started over again the next morning.
Unfortunately, it was a lot less glamorous than it sounds. Routine military radio traffic is really really dull and predictable.
The higher level radio traffic was usually a bit better protected.
MOS - Military Occupational Specialty--formal job classification, usually expressed as a number or number/letter combination--e.g., 11B Infantryman.
0) 55 47 55 2e 20 55 4e 41 51 2e
1) UGU. UNAQ.
2) HTH. HAND.
3) Hope That Helps. Have A Nice Day.
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Was, sadly. He died about 2 years ago.
His book is very much worth reading, IMAO.
Paul
Lasciate ogne speranza, voi ch'intrate
I agree. An astute observation came from a member the OPFOR, the "Red Army" used at the Fort Irwin, California National Training Center, in briefing materials. Too many commanders used improvised codes instead relying on the tactical codebook or the CEOI; they were very easy to break.
If it's too hard to use, no one uses a system.
Nyekulturniy... Proudly confusing readers and editors since 1981!
My literary forays into the field have been limited, but perhaps one of my favorite reads to date has been Simon Singh's 'The Code Book' (which has been mentioned before).
It's not terribly detailed by way of 'how to', but the history of cryptography/cryptanalysis it offers is fantastic. It's also pretty well known for the contest in the back of it, wherein Mr. Singh offers a reward for the solution to all 10 of the codes (I believe a Swedish team eventually won the prize, shortly after the deadline had passed).
"How like you to drag your keyboard to a gun fight." - Aaron Bedard (BANE)
I've read several comments here about removing this from the /. site because it's secret, but in reality it's anything but. I teach cryptography in college, and the ciphers explained in the document and the codebreaking techniques are strictly old school. Nobody even uses these anymore. Old-style ciphers like Playfair, Hill, and even Vigniere have been crackable by computer in a ridiculously small time for the past 20 years.
The areas of interest for codebreakers are in advanced symmetric ciphers and public-key crypto. For instance, cracking modified Feistel ciphers like 3DES, AES, and Blowfish. To date, nobody has made any advances of note in cracking Blowfish, but you never hear anyone talking about what a good algorithm it is. DES has been cracked for a while now thanks to the 56-bit key problem, but the algorithm is solid and AES (a.k.a. Rijndahl) is based off of the same basic concept, but with a bigger key.
The other area of note is in public-key crypto, such as exponential ciphers (RSA) and elliptic-curve crypto, which uses discrete logarithms to make cracking the code akin to solving an almost impossible math problem.
So don't worry that we just gave the enemy the technology to crack our codes -- the stuff in this document was old in World War I.