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Encryption Security

British WW II Codebook Online 37

Posted by jamie from the real-dead-trees dept.
An A.C. pointed out Keith Lockstone's website which contains a complete scan of the Second World War codebook "British Cypher No. 5." An interesting look into history. "...when on 10 June [1943] the Admiralty at last replaced Naval Cipher No. 3 with No. 5, which proved quite secure, it was plain that the U-boats could never regain their former authority."
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British WW II Codebook Online More

British WW II Codebook Online

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  • To be exact it was founded as the Personal bodyguard formation for Hitler himself after the SA began to take on entirely too many unruly aspects for HitlerS' taste. Well, at least as far as persoanl security goes. The SS eventually evolved into two branches, the Waffen, or armed SS, thse folks with panzers that everyone at d-day was so worried about and a camp gaurd formation, which was in charge of concentration camp control.
  • A good test of a crypto system is the amount of random data that is used to encrypt/decrypt.

    If everybody downloaded a copy of a crypto system that was the same, and used it without providing random data all copies would scramble exactly the same way.

    The German Enigma cipher only used enough random data to produce about 19600-531400 possible unique keys.

    The theoretical random setting of three or four rotors each having 27 characters of the alphabet provided the random factor. The rest of the enigma machine was hardwired and would substitute characters in a fixed knowable way.

    Minimal contemporary crypto systems use enough random data to produce at least 2^72 unique keys. As technology is bringing the cost of cracking these systems lower and lower these large numbers will soon seem ridiculously small.

    It could be argued that many contemporary crypto systems use pseudorandom data to encrypt. Often times the actual number of likely keys produced is a subset of the theoretical number possible.
  • This was the only US code the Japanese never cracked.

    Not true at all. The Japanese had basically no success cracking any Allied codes except for low-level weather codes. Whereas their codes were mostly an open book.

    The Navajo "code-talkers" were an excellent innovation, though, because (a) the language is obscure and has a very strange structure, with no native speakers available to the Japanese, and (b) they allowed for quick communication with no encryption/decryption time lag.

    A good source on this is a book called Combined Fleet Decoded, about the intel war in the Pacific.

    -Doug

  • What is presented here is more of a code than a cypher. The differentiation consists of how the plaintext is rendered secure. In this instance, one five letter group replaces one or more letters or words. This last is the key difference, since most cyphers replace one letter by one or more letters/numbers/both. It could be argued that the other difference is that most cyphers (these days, at least) are machine-hosted and not worked up on a code-pad as would have been the case with Admiralty No. 5. Have a look at the papers hosted on this site for further amplification and some rather thought-provoking information...not to mention a lovely photo of a bit of Ireland. Cheers, Andrew
  • You can scan something without it being a data monster.

    ...and even Stop/Back are a bit sluggish to respond
  • | There is (sic) somewhere around 50 or 60
    | speakers of Navajo left in the world.

    As others have pointed out, this is simply false. If you live in the western half of the USA or Mexico, simply tune your AM radio to KTNN [navajoland.com], 660 kHz. at night to hear Navajo music, news, sports, and the like. I sincerely doubt a 50,000 watt station would last long with only 60 listeners!

    Earl Higgins

  • I have an american based mirror of the PDF file up, also. You can download it here [html.com]

    Much handier than printing out a couple dozen GIFs :-)

    Best,
    Adam

  • The number tables exhibit a weakness that is best explained by this article [newscientist.com] on the New Scientist Web Site [newscientist.com].

    Benford's Law (see the above article) states that given a random assortment of real-world numbers, 30% will start with a 1, 18% start with a 2 and so forth. Because the table lists the same number of values for each number, it follows that the numbers beginning with '1' will be used a lot more. Although unlikely, this may compromise the security of the code if it is used to encrypt numbers extensively.

    You can check Benford's Law for yourself. Try it with share prices; career earnings of sportspeople, movie stars or racehorses; areas or populations of countries; all real-world numbers on the first 10 pages of any newspaper; and so on.

    Because Benford's Law wasn't discovered until after the cipher was created, it is understandable that the cipher did not allow for this odd property of numbers.
    --

  • ...it still doesn't come close to the US using the language of the Navajo people to send out encoded messages. This was the only US code the Japanese never cracked. And tragically, it may soon be lost to us, too. There is somewhere around 50 or 60 speakers of Navajo left in the world.
    --
    Matt Singerman
  • Oh man, if the Germans invent a time machine, we're all screwed...

  • ..you are on a slow modem !!
    The scanned images (each 200-800K) take fscking ages to upload and jammed my browser (Netscape) for a while.

    Not all of us have DSL or Cable modems
  • ..how secure would ciphers such as this be today and how are they attacked ?
  • Would reprinting this book be considered copyright violation [slashdot.org]?

    Even if the book wasn't copyrighted in the U.S., supposedly the Sonny Bono-named copyright extension was "to bring us in line with European convention" which is life plus 70 years, right?

    Jay (=
    (As the Boston Globe article [boston.com] says, copyright extensions do more than protect "Steamboat Willie"...)
  • It's all right mate, they did invent one, but then we copied it and changed the ciphers.

    jsm
  • I think with a population of over 250,000 in the Navajo nation, more than 50 or 60 would still speak it. Could be wrong, tho'.

    There's more info at the Navy's History site:

    http://www.history.navy.mil/faqs/faq61 -2.htm [navy.mil]

    They've even got the Navajo dictionary. Turns out that the system was more than just the Navajo language and a few code words, since even a captured Navajo couldn't decipher it.
  • Now, who's working on the Perl [perl.org] script, admiral_5.pl ?

    This is doubtless not proof against the serious cryptographers of the NSA, but it would be most entertaining to have a PalmPilot utility for it...

  • What's the problem, here?

    1. The story says that the codebook is scanned. Hello? Know what a scanner is?

    2. There's a nifty button on Netscape and Explorer called Stop. There's another one called Back. I'm sure anyone who finds the download too long can hit either of them and don't need someone writing an alarming title as if the site contained a virus or something.

    I say starve the karma monster.

    "The wages of sin is death but so is the salary of virtue, and at least the evil get to go home early on Fridays."

  • If you read the pages outside of the US, but linked through a US cache, the CIA will arrest you for arms smuggling and force you to use Windows 2.0 until you confess.

    (Windows 95 is banned, under the Geneva Convention.)

    Seriously, can someone add this to the International Patches, just for the fun of it? :) (Ok, well, maybe not so seriously, then! :)

  • Someone's read Fatherland :)
  • This is a fascinating document. But it just emphasises what a fundamental advance public key cryptography was.
  • Definately an interesting document, although unfortunately incomplete. I think this highlights an important part of our history, the granfather of electronic information warfare as we know it today. In WW2 the use and breaking of "unbreakable" codes were key to unit mobility and strategy, or to fending off such an advantage. Although not all Field Marshalls and Generals understood or adopted this as fact... The breaking of ENIGMA was a major part of the WW2 ground war, and the eventual breaking of the German Navy's code (The code name for which escapes me now)being a major part in hunting the U-Boat wolfpacks of the atlantic ocean. Each break when combined with inventions like sonar, radar and new military technology, such as destroyers armed with hedgehogs and depth charges, enabled the allies to avoid the heavy blow from the axis powers that each major strike was intended to be. It also enabled various Allied groups to start campaigns of disinformation before D-day, such as the creation of an entire mythical US Army located in the UK, spoon fed to the Germans, and then confirmed by intercepting german encrypted radio traffic. Today information warfare has many more facets and exploitations in the field, but the general goal never changes, know what the enemy is thinking, and if you cant, tell them what to think. So the real question is, what form will electronic warfare evolve into in say 100 years?
  • Yes, some of us have OC-3 and 100 mbit ethernet links.
  • The Ethnologue [sil.org] (which is the definitive reference on such matters) reports 148,530 speakers including 7,616 monolinguals [sil.org] out of 219,198 ethnic Navaho (1990).
  • Text weighting is useful for quickly finding the key in brute force attacks. You can verify that you have the correct key at the speed of light.

    As a simplistic example if you were to assign an LED to each position in a ciphertext, then try each possible key turning on LEDs only when the character assigned is equal to a space..

    N0typinglik3thiswouldn'thelpth3s3syst3msar3mucht 0s0phiticat3d!
  • Hey, how do you think Turing cracked Enigma?

    All that "Computer Scientist" stuff was just a cover. He was actually an agent sent from the far future to prevent the 1965 nuclear exchange between a downtrodden US and a Nazi controlled Europe.
  • If anyone finds this stuff interesting, go out
    RIGHT NOW and buy "The Code Book" by Singh. It
    details the complete history of Codes and Ciphers
    and includes many great examples of how they
    were used/cracked. Amazing read!

  • I'm going to re-do the page soon. It was rushed out to put on a sci.crypt thread. Keith Lockstone.
  • You can read a very short discussion of the Navajo code talkers on the NSA Museum's page at
    www.nsa.gov/museum/talkers.html [nsa.gov].

    They must not be using their codebreaking machines to run this site, as it seems the /. Effect has struck again. :-)

  • PDF alternative and copyrights (Score:3)

    by jw3 ( 99683 ) on Tuesday November 16, 1999 @06:16AM (#1528844) Homepage
    First - I don't think this is a copyright violation - the book has 235 pages, and only 10% of them are reproduced, which is roughly what you may reproduce from a book or article without permission (as far as I know, of course).

    Second, BEWARE. This page is lame - all gifs on a single page, and they are HUGE. For my own purposes I downloaded them with wget, converted to ps and finally produced one single PDF file. You can download it here [uni-heidelberg.de]. This is my student account, and in Germany, so if someone can put it for all the slashdotters in USA on an american server and notify me I would be grateful.

    Regards,

    January

  • An excellent book and movie - the whole concept is one that has not been explored that much, although the reason for the downlfall is a bit weak.

  • Navajo language is not becoming extinct! (Score:2)

    by Anonymous Coward

    I suspect you have confused the Navajo with some other Native American tribe, as the Navajo are not nearly extinct but are, in fact, the largest tribe in the US.

    The Navajo live in the Four Corners region of the southwest (the intersection of Utah, Arizona, Colorado, and New Mexico) on a large reservation. You can easily find their reservation on a map of Arizona.

    While the Navajo population had been reduced to about eight thousand after the United States' war with them -- run by the infamous Colonel Christopher "Kit" Carson -- concluded in 1864, their numbers greatly recovered upon their return to northern Arizona. They are now the largest Native American tribe, having approximately ninety thousand members according to the 1990 census. And they continue to speak Navajo.

    You can read a very short discussion of the Navajo code talkers on the NSA Museum's page at www.nsa.gov/museum/talkers.html [nsa.gov].

    If you are interested in general information about the Navajo, including their history and rituals, check out: www.ancestral.com/cultur es/north_america/navajo.html [ancestral.com].

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