
Flaw in the Enigma Code - Numberphile
About this video
Numberphile's Dr James Grime explains the flaw in the Enigma machine, namely that a letter could never be encrypted to itself, and how that helped the Allies break the code. It touches on the Bombe and Alan Turing.
Why it appears in the archive
HN points to it as a short, clear explanation of why Enigma was breakable and how search-space elimination works.
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From the Hacker News discussion
Some people might like this from Numberphile which describes the flaw in the enigma machine that British code breakers used to eventually break the code. [VIDEO]
Read original comment ↗In this case, a more relevant example from World War II might be the exploitation of flaws in the Enigma machine, namely: 1) the re-use of common phrases in weather reports, and 2) the fact that a letter could not be encoded as itself in the ciphertext, providing a mechanism of contradiction that drastically sped up elimination of possible settings [LINK] Numberphile gives a nice, succinct explanation [VIDEO]
Read original comment ↗none of it is "brute force", GNFS is a process that rapidly excludes numbers from the search space that cannot be the answer, in principle similar to the way they broke enigma. numberphile has a great video on that one [VIDEO] Also, taking the OP as a "worse case", afaik: 512bit = $8 so 1024 = 8^2 = $64 2048 = 8^2^2 = $4,096 4096 = 8^2^2 = $16,777,216 noting $8 for 512 seems very expensive to me.
Read original comment ↗There's the entertaining bit in the film The Imitation Game (the breaking of Enigma code by Alan Turing) where they realised that a weakness was the daily weather report always containing the words "weatherreport" and "heil bloody hitler" (with obvious addition!) [LINK] or longer version: [LINK] Also a more proper explanation: [VIDEO]
Read original comment ↗