jm + cryptanalysis   3

Meet the Irish master codebreaker you never heard of
In 1943, one of Nazi Germany’s most notorious communication codes was broken by a mild-mannered librarian and family man from Abbeyfeale in west Limerick, Richard Hayes. His day job was director of the National Library of Ireland, but during the Emergency, he secretly led a covert team of cryptanalysts, working feverishly on the infamous “Görtz Cipher” – a fiendish Nazi code that had stumped many of the greatest code-breaking minds at Bletchley Park, the centre of British wartime cryptography.

Astonishingly, the feat was accomplished not in one of the huts at Bletchley Park, but in a now derelict building colloquially known as “The Red House” on Montpellier Hill in Dublin. If this wasn’t an amazing enough feat, Hayes also broke a complex microdot enciphering system which had baffled the American OSS, as well an enciphering system used by the dreaded Sicherheitsdienst (or SD), the intelligence section of the SS. The breaking of the latter code was instrumental in the Allied victory at the Battle of the Bulge.

Few individuals can be said to have altered the course of the second World War on their own, but Hayes was one such individual – and he did it not with a gun, but with a detailed knowledge of the complex algorithms and mathematical permutations involved in the art of cryptography.

(via Colm)
via:colmmacc  crypto  codes  hermann-gortz  wwii  dublin  ireland  richard-hayes  cryptanalysis 
11 days ago by jm
Decoding the Enigma with Recurrent Neural Networks
I am blown away by this -- given that Recurrent Neural Networks are Turing-complete, they can actually automate cryptanalysis given sufficient resources, at least to the degree of simulating the internal workings of the Enigma algorithm given plaintext, ciphertext and key:
The model needed to be very large to capture all the Enigma’s transformations. I had success with a single-celled LSTM model with 3000 hidden units. Training involved about a million steps of batched gradient descent: after a few days on a k40 GPU, I was getting 96-97% accuracy!
machine-learning  deep-learning  rnns  enigma  crypto  cryptanalysis  turing  history  gpus  gradient-descent 
july 2017 by jm
How Advanced Is the NSA's Cryptanalysis — And Can We Resist It?
Bruce Schneier's suggestions:
Assuming the hypothetical NSA breakthroughs don’t totally break public-cryptography — and that’s a very reasonable assumption — it’s pretty easy to stay a few steps ahead of the NSA by using ever-longer keys. We’re already trying to phase out 1024-bit RSA keys in favor of 2048-bit keys. Perhaps we need to jump even further ahead and consider 3072-bit keys. And maybe we should be even more paranoid about elliptic curves and use key lengths above 500 bits.

One last blue-sky possibility: a quantum computer. Quantum computers are still toys in the academic world, but have the theoretical ability to quickly break common public-key algorithms — regardless of key length — and to effectively halve the key length of any symmetric algorithm. I think it extraordinarily unlikely that the NSA has built a quantum computer capable of performing the magnitude of calculation necessary to do this, but it’s possible. The defense is easy, if annoying: stick with symmetric cryptography based on shared secrets, and use 256-bit keys.
bruce-schneier  cryptography  wired  nsa  surveillance  snooping  gchq  cryptanalysis  crypto  future  key-lengths 
september 2013 by jm

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