A Linear Annihilator Property and Strong Biases with Original DES S-boxes

In 2004 I have published a paper [Crypto 2004, Santa Barbara] in which I explain the concept of the so called Bi-Linear attack on DES. The old attack was not extremely strong. It is possible to see that two conditions would be necessary for such an attack to somewhat work well in cryptanalysis of DES: There …

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A New Attack on Data Encryption Standard (DES)

There is abundant literature on the security of Data Encryption Standard (DES or 3DES). Today we have released a new way to attack this cipher, see Section 11 in here. Anyone who reads this paper should immediately see that the high confidence which have developed over decades in research community about our ability to design secure block …

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How to Backdoor a Block Cipher

I have written an elementary tutorial and a first proof of concept about how to backdoor a block cipher in a quite general setting. Potentially it applies to any block cipher. Success is not guaranteed though, see the paper. ADDED 2 JAN 2019: a new paper shows that invariants of higher degree are substantially more powerful. …

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XYZ and Saving an Extremely Rare Enigma Machine

Public donations are sought by Pilsudski Institute in London. The most prominent host of the institute is an extremely rare WW2 Enigma machine. This machine was made in France during WW2 to assist Polish code breakers in their daily code-breaking tasks [done in close collaboration with Bletchley Park, UK]. Only two such machines exist, see here …

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UCL InfoSec Visit at Bletchley Park – Friday 29 Sept 2017

Our trip took place 29 Sept 2017.  Some 32 UCL students participated. Students have explored the past in order to find role models for the future.           Due to large numbers, we have split into two groups for a guided Bletchley Park tour, and also had assisted at two bombe demonstrations. …

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How Many 1024-bit Primes Have Backdoors?

So how did the NSA backdoored the Internet or did they??? New ground-breaking paper shows that DSA and DH mod P keys with 1024 bits are vulnerable to practical backdoors which can be exploited to break our secure communications. Few highlights: For such trapdoored primes the DL problem can be solved in 2 months by an academic cluster. The …

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UCL InfoSec Visit at Bletchley Park – 2 Oct 2016

    Home Work After a bombe demonstration by a WW2 veteran Ruth Bourne and BP bombe experts, students have been asked to further study at home how Enigma was broken, see our hand-out. More details can be found in our teaching materials “Enigma and Block Ciphers – 100 years of cryptanalysis with non-commutative combinations …

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Researchers in Cryptography vs. Big Brother

For decades the dominant paradigm in crypto and security research would be: to claim that security vulnerabilities occur accidentally, ignoring major questions such as why there are so many of them and why the “bad scenarios” repeat so many times, concentrate security research on topics of secondary importance, or those which have no importance whatsoever and …

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