30 Years Ago

Exactly 30 years ago, Stasi was dissolved. 13 January 1990. 91,000 full time employees and 189,000 unofficial collaborators and informants lost their jobs and privileges. The German government has done a lot to preserve anything which Stasi has ever done. Some links: At this moment in Brussels, inside the EU Parliament there is an exposition on this …

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A New Documentary about WW2 Cryptanalysis of Enigma

A new documentary tells the story of the discovery of one of the most important cryptography papers of all times. We are talking about an extensive technical report written in German language and entitled “Kurzgefasste Darstellung der Auflösungsmethoden”. For some 80 years it has remained classified, part of the so called Gustave Bertrand WW2 archives. It was …

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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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Happy Birthday Bitcoin, 10 Years!

On January 3rd we celebrate 10 years since bitcoin network started operation. Long live all crypto currencies, especially those which actually are real innovators, and bring new technology such as advanced crypto techniques to the market. Let a thousand crypto flowers bloom. P.S. It is also 20 years and 2 days after the introduction of …

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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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The Low Cost of 51% Attacks

A web page shows that many crypto currencies lack protection against 51% attacks. For example to double spend in Dash, one needs to pay only 14K$ per hour. To double spend in bitcoin private, 1000$ will suffice. And course benefits of double spending can easily outweigh the costs. In addition some of the higher numbers are questionable. There …

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Bitcoin Crazy Ride Hits Wall Street

It is a big success for bitcoin and coincides with an incredible price rally where bitcoin has accomplished in 2017. In first days of 2017, bitcoin was worth 1000$. 5 months later in May it was at 2000$, 3 months later in August it was at 4000$, and after another 3 months in November it was at …

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