rdv live from Tokyo

You're probably familiar with the basic idea of the birthday paradox : If you have $n$ people in a room, what's the probability of t...

(Edited on 20/2/29 and 20/5/19, as noted in line.) The field of quantum computing, broadly constituted, is changing rapidly. Hundreds, ...

Claude Shannon, in his seminal article on the mathematics of cryptography , defined two concepts he called diffusion  and confusion .  In di...

2.1.1 Entropy The single most important concept in cryptography -- indeed, in all of information theory, and inarguably one of the most im...

The general idea of trying to decode messages that are encrypted is known as cryptanalysis . Some of the planet's smartest people have...

Coming soon to a blog near you!

One obvious problem with the most straightforward application of a block cipher is that it's deterministic.  If you just apply the trans...

AES, the Advanced Encryption Standard, has replaced DES.  It is a type of block cipher known as a substitution-permutation cipher .  AES use...

[Important update, 10/25 0630. Dave Bacon has corrected me.  The chip is  fully programmable. I had thought that the choice of coupler patte...

DES, the Data Encryption Standard, was designed by IBM in the 1970s, consulting with the NSA.  DES is a type of cipher known as an iterative...

D-H and RSA are pretty easy to understand, and known to be vulnerable to quantum computers, hence attract a lot of attention. The workhorse ...

See the previous section here . The other algorithm we talk about a lot as being both important and vulnerable to Shor's factoring alg...

Previous post in this series is here . Okay, time to dive into this in more technical depth. Let's go phase by phase: 1.1 Authentica...

See the previous posting if you haven't. An encrypted conversation involves, at the macro level, three phases: Authentication: pro...

I just posted  this introduction  to the project here.  I hope you'll follow along as I fill in the postings. There are two fundament...

At a conference in Berlin in June , I was asked, paraphrasing, about why we change the cryptographic keys used during long communication ses...

My interest in running a blog was tailing off when I lost access to this account, so I let it go for a long time. Now, I have some things to...

I've been thinking about restarting this blog, which has been kind of dormant for a while.  One of the topics I've been thinking abo...

I heard yesterday that Mr. Phillips died on March 13, at the age of 84.  When I heard the news, I cried steadily for half an hour, and am cr...

You friends posting fabulous pictures of Space Shuttle Endeavour's last flyby over California are making me weep.  First, I'm crying...