Introduction to basic cryptography

From What The Wiki?!

Most people perceive cryptography to be an arcane science reserved for a handful of scaringly intelligent people. Brenno de Winter, an IT journalist, crypto enthusiast and open source programmer, presented a basic introduction into hand cyphers, which are cryptographic algorithms that can be en- and decoded without a computer or other device, and proved to the audience that cryptography is not only easy, but also can be a lot of fun. Starting with ROT13, the oldest known and probably first cypher, he moved on to mono- and polyalphabetic substitutions to newer, better and still usable forms of encryption. During the course of the presentation, he offered insight on how and why cryptography came up, and how to crack simple cryptos without resulting to pure brute force.

Brenno also offered arguments for a pro-cryptography stance. Cryptography is one of the most important tools in the defense of free speech, and therefore essential for the survival of modern democracy. He also debunked the argument that "You don't need cryptography if you have nothing to hide" by pointing out that, while you might not have to hide anything today, changes in freedom of expression laws could change that anytime. Every reduction of those rights, no matter why, endangers the whole system, and opens doors for more and stricter restrictions. Only through constant work and political pressure can a loss of democracy be prevented. There are numerous cases in human history where adequate encryption has saved lives, and many cases were a lack of it cost untold lives. The Yugoslavian war and world war 2 are just two of the more prominent examples.

After his speech, I had the opportunity to interview Brenno on some questions about freedom of speech and modern cryptography.

Q: What do you think of the concept that, with freedom of expression comes the responsibility to stand by one's word, and therefore anonymity and free speech are incompatible?

A: It's not true. People have a right to say whatever they think, and there shouldn't be a social status or whatever attached to it. If somebody wants to say that he is happy about a terrorist attack, he should have the right to, even if there are good reasons to disagree with him. Because if you are not allowed to tell what you can tell or think, who will determine what I can say? And where's the difference to a totalitarian regime then?

Q: Public key cryptography like PGP is rather popular today. Does pubkey crypto have weaknesses that you think need to be adressed, or is it the end of encryption technology?

A: It's definitely not the end of encryption, but it's a great advancement for users to protect themselves from abuse. What is lacking is not so much technical, but more social. People should be educated in the use of it, and encouraged to actually use it. Another problem is that it's still hard to find trusted third parties for signing, but there is much progress in this field currently.

Q: Is there a price too high to pay for freedom of expression?

A: No, there is no price too high for free speech, but freedom of expression is limited by borders. You are clearly crossing the border as soon as you are undermining other civil liberties or human rights. So for instance, if you call out to kill all jews or muslims, you do not exercise your right of free speech, but you try to spur people on to commit an illegal act. As soon as you exchange one civil right for another one, the whole structure of our legal and democratic system collapses. Our society is based on human rights. In the moment you make that exchange, exchange it for security against terrorism, for example, the terrorists have reached their goal of throwing over our society. This is happening right now, and it scares the hell out of me.

You can see a raw video from the lecture here. If you always harbored an interest for cryptography, but just never had the time or sources to dive into it, I'd really recommend taking a look at this. Brenno also gives out a monthly newsletter on the issue - you can subscribe to it here. The presentation can be seen here.