# Learning How Crypto Works

A friend asked me recently to explain some mathematics relating to encryption. The math was a bit beyond the person’s understanding and I looked for a simpler explanation. I found one and I think it will be a big help to many people who want a basic understanding of the math behind how encryption works.

I found the explanations at the Khan Academy: www.khanacademy.com. If you’re not familiar with Khan Academy, you should check it out. The Khan Academy was started in 2006 to provide “a free world-class education for anyone anywhere”. It is a US non-profit. They offer courses on many topics at many levels. School systems around the US and in other countries use it to supplement regular classwork, for example.

The Academy started sort of by accident. In 2004 Khan (a graduate of MIT and Harvard Business School) was tutoring his cousin remotely with simple videos. The videos became popular with friends and relatives so Khan moved them to youtube. They now have a library of over three thousand videos. While many of those videos are very fundamental, others are more advanced. I used to think of them mostly as a tool to help high school students, but they are now far more than that.

When it comes to cybersecurity at Khan Academy there are a few good explanations of complex concepts. One of these is an explanation of cryptographic hash functions. The explanation is clear and does not require more math than is absolutely necessary.

The explanation of public key cryptography including Diffie-Hellman key exchange and RSA encryption requires more mathematics. The Academy explanation is a larger video broken into smaller chunks to help explain the more complex topics. The story and analogy with mixing colors of light is very good and easy to understand – even when they get into complex concepts. If you are interested in seeing how these common cryptographic systems work, this is a good place to begin. Even if you don’t have a strong math background or the desire to learn complex math, this site is for you.

If you are interested in the history of cryptography and how secret messages were sent (and broken) in the past (and some techniques that are still used today), check out their series on Ancient Cryptography.

In May of 2013 Salman Khan received the well-deserved Champion of Learning Award from the American Society for Training and Development (ASTD). According to the ASTD site “The Champion award is presented to an individual outside of the training and development profession whose work and advocacy for learning has impact on the profession.” It is a high honor and I’m glad it went to Khan. I’ve learned a lot from the Academy (and re-learned stuff I had forgotten). Check it out.

In Learning Tree Course 468, System and Network Security we discuss how to use cryptography for confidentiality, integrity and authentication. I look forward to seeing you in one of the classes.

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