Gambling with Secrets: an Introduction to Cryptography
Art of the Problem is a team of people making web video series about great problems. Their first series is an introduction to cryptography and cryptanalysis, and it's one of the most approachable I've seen.
If you've ever asked yourself questions like:
- How can two people communicate securely even if somebody is listening in on the conversation?
- How can two people have an encrypted conversation without meeting?
- What does randomness mean? Are things that "look random" secure?
- What is the most secure cryptographic cipher?
- How did the Allied Forces break Nazi Germany's "super-secure" Enigma machine during World War II?
...you'll enjoy this miniseries.
No special background in mathematics is required, and it touches on many subtle mistakes that huge companies are still making today. It consists of 8 parts/chapters, each lasting about 5-10 minutes.
Part 1: Introduction to Cryptography
Part 2: Prime Factorization
Part 3: Probability Theory & Randomness
Part 4: Private Key Cryptography
Part 5: Encryption Machines
Part 6: Perfect Secrecy & Pseudorandomness
Part 7: Diffie-Hellman Key Exchange
Part 8: RSA Encryption
For more, visit their website.