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How Cryptography Keeps The Internet Secure

Open Universiteit Nederland via Independent

This course may be unavailable.


The course starts with a simple introduction on writing secrets, revisiting the cryptographic techniques already used by the Romans and the Spartans. We will also see how to analyse such ciphertexts to discover the hidden secrets. We then will discuss somewhat more advanced cryptographic systems and discuss how to analyse these as well. The principles used by the Romans and Spartans together still form the underlying principles of modern-day cryptography, more specifically we will discuss two modern cryptographic systems (DES and AES) as an illustration.

The next part of the course is about public-key cryptography. You can think of this type of cryptography like padlocks: everyone with an open padlock can close the padlock, but you cannot open the padlock without the key. We will discuss two public-key cryptographic systems (RSA and ElGamal), and for those that have the guts, we will show you not just how, but also why they work.

The final part of the course is devoted to building security features out of cryptographic building blocks. We will discuss digital signatures, certificate chains, hash chains, etc..


  • Knowledge of the English alphabet
  • Ability to follow logic reasoning
  • Familiarity with high school maths




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