Last time I said I would start discussing key tables. So let's do this. A key table is used to encrypt data. It is based on an original key. Other names for a key table are key setup or initialization. This is where some algorithms go wrong, and allow crackage.

The generation of random numbers is an integral part to encryption. So how exactly do you generate random numbers? When a computer does it, we call it the RNG (Random Number Generator). However there is a technique generate quasi-random numbers called PRNG, or Pseudo RNG. It allows you to "seed" the generator with a value. That value determines what numbers get generated. Every time you use the same seed, you get the same results.

Finally I want to go a little further with symmetric encryption algorithms. In particular, I want to mention a few implementations of symmetric encrption. The popular ones are DES, 3DES, and AES. However there is also IDEA and TwoFish. I will not go into the particulars of these right now. Perhaps we will review them next time.