A Cryptography Primer

Let's learn the basic idea of cryptography and look into some basic mechanisms behind the techniques mentioned in the previous lessons.

We'll cover the following...

Cryptography

One of the most central pieces in cryptography is the cipher.

Cipher

A cipher is an algorithm for converting a piece of data, called plaintext, into another piece of data, called ciphertext, which appears as random data and reveals no information about the original data.

We can also define a cipher as a pair of efficient algorithms $(E, D)$ where:

$E$ : $K \times M \to C$ is an encryption function receiving a plaintext (M) and a key (K) as an input and providing a ciphertext (C) as an output.
$D$ : $K \times C \to M$

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