Cryptography is broadly classified into two categories: Symmetric key Cryptography and Asymmetric key Cryptography (popularly known as public key cryptography).

Now Symmetric key Cryptography is further categorized as Classical Cryptography and Modern Cryptography.

Further drilling down, Classical Cryptography is divided into Transposition Cipher and Substitution Cipher. On the other hand, Modern Cryptography is divided into Stream Cipher and Block Cipher.

So, let’s understand these algorithms with examples.