40 Algorithms Every Programmer Should Know

Presenting Substitution Ciphers

Substitution ciphers have been in use for hundreds of years in various forms. As the name indicates, substitution ciphers are based on a simple concept—substituting characters in plain text with other characters in a predetermined, organized way.

Let's look at the exact steps involved in this:

1. First, we map each character to a substitute character.

2. Then, encode and convert the plaintext into cipher text by replacing each character in the plain text with another character in the ciphertext using substitution mapping.

3. To decode, bring back the plaintext by using substitution mapping.

Let's look at some examples:

• Caesar cipher:

In Caesar ciphers, the substitution mapping is created by replacing each character ...