Master Caesar Cipher & Substitution Techniques | Cryptography Series 🔐

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Playfair Substitution Cipher https://youtu.be/w_xr7pj-O6c

Monoalphabetic Substitution Cipher https://youtu.be/Hw1T7GOnVW0

Caesar Cipher | Caesar Substitution Cipher https://youtu.be/2N9GlhysYJw


PlayList : Cryptography and Network Security : https://www.youtube.com/playlist?list=PLhwpdymnbXz7hvvqhqjIIG4tEdhAgQqll

The Caesar cipher is one of the earliest known and simplest ciphers.
It is a type of substitution cipher in which each letter in the plaintext is 'shifted' a certain number of places down the alphabet.
For example, with a shift of 1, A would be replaced by B, B would become C, and so on.
The method is named after Julius Caesar, who apparently used it to communicate with his generals.
The algorithm can be expressed as
For each plaintext letter p , substitute the ciphertext letter C
C = E(k, p) = (p + k) mod 26
Where k takes on a value in the range 1 to 25.
The decryption algorithm is simply
p = D(k, C) = (C - k) mod 26
Drawbacks - Caesar Cipher is one of the weakest forms of encryption as
The key space is very small. Using a brute force attack method, one could easily try all (25) possible combinations to decrypt the message without initially knowing the key.
The language of the plaintext is known and easily recognizable.

Cryptanalysis: Cryptanalytic attacks rely on the nature of the algorithm plus perhaps some knowledge of the general characteristics of the plaintext or even some sample plaintext–ciphertext pairs.

Brute-force attack: The attacker tries every possible key on a piece of ciphertext until an intelligible translation into plaintext is obtained. On average, half of all possible keys must be tried to achieve success.

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