Master Monoalphabetic Substitution Cipher: Easy Cryptography Tutorial 🔐

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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

A substitution technique is one in which the letters of plaintext are replaced by other letters or by numbers or symbols.1 If the plaintext is viewed as a sequence of bits, then substitution involves replacing plaintext bit patterns with ciphertext bit patterns.
Instead, the “cipher” line can be any permutation of the 26 alphabetic characters,
Then there are 26! or greater than 4x1026 possible keys.
This is 10 orders of magnitude greater than the key space for DES and would seem to eliminate brute-force techniques for cryptanalysis.
Such an approach is referred to as a monoalphabetic substitution cipher,
Because a single cipher alphabet (mapping from plain alphabet to cipher alphabet) is used per message.
A Monoalphabetic substitution cipher, relies on a fixed replacement structure.
The substitution is fixed for each letter of the alphabet.
Thus, if "a" is encrypted to "R", then every time we see the letter "a" in the plaintext, we replace it with the letter "R" in the ciphertext.
If the cryptanalyst knows the nature of the plaintext (e.g., noncompressed English text), then the analyst can exploit the regularities of the language.

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