Learn Hill Cipher Encryption & Decryption | Complete Guide with Example 🔐

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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


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Hill Cipher was Invented by Lester S. Hill in 1929
Like the other Digraphic Ciphers, it acts on groups of letters
Unlike the others it is extendable to work on different sized blocks of letters
Hill Cipher uses an area of mathematics called Linear Algebra
Some important concepts are used throughout: Matrix Multiplication, Modular Inverses, Determinants of Matrices, Matrix Adjugates
Hill cipher Encryption : Turn keyword into a key matrix (2x2 for Digraphs)
Turn the plaintext into digraphs
Turn each digraphs into a column vector.
Then perform matrix multiplication modulo 26 on each vector
These vectors are then converted back into letters to produce the ciphertext.
Hill cipher Decryption : Turn keyword into a Inverse key matrix (2x2 for Digraphs)
Turn the ciphertext into digraphs
Turn each digraphs into a column vector.
Then perform Inverse key matrix multiplication modulo 26 on each vector
These vectors are then converted back into letters to produce the plaintext.