What does key +3 mean in Caesar cipher?

The Caesar cipher shifts each letter of the plain text by an amount specified by the key. For example, if the key is 3, each letter is shifted three places to the right. Example of how a Caesar cipher works.

What is a Hill cipher?

In classical cryptography, the Hill cipher is a polygraphic substitution cipher based on linear algebra. Invented by Lester S. Hill in 1929, it was the first polygraphic cipher in which it was practical (though barely) to operate on more than three symbols at once.

How do you shift a Cypher?

The shift cipher encryption uses an alphabet and a key (made up of one or more values) that shifts the position of its letters. A letter in position N in the alphabet, can be shifted by X into the letter located at position N+X (This is equivalent to using a substitution with a shifted alphabet).

How do you decode a Hill cipher?

Decrypting with the Hill cipher is built on the following operation: D(K, C) = (K-1 *C) mod 26 Where K is our key matrix and C is the ciphertext in vector form. Matrix multiplying the inverse of the key matrix with the ciphertext produces the decrypted plaintext.

Why is Hill cipher important?

The Hill cipher is a block cipher that has several advantages such as disguising letter frequencies of the plaintext, its simplicity because of using matrix multiplication and inversion for encryption and decryption, and its high speed and high throughput [3].

How do you decode a hill Cypher?

To decrypt hill ciphertext, compute the matrix inverse modulo 26 (where 26 is the alphabet length), requiring the matrix to be invertible. Decryption consists in encrypting the ciphertext with the inverse matrix. Note that not all matrices can be adapted to hill cipher.

How is Hill cipher calculated?

Hill Cipher example 2×2 decryption

  1. Step 1: Calculate the multiplicative inverse for the determinant.
  2. Step 2: Value for Adjugate Matrix.
  3. Step 1: Calculating the multiplicative inverse for the Determinant.
  4. Step 2: Calculate the Adjugate Matrix.
  5. Step 3: Finalising the inverse matrix value.