Αποτελέσματα Αναζήτησης
7 Μαρ 2023 · Decryption. In deciphering the ciphertext, we must perform the opposite (or inverse) functions on the ciphertext to retrieve the plaintext. Once again, the first step is to convert each of the ciphertext letters into their integer values. The decryption function is. D ( x ) = a^-1 ( x - b ) mod m.
As an example, let us encrypt the plaintext "affine cipher", using the key a = 5, b = 8. Firstly we must find the integer value of each of the letters in the plaintext alphabet (the standard alphabet of 26 letters in this case). The table below gives these values.
The affine cipher is a type of monoalphabetic substitution cipher, where each letter in an alphabet is mapped to its numeric equivalent, encrypted using a simple mathematical function, and converted back to a letter.
To encipher messages with the Affine cipher (or another cipher, see here for documentation): >>>from pycipher import Affine >>>Affine(a=5,b=9).encipher('defend the east wall of the castle') 'YDIDWYASDDJVAPJMMBIASDTJVAMD' >>>Affine(a=5,b=9).decipher('YDIDWYASDDJVAPJMMBIASDTJVAMD') 'DEFENDTHEEASTWALLOFTHECASTLE'
Affine cipher: Encode and decode . In affine cipher each letter in an alphabet is mapped to its numeric equivalent, encrypted using a simple mathematical function, and converted back to a letter. Each letter is enciphered with the function (ax + b) mod 26.
Our encryption and decryption mathematical formula provides the starting point for this mapping in the Affine Cipher. The alphabet's original letters work as the dictionary's keys, and their encrypted or decrypted versions act as the values.
Affine decryption requires to know the two keys A and B (the one from encryption) and the used alphabet. Example: Decrypt the ciphered message SNVSX with keys A=5 and B=3. For each letter of the alphabet, associate the value of its position in the alphabet.
