18 Questions
What is the decryption process used by Bob to decrypt the message?
Computing A^-1ci(mod 26) for each ciphertext block ci
What is the numerical substitution used in the Hill cipher example?
a b c d e f g h i j k l m n o p q r s t u v w x y z = 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
What is the result of encrypting the plaintext 'pay' using the Hill cipher with the encryption key?
C = 'LNS' when P = 'pay'
What is the property of the matrix used in the Hill cipher encryption key?
Invertible
What is the purpose of the inverse key in the Hill cipher decryption process?
To decrypt the ciphertext
What is the block size used in the Hill cipher example?
n = 2
What is the main advantage of using polyalphabetic ciphers over substitution ciphers?
Polyalphabetic ciphers make frequency analysis much more difficult in order to crack the code.
How does the Vigenere cipher work?
The Vigenere cipher uses successively shifted alphabets, with each letter of the keyword determining the shifted alphabet used in the encoding process.
What is a polyalphabetic substitution cipher?
A polyalphabetic substitution cipher uses a separate monoalphabetic substitution cipher for each successive letter of plaintext, depending on a key.
How is the Vigenere tableau used in the encoding process?
The Vigenere tableau is used to determine the shifted alphabets used in the encoding process, based on the letters of the keyword.
What is the purpose of the keyword in the Vigenere cipher?
The keyword determines the shifted alphabets used in the encoding process.
What is an example of a polyalphabetic cipher?
The Vigenere cipher is an example of a polyalphabetic cipher.
What is the process of assigning numerical values to characters in the Hill cipher, and what is the range of values?
The process is called numerical substitution, and each character is assigned a numerical value from 0 to 25 (a=0, b=1,…z=25).
What is the role of the matrix K in the Hill cipher, and what are its dimensions?
The matrix K represents the encryption key, and it is a 3x3 matrix.
What is the general formula for encrypting a plaintext block in the Hill cipher?
Ci = APi (mod 26) for each plaintext block pi.
What is a necessary property of the matrix A in the Hill cipher, and why is it important?
The matrix A must be invertible, and it is important because it allows for decryption.
What is the purpose of dividing the plaintext into blocks in the Hill cipher, and what is the relationship between the block size and the matrix dimensions?
The plaintext is divided into blocks of n letters, and the matrix A is an n x n matrix.
What is the role of modular arithmetic in the Hill cipher, and what is the modulus used?
Modular arithmetic is used to reduce the results of the matrix multiplication to a range of 0 to 25, and the modulus is 26.
Practice decrypting messages using Hill Cipher with these examples. Compute A-1ci(mod 26) to decrypt ciphertext blocks. Learn cryptography with these step-by-step examples.
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