24 Questions
Cryptography is the art and science of keeping messages public.
False
Decryption is the process of encoding the contents of a message.
False
Cryptanalysis is the art of breaking ciphers.
True
Symmetric key encryption uses different keys for encryption and decryption.
False
Cryptographers are people who practice cryptanalysis.
False
Public-key encryption is a type of symmetric key encryption.
False
Asymmetric Key Encryption uses only one key for both encryption and decryption.
False
Public-key cryptography allows anyone to decrypt a message.
False
Substitution cipher replaces each element of the plaintext with a different element in the alphabet.
True
Monoalphabetic ciphers use different substitutions across the entire message.
False
Vigenère cipher is an example of a polyalphabetic cipher.
True
Product cipher is classified as a transposition cipher.
False
The Playfair Cipher is a monoalphabetic cipher.
False
In the Caesar cipher, each letter is replaced by the letter one position further down the alphabet.
False
The Vigenère Cipher is a polyalphabetic substitution cipher.
True
The keyword 'LEMON' was used to encrypt the plaintext 'ATTACK AT DAWN' in the Vigenère Cipher.
True
In the Caesar cipher, decryption formula is p = (c - k) mod 26.
True
The Vigenère Cipher uses a table together with a keyword for encryption and decryption.
True
In Playfair Cipher, if there is a repeated letter in a pair, a filler like 'Z' is inserted.
False
In Playfair Cipher, if both letters of a pair fall in the same row, they are replaced with the letter above them.
False
In Playfair Cipher, if both letters of a pair fall in the same column, they are replaced with the letter below them.
True
Row Transposition Ciphers involve shuffling the plaintext without altering the actual letters used.
True
Rail Fence cipher involves writing message letters out diagonally over a number of columns.
False
In Rail Fence cipher, if the depth is 3, the ciphertext is read off vertically instead of row by row.
False
Study Notes
Cryptography Basics
- Cryptography is the art and science of keeping messages secret, not public.
Encryption and Decryption
- Decryption is the process of decoding the contents of a message, not encoding.
- Symmetric key encryption uses the same key for both encryption and decryption.
- Asymmetric Key Encryption, also known as public-key encryption, uses a pair of keys: one for encryption and another for decryption.
Cryptanalysis
- Cryptanalysis is the art of breaking ciphers, not making them.
Cryptographers
- Cryptographers are people who practice cryptography, not cryptanalysis.
Ciphers
Substitution Ciphers
- Substitution cipher replaces each element of the plaintext with a different element in the alphabet.
- Monoalphabetic ciphers use a single substitution across the entire message.
- Polyalphabetic ciphers use multiple substitutions.
- Vigenère cipher is an example of a polyalphabetic cipher.
Transposition Ciphers
- Product cipher is classified as a transposition cipher.
- Row Transposition Ciphers involve shuffling the plaintext without altering the actual letters used.
- Rail Fence cipher involves writing message letters out diagonally over a number of columns.
Specific Ciphers
Playfair Cipher
- The Playfair Cipher is a monoalphabetic cipher.
- In Playfair Cipher, if there is a repeated letter in a pair, a filler like 'Z' is inserted.
- In Playfair Cipher, if both letters of a pair fall in the same row, they are replaced with the letter above them.
- In Playfair Cipher, if both letters of a pair fall in the same column, they are replaced with the letter below them.
Vigenère Cipher
- The Vigenère Cipher is a polyalphabetic substitution cipher.
- The Vigenère Cipher uses a table together with a keyword for encryption and decryption.
- The keyword 'LEMON' was used to encrypt the plaintext 'ATTACK AT DAWN' in the Vigenère Cipher.
Caesar Cipher
- In the Caesar cipher, each letter is replaced by the letter one position further down the alphabet.
- In the Caesar cipher, decryption formula is p = (c - k) mod 26.
Learn about polygraphic ciphers, specifically focusing on the Playfair and Caesar cipher. Understand how the Playfair cipher substitutes two-letter groups, and how the Caesar cipher shifts each letter by a fixed number of positions.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
