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WorksheetsClassical Cryptography Challenge
Total questions: 25
Worksheet time: 25mins
What is the key shift in a Caesar cipher if the key is 3?
3 positions diagonal in the alphabet
1 position forward in the alphabet
3 positions forward in the alphabet
3 positions backward in the alphabet
Which cipher uses a keyword to determine the letter substitution?
Caesar cipher
Vigenère cipher
Transposition cipher
Substitution cipher
In a Vigenère cipher, what is the length of the repeating key if the key is 'KEY'?
5
4
3
2
What is the main characteristic of a Vernam cipher?
It encrypts data using a fixed key.
It uses a one-time pad for encryption.
It uses a symmetric key for encryption.
It relies on a public key infrastructure.
Which cipher is considered unbreakable when used correctly?
Caesar cipher
RSA encryption
Vigenère cipher
one-time pad
In a Playfair cipher, how are duplicate letters handled?
Duplicate letters in a digraph are handled by replacing the second letter with a filler letter, usually 'X'.
Duplicate letters are combined into a single letter.
Duplicate letters are ignored entirely.
Duplicate letters are replaced with the next letter in the alphabet.
What is the primary method of encryption in a Rail Fence cipher?
Zigzag pattern across multiple rails
Substitution of letters
Straight line encryption
Transposition of words
How many rows are used in a Rail Fence cipher with a depth of 3?
5
3
2
4
What is the formula for the number of possible keys in a one-time pad?
n!
2^n
n^2
2n
In an Autokey cipher, what is the role of the plaintext?
The plaintext is used to generate the keystream for encryption.
The plaintext is used to create a static key for encryption.
The plaintext serves as the final output of the cipher.
The plaintext is encrypted directly without modification.
What is the main advantage of using a Polybius square in encryption?
It relies on a single key for all messages.
It requires complex algorithms for encryption.
It simplifies the encryption and decryption process.
It is only effective for numeric data.
How does the Row Transposition cipher rearrange the plaintext?
The Row Transposition cipher organizes the plaintext by sorting it alphabetically.
The Row Transposition cipher encrypts the plaintext by substituting letters with numbers.
The Row Transposition cipher rearranges the plaintext by reading it backwards.
The Row Transposition cipher rearranges the plaintext by writing it into a grid and reading the columns.
What is the maximum key length for a Vernam cipher?
The maximum key length is 256 bits.
The maximum key length is 128 characters.
The maximum key length is equal to the length of the plaintext.
The maximum key length is fixed at 64 bytes.
In a Playfair cipher, how many letters are in the alphabet used?
26
24
25
30
What is the output of a Caesar cipher with the plaintext 'HELLO' and a key of 5?
MJQQT
KHOOR
IFMMP
GDKKN
How does the Rail Fence cipher encode the message 'HELLO WORLD'?
HLOORLELWD
HLODLERWL
HELLO WRLD
HLOELRLDW
What is the main disadvantage of the Caesar cipher?
It is too complex for basic encryption.
It is easily broken due to its simplicity and fixed shift.
It requires a key for every letter.
It can only be used with numbers.
In a Vigenère cipher, what happens if the key is shorter than the plaintext?
The key is used only once for the entire plaintext.
The key is truncated to fit the plaintext.
The key is repeated to match the length of the plaintext.
The key is ignored completely.
What is the purpose of the keyword in a Playfair cipher?
The keyword is used to generate the key matrix for encryption and decryption.
The keyword is used to create a random sequence of letters.
The keyword serves as a password for user authentication.
The keyword is only relevant for the decryption process.
What is the primary function of the key in a Vigenère cipher?
The key is irrelevant to the encryption process.
The key is used to determine the shift for each letter in the plaintext.
The key is used to encrypt the plaintext directly without modification.
The key serves as a static reference for decryption only.
In a Playfair cipher, how are the letters arranged in the key matrix?
Letters are arranged based on the frequency of their occurrence.
Letters are arranged randomly without repetition.
Letters are arranged in pairs to form digraphs.
Letters are arranged in alphabetical order.
What is the main advantage of using a substitution cipher over a transposition cipher?
Substitution ciphers are easier to implement.
Substitution ciphers provide better security against frequency analysis.
Substitution ciphers do not require a key.
Substitution ciphers can encrypt longer messages more efficiently.
What is the main function of the key in a substitution cipher?
The key is irrelevant and does not affect the encryption.
The key is used to generate a random sequence of letters.
The key is only necessary for decryption.
The key determines the specific letter substitutions used in the encryption process.
In a transposition cipher, how is the plaintext typically rearranged?
By writing the plaintext in rows and then reading it in a different order.
By reversing the order of the letters.
By substituting letters with numbers based on their position.
By applying a fixed shift to each letter.
What is the primary advantage of using a one-time pad for encryption?
It is faster than other encryption methods.
It can encrypt data without the need for a key.
It provides perfect secrecy when used correctly.
It is easy to implement and understand.
