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Questions and Answers
What is the modern definition of cryptography?
What is the modern definition of cryptography?
In cryptography, what is the purpose of a shared key?
In cryptography, what is the purpose of a shared key?
According to Kerckhoffs' Principle, where does the security of a cryptographic system rely?
According to Kerckhoffs' Principle, where does the security of a cryptographic system rely?
Why is it easier to keep a short key secret than to keep an algorithm secret?
Why is it easier to keep a short key secret than to keep an algorithm secret?
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What is the key space size for the shift cipher?
What is the key space size for the shift cipher?
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What does the notation $[a mod N]$ denote?
What does the notation $[a mod N]$ denote?
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What attack involves trying every possible key?
What attack involves trying every possible key?
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What is the necessary condition for security in an encryption scheme?
What is the necessary condition for security in an encryption scheme?
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What is the size of the key space for the mono-alphabetic substitution cipher?
What is the size of the key space for the mono-alphabetic substitution cipher?
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What method is used for attacking the Vigenère cipher?
What method is used for attacking the Vigenère cipher?
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What does the key define in the shift cipher?
What does the key define in the shift cipher?
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What is the encryption method for the Vigenère cipher?
What is the encryption method for the Vigenère cipher?
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What attack works against the mono-alphabetic substitution cipher?
What attack works against the mono-alphabetic substitution cipher?
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What is the necessary condition for a secure encryption scheme?
What is the necessary condition for a secure encryption scheme?
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What is the encryption method for the mono-alphabetic substitution cipher?
What is the encryption method for the mono-alphabetic substitution cipher?
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What is the size of the key space for the shift cipher?
What is the size of the key space for the shift cipher?
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Study Notes
Cryptography Basics
- The modern definition of cryptography is not provided, but the term generally refers to the practice and study of techniques for secure communication.
Shared Key
- The purpose of a shared key in cryptography is to enable secure communication between parties.
Kerckhoffs' Principle
- The security of a cryptographic system relies on the secrecy of the key, not the secrecy of the algorithm.
Key Secrecy
- It is easier to keep a short key secret than to keep an algorithm secret because an algorithm is a complex system that may be reverse-engineered or analyzed, whereas a short key is a single piece of information.
Shift Cipher
- The key space size for the shift cipher is 26, since there are 26 possible shifts.
- The key in the shift cipher defines the number of positions each letter is shifted.
Modular Arithmetic
- The notation $[a mod N]$ denotes the remainder of $a$ when divided by $N$.
Brute Force Attack
- A brute force attack involves trying every possible key to decipher the encrypted data.
Security Condition
- The necessary condition for security in an encryption scheme is that an unauthorized party should not be able to determine the plaintext from the ciphertext without knowledge of the key.
Mono-Alphabetic Substitution Cipher
- The key space size for the mono-alphabetic substitution cipher is 26!, since there are 26! possible permutations of the alphabet.
- The encryption method for the mono-alphabetic substitution cipher involves replacing each plaintext letter with a corresponding ciphertext letter based on a fixed permutation of the alphabet.
- A frequency analysis attack works against the mono-alphabetic substitution cipher, which involves analyzing the frequency of letters in the ciphertext to determine the permutation.
Vigenère Cipher
- The encryption method for the Vigenère cipher involves using a series of Caesar ciphers with different shifts for each letter, based on a keyword.
- A frequency analysis attack is used for attacking the Vigenère cipher.
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Description
Test your knowledge of cryptography with this quiz! Explore the history and modern applications of mathematical techniques used to secure digital information and systems against adversarial attacks. Learn about key concepts, encryption methods, and more.
