Flashcards
Cryptography 2
Cards in this deck (24)
- 1What is the importance of models and definitions?Models and definitions aid understanding of the task to be achieved
- 2What do threat models and security definitions enable?Evaluation and comparison of schemes
- 3What does a "clear" threat model and security definition allow?Understanding of the security guarantees provided by the scheme
- 4A clear threat model and security definition enables...schemes to be used as components of a larger system (scheme modularity)
- 5Cryptography currently requires 4 computational assumptions, one of which is... (1)1. Allowing researchers to validate the assumption
- 6Cryptography currently requires 4 computational assumptions, which are... (2)2. Allowing meaningful comparison between schemes based on different assumptions
- 7Cryptography currently requires 4 computational assumptions, which are... (3)3. Practical implications in case assumptions are wrong
- 8Cryptography currently requires 4 computational assumptions, which are... (4)Enabling proofs for security
- 9Skytale is an example of a...transposition cipher
- 10In a transposition cipher, what is kept the same and what is changed?Letters are not changed, but letter order IS changed
- 11The Caesar cipher is an example of a...substitution cipher
- 12In a substitution cipher, what is kept the same and what is changed?Letters are changed but their order remains the same
- 13When using modular arithmetic what are we looking for?The number that occurs as a remainder when one number is divided by another
- 148 mod 3 = ?2
- 15means...the elements from {0...N-1}
- 16(CAN...)Can be used to identify the alphabet in which A=0 ... Z=25
- 17The caesar cipher has a shift amount of...3
- 1825 = 35 mod 10 why is this correct?(25-35) = 10 which can be cleanly divided by 10
- 1925 != (35 mod 10) why is this correct?(35 mod 10) = 5
which is not equal to 25 - 205 = (35 mod 10) why is this correct?(35 mod 10) = 5
which is equal to 5 - 21Ring of Congruence Example [3] + [4] = [7] = [2] {... -8, -3, 2, 7 ... } What is the significance of Z5?ZN is the N that we use to divide... in this case 5
![Ring of Congruence Example [3] + [4] = [7] = [2] {... -8, -3, 2, 7 ... } What is the significance of Z5?](https://examtimeassets.s3.amazonaws.com/uploads/media/image/14824080/desktop_fbebbdda-fdd9-48eb-94a2-2002ffff3b98.png)
- 22ROT13 is an X that has a key of Yshift cipher that has a key of 13
- 23The Vigenere cipher is...polyalphabetic
- 24The Vigenere cipher applies...several substitution ciphers with different keys to different text positions