Lecture 8 Flashcards
cryptography and Symmetric key algorithms
A poly-alphabetic substitution cipher used in WWII by the Germans used a machine named what?
Enigma
A mono-alphabetic substitution does what?
Rotates the letters of the alphabet X places
A mono-alphabetic substitution cipher is susceptible to what?
frequency analysis
The 4 fundamental goals of cryptography are:
Confidentiality
Integrity
Authentication
Non-repudiation
What type of cryptography is used to provide confidentiality?
A. symmetric
B. asymmetric
C. either/both
C. either/both
Cryptographic algorithms rely upon _____ (crypto-variables)
keys
In private key, participants use what?
A. unshared keys (all participants have their own)
B. shared keys (all participants share a key)
B. shared keys (all participants share a key)
In public key, participants use what?
A. unshared keys (all participants have their own)
B. shared keys (all participants share a key)
A. unshared keys (all participants have their own) (public/private keys)
The art and science of creating and implementing secret codes and ciphers
cryptography
The study of methods to defeat codes and ciphers
crypanalysis
What are true of Kerchoff’s principle? select all that apply
A. they should be known and public
B. they should be kept secret
C. keys should remain private
D. weaknesses are unknown
A. they should be known and public
C. keys should remain private
In the AND operations, 1 is returned when what?
When both X and Y are 1.
In the OR operations, 1 is returned when what?
When at least X or Y is 1.
In XOR operations, 1 is returned when what?
When only X or Y is 1, but not both.
The _______ function is the remainder of the division of one number by another.
EX: 10 Mod 3 is 1
A. Division
B. Multiplicity
C. Modular
D. Modulo
D. Modulo
_____ occurs when the relationship between the plain text and the key is so complicated an attacker can’t continue altering the plain text and analyze to determine the key.
A. confusion
B. diffusion
C. encryption
A. Confusion
_____ occurs when a change in the plain text results in many changes spread throughout the cipher text.
A. confusion
B. diffusion
C. encryption
B. Diffusion
A nonce is what?
random number generator
_____ is when the information/privilege required to perform an operation is divided among multiple users.
A. shared knowledge
B. split knowledge
C. separated knowledge
B. split knowledge
What is M of N control?
the minimum number of agents (M) out of the total number of agents (N) work together to perform high security task.
The cryptographic strength is determined by measuring what?
The effort to break it
A _____ is a cryptographic system of symbols that represent words or phrases.
A. Code
B. Cipher
A. Code
A _____ is always meant to hide the true meaning of a message.
A. Code
B. Cipher
B. Cipher
A ____ cipher rearranges the letters of a plain-text message.
transposition
A ____ cipher uses an encryption algorithm to replace each character or bit of the plain-text message with a different one.
substitution
A _____ uses different substitution alphabet for each letter. It is a very long series of numbers.
one-time pad
A _____ cipher is as long as the message itself and it usually chosen from a common book.
running key (book)
A longer key usually provides what?
A. stronger encryption
B. weaker encryption
A. stronger encryption
Modern cryptographic system have a key size of at least what?
128 bit
Bulk encryption is primarily used with what type of cryptography?
Symmetric key (secret/private key cryptography)
What are true of symmetric key cryptography.
A. uses a small key B. needs a secure method of exchanging the key C. does not provide nonrepudiation D. scalable E. uses a large key F. fast
B. needs a secure method of exchanging the key
C. does not provide nonrepudiation
E. uses a large key
F. fast
What are true of asymmetric key cryptography.
A. it uses a private and public key B. provides nonrepudiation C. scalable D. fast E. difficult key revocation F. key distribution is simple
A. it uses a private and public key
B. provides nonrepudiation
C. scalable
F. key distribution is simple
A _____ transforms a variable-size input and returns a fixed-size string.
hashing algorithm
_____ is a 64-bit block cipher that has 5 modes of operation. The key is 56 bits long and uses XOR operations run through 16 times.
A. SHA
B. AES
C. PSK
D. DES
D. DES
_____ replaced DES and uses lengths and block sizes of 128, 192 and 256 bits.
A. SHA
B. AES
C. PSK
D. DES
B. AES
What are the 3 methods used to exchange secret keys securely.
Offline distribution
public key encryption
diffie-hellman key exchange algorithm
