C Flashcards
What describes the modulo operation
It is the remainder of the division
How modulo work
المقسوم ينضرب بالناتج والمتبقي هو الناتج لل modula
Fiestel cipher
Breaks the designing to design a good key expansion and a round function
AES SIZE
128,192,256 bits
A fact about the AES
The key size is secured for the future to be used
Why is DES no longer recommended for use
Key is too short
Least advisable padding scheme
Pad the message with all zeros
AES MODES
ECB(Electronic code book )
CBC(cipher block chaining )
CFB(cipher feedback mode)
OFB(output feedback mode)
CTR(counter mode)
GCM(galois counter mode)
Encrypts each block of plaintext independently with the same key
ECB
Each plaintext is XORed with the previous cipher textblock before encryption
CBC
Converts a block cipher into a stream cipher
CFB
Similar to CFB but uses encrypted IV as a key stream
OFB
A counter value is encrypted to generate a key stream
CTR
ECB features
Simple, insecure
CBC features
Chaining prevents repetition
CFB features
Stream cipher mode
OFB features
Stream cipher mode, error tolerant
CTR features
Parallesziable, efficient
GCM features
Encryption + authentication
Evaluation criteria
Cost
Security
Implementation and algorithm
A simple mono alphabetic cipher has how many outcomes
26!
Caesar cipher requires
Shifts the key is in the shift
AES finalists
MARS
RC6
Rijndael
Serpent
Twofish
Examples of block ciphers
AES
DES
3DES
