BLOCK CIPHER
INPUT - a block of plaintext bits, key
PROCESS - perform series of operations
OUTPUT - a block of cyphertext bits
Properties
Plaintext Block size is fixed
Cyphertext Blocksize is also fixed
Block size too short (dictionary attacks) and too large can cause issues like padding of spaces unused in the black

Versatility - widely used, primitives like MAC and hash functions
Compatibility - since used in many places, easily compatible like AES
Adaptability

PROBLEMS of PADDING
introduces inefficiency, e.g. padding 8 bit in a 128-bit AES scheme
can cause security issue if a proper padding scheme is not chosen

DES -> 64 bits block
AEX -> 128 bits block

	Created by Bhagya Prasad over 11 years ago

MSc Cryptography Note on SYMMETRIC ENCRYPTION, created by Bhagya Prasad on 11/05/2013.