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Chapter 2: Conventional/Symmetric Encryption Message Confidentiality,…
Chapter 2: Conventional/Symmetric Encryption Message Confidentiality
Conventional Encryption Principles
Basic terminology
plainttext
ciphertext
cipher
key
encipher (encrypt)
decipher (decrypt)
cryptography
type of operations
Substitution
Transportation
product
Number of key used
symmetric (single key)
asymmetric (two-key / public-key encryption)
way in which plaintext is processed
Block
Stream
cryptanalysis
Objective
to recover key not just messag
general approaches
cryptanalytic attack
brute-force attack
try every key
basic attack
assume either know / recognise plaintext
Classical Substitution Ciphers
Caesar Ciphers
Monoalphabetic Cipher
Playfair Cipher
Polyalphabetic Ciphers
Vigenere Cipher
Classical Transportation/Permutation Ciphers
Rail Fence cipher
Row Transposition Ciphers
Product Ciphers
Cryptanalytic Attacks
ciphertext only
known plaintext
chosen plaintext
chosen ciphertext
chosen text
more definitions
unconditional security
computational security
cryptology
Cipher Block Modes of Operation
Location of Encryption Devices
Conventional Encryption Principles
Plaintext
Encryption algorithm
Secret Key
Ciphertext
Decryption algorithm
Symmetric Encryption
Sender/Recipient share common key
Classical encryption
private-key
Requirements
Strong encryption algorithm
secret key known only to sender / receiver
Mathematically have: Y=Ek(X) and X=Dk(Y)
Assume encryption algorithm is known
Implies a secure channel to distribute key
Conventional / Private-key / Single-key