4.2 - Encryption

Question 1

What is encryption?

Answer 1

Commonly used to protect the confidentiality of data in transit and at rest

Question 2

What is Symmetric encryption and the process?

Answer 2

Uses the same key to encrypt and decrypt

Also known as single key, secret key, session key, encryption

Process
Cleartext -> symmetric algorithm + symmetric key -> ciphertext -> symmetric algorithm + symmetric key -> Cleartext

Question 3

What is DES (symmetric algorithm)?

Answer 3

Block cipher
64 bit key/16 rounds of substitution and transposition
- Established in 1997
Can be broken in less than 56 hours

Question 4

What is 3DES (symmetric algorithm)?

Answer 4

Block cipher
64 bit key 48 rounds of substitution, transposition using 2/3 keys

• 1999 became US gov standard
• Considered deprecated (outdated/weak)

Question 5

What is AES/Rijndael (symmetric algorithm)?

Answer 5

Block cipher

128/192/256 bit key
10/12/14 rounds of substitution and transposition

• 2002 replaces 3DES as US gov standard

Question 6

What is RC4 (symmetric algorithm)?

Answer 6

Stream cipher

key sizes 10-2048
- 4 variants:
SPRITZ
RC4A
VMPC
RC4A+

Question 7

What are the characteristics of symmetric encryption?

Answer 7

Processing - computationally efficient

Key size - generally 128, 192, 256 bits

Scalability - not scalable -> need to create new keys for every individual

Key exchange - inherently insecure

Question 8

What is Asymmetric encryption?

Answer 8

Uses two mathematically related keys to encrypt and decrypt. Public and private keys. Public key is freely distributed. Private key must be secured only used by owner

Question 9

What is RAS (Asymmetric algorithm)?

Answer 9

Widely implemented de facto commercial standard

Works with encryption and digital signatures

Question 10

What is Elliptic curve cryptosystem - ECC (Asymmetric algorithm)?

Answer 10

Similar to RSA but smaller key sizes (requires less computing power)

Current US Gove standard

Question 11

What is Diffie-Hellman (Asymmetric algorithm)?

Answer 11

Used for key agreement (key exchange)

Allows two parties in the same DH group that have no prior knowledge of each other jointly establish a shared secrect key

Question 12

What is EL Gamal (Asymmetric algorithm)?

Answer 12

Primarily used for transmitting digital signatures and key exchanged

Question 13

What are asymmetric encryption characteristics?

Answer 13

Processing - Computationally intensive

Key size - generally 2048 or greater

Scalability - is scalable

Key exchange - designed for key exchange

Question 14

What is key management practives statement (KMPS)?

Answer 14

A document that describes in detail the organisational structure, the responsible roles and the rules for key management