Cryptographic Solutions

Question 1

Cryptography

Answer 1

Practice and study of writing and solving codes
- Encryption to hide information’s true meaning

Question 2

Algorithm (Cipher)

Answer 2

Performs encryption or decryption

• MD5
• SHA Family
• RIPEMD
• HMAC

Question 3

Key

Answer 3

Essential for determining cipher output

• example: ROT13

Question 4

Key Length

Answer 4

Proportional to security
- longer key = higher security

Question 5

Key Rotation

Answer 5

Best practice for security longevity

Question 6

Symmetric Algorithms

Answer 6

• DES
• Triple DES
• IDEA
• AES
• Blowfish
• Twofish
• Rivest Cipher

Question 7

Asymmetric Algorithms

Answer 7

• Diffie-Hellman
• RSA
• Elliptic Curve Cryptography

Question 8

Symmetric Encryption

Answer 8

Uses a single key for both encryption and decryption
- Often referred to as private key encryption
- requires both sender and receiver to share the same secret key
- Offers confidentially but lacks non-repudiation
- Challenges with key distribution in large-scale usage because more people = more sharing of the keys

Question 9

Asymmetric Encryption (Public Key Cryptography

Answer 9

Uses two separate keys
Public key for encryption/private key for decryption
- no need for shared keys
- slower compared to symmetric encryption but solves key distribution challenges

Commonly used algorithms:
- Diffie-Hellman
- RSA
- Elliptic Curve

Question 10

Hybrid Approach

Answer 10

Combines both symmetric and asymmetric encryption for optimal benefits
- asymmetric encryption used to encrypt and share a key
- symmetric encryption used for bulk transfer, leveraging the shared secret key
- offers security and efficiency

Question 11

Stream Cipher

Answer 11

Encrypts data bit-by-bit or byte-by-byte in a continuous stream
- uses a keys tram generator and exclusive XOR function for encryption
- suitable for real-time communication data streams like audio and video
- often used in symmetric algorithms

Question 12

Block Cipher

Answer 12

Breaks input data into fixed-size blocks before encryption
- usually 64, 128, or 256 bits at a time

Padding added to smaller data blocks to fit the fixed block size
- advantages include ease of implementation and security
- can be implemented in software, whereas stream ciphers are often used in hardware solutions

Question 13

Data Encryption Standard (DES)

Answer 13

• 64-bit key (56 effective bits due to parity)
• Encrypts data in 64-bit blocks through 16 rounds of transposition and substitution
• widely used from the 1970s to the early 2000s

Question 14

Triple DES (3DES)

Answer 14

Utilizes three 56-bit keys
1. First key - encrypts
2. Second key - decrypts
3. Third key - encrypts

• provides 112-bit key strength but is slower than DES

Question 15

International Data Encryption Algorithm (IDEA)

Answer 15

A symmetric block cipher with a 64-bit block size
- Uses a 128-bit key
- Faster and more secure than DES
= not as widely used as AES

Question 16

Advanced Encryption Standard (AES)

Answer 16

Symmetric
Replaced DES and 3DES as the US government encryption standard
- Supports 128-bit, 192-bit, or 256-bit keys and matching block sizes
- widely adopted and considered the encryption standard for sensitive unclassified information

Question 17

Blowfish

Answer 17

Symmetric
A block cipher with key sizes ranging from 32 to 448 bits
- developed as a DES replacement but not widely adopted

Question 18

Twofish

Answer 18

Symmetric
A block cipher supporting 128-bit block size and key sizes of 128, 192, or 256 bits
- open source and available for use

Question 19

RC Cipher Suite (RC4, RC5, RC6)

Answer 19

Symmetric
Created by cryptographer, Ron Rivest
- RC4 is a stream cipher with variable key sizes from 40 to 2048 bits, used in SSL and WEP
- RC5 - a block cipher with key sizes up to 2048 bits
- RC6 - Based on RC5, was considered as a DES replacement