Key Agreement and Loose ends

Question 1

RSA factoring record

Answer 1

2700 core years, which means 2700 PCs to crack in one year

Question 2

Agreeing Secret Key without meeting each other

Answer 2

Diffie and Heimman

Question 3

Diffie and Heimann secure parameters

Answer 3

1. prime p at least 1024 bits
2. use 1536 or 2048 bit prime p
3. special number p-1 has a super large prime factor with size almost size of prime p
4. prime p and prime q related by p-1 = 2q

Question 4

Key Management Considerations(8)

Answer 4

1. Key Generation
2. Key storage(sloppy?)
3. Key life cycle(regular?)
4. Number of people in charge of different keys(bribery)
5. Destruction/ zeroisation of keys
6. Key agreement
7. Key compromise
8. Key recovery

• often neglected
• easier to use keys to read than to decrypt

Question 5

Key Management Cheat Sheet (OWASP)

Answer 5

• guides developers in implementing cryptographic key management in app securely

Question 6

Key Storage

Answer 6

• never store in plaintext BUT in cryptographic vault like Hardware Security Module (HSM)
• keys have integrity protections applied in storage
• all key and cryptographic operation done in sealed vault