Key management involves the generation, exchange, storage, use, and replacement of cryptographic keys within a cryptosystem, addressing the entire key lifecycle to combat threats such as key compromise. Techniques include symmetric and public-key encryption, with notable algorithms like the Diffie-Hellman key exchange introduced in 1976 for secure key exchange. Digital certificates serve as identity documents that bind public keys to individuals or organizations, validated by certification authorities to facilitate secure communications.

1. Key Management
cryptography

2. What is Key Management?
★ Key management is the management of cryptographic keys in a
cryptosystem.
★ This includes dealing with the generation, exchange, storage, use, and
replacement of keys.
★ It includes cryptographic protocol design, key servers, user procedures,
and other relevant protocols.
★ It deals with entire key lifecycle.

3. Why are we talking about key management?
★ With the rise of Cybercrime, companies are investing significant amounts
in Information Security in order to protect themselves, their employees and
partners, but in the end that might not be enough.
★ Threats:
○ compromise of confidentiality of secret keys
○ compromise of authenticity of secret or public keys.
○ unauthorized use of public or secret keys

4. Key management techniques
a)Symmetric-key encryption:

5. Key management techniques
b)Public-key
encryption:

6. Key LifeCycle

7. Distribution of
Public Keys
★ Public announcement
★ Publicly available
directory
★ Public-key authority
★ Public-key certificates

8. Public announcement

9. Publicly available
directory

10. Public-key
authority

11. Public-key certificates

12. Diffie Hellman key exchange algorithm
★ First public key algorithm proposed by Diffie and Hellman in 1976.
★ Used only for key exchange
★ Used In many commercial products

13. All users agree on two parameters 1) large prime number q 2)
primitive root a
each user (eg. A) generates their key:
chooses a secret key(number):
xA < q
compute their public key:
yA = a^xA mod q
public keys are stored in universal directory
Algorithm:

14. shared session key for users A & B is KAB:
KAB = axA.xB mod q
= yA^xB mod q (which B can compute)
= yB^xA mod q (which A can compute)
KAB is used as session key in private-key encryption scheme between Alice and Bob
if Alice and Bob subsequently communicate, they will have the same key as before,
unless they choose new public-keys
Disadvantage:
1)man in the middle attack
2) authentication is needed
Algorithm:

15. Digital Certificate

16. Digital Certificate
★ A digital identity document binding a public key to a specific person or
organization
★ Certification Authorities are the digital world’s equivalent to passport
offices. They issue digital certificates and validate holders’ identity and
authority

17. What is the Process of obtaining a
certificate?

18. How do You Obtain An Individual’s Public
Key?

19. How Digital Certificates are Used for
Message Encryption?

20. X.509 Certificates

21. In Chrome, Settings->Advanced Setting->Manage Certificates

22. In Wireshark, SSL packets captured

23. Thank You