18.5. Conclusion

Try these first

1. 1.

   What is symmetric key encryption?

   Hint

   Think about the lock and key analogy.

2. 2.

   Give an example of plaintext.

   Hint

   What does a message look like before it is scrambled?

3. 3.

   What type of encryption uses the same key for both encrypting and decrypting?

   • Asymmetrical Encryption
   • Symmetric Key Encryption
   • Hash Encryption

   Hint

   Think of the lock and key analogy.

4. 4.

   Is it possible for two parties to establish a common key over a public channel?

   • True
   • False

   Hint

   What did we learn about Diffie and Hellman's contributions?

5. 5.

   Explain how an attacker might try to break symmetric key encryption and what measures can be taken to protect against such attacks.

   Hint

   Consider what makes a key difficult to guess.

6. 6.

   Using what you've learned about Diffie-Hellman, create a simplified example step-by-step showing how Sita and Ram agree on a key.

   Hint

   Focus on the steps needed for agreement and remind yourself of what they exchange.