Presentation Layer Question Pool

1. Fill in the blank:
   ASN.1 is an example of a _______________ layer protocol.
2. ASN.1 is similar to:
   • RPC
   • RFS
   • XDR
   • TCP
3. In the context of encryption, a signature provides:
   • assurance that only the designated receiver could read the message.
   • a key for encrypting special messages.
   • assurance that only the designated sender could have sent the message.
   • a way to correct errors in the message.
4. The purpose of data compression is:
   • to reduce the number of zeros in the bit stream.
   • to use less bandwidth while providing a still recognizable picture.
   • to reduce the number of bits transmitted for a given message.
   • to reduce the number of ones in the bit stream.
5. Which of the following is not a component of our encryption model?
   • Algorithm
   • Key(s)
   • Key Distribution Center
   • Plaintext
   • Listeners
6. Single pass encryption or compression schemes are less important to file storage systems than data communications because:
   • Speed is less important.
   • it isn't. The statement is not true.
   • two pass systems are easier to use on packets
   • the end to some messages isn't known at the start.
7. A major disadvantage to public key encryption systems is:
   • few people understand the algorithm.
   • complexity of the calculations.
   • that everyone can send you encrypted messages.
   • key distribution.
8. The simplest data compression method {on this list} is:
   • LZ
   • Huffman
   • RLE
   • LZW
9. What are the three major functions of the Presentation layer?
10. A major problem in any encryption system is:
    • key distribution.
    • key sharing.
    • understanding the math.
    • secure paths for encrypted messages.
11. In the OSI model, which layer handles message encryption?
    • Security
    • Presentation
    • Data
    • Application
12. A public key cryptography system
    • means anyone can read your message.
    • uses two keys.
    • is more secure than private key systems.
    • is less secure than private key systems.
13. NFS uses what Presentation layer protocol:
    • RPC
    • XNS
    • XDR
    • UDP
14. Fill in the blank:
    XDR is an example of a ____________ layer protocol.
15. A public key cryptography system
    • means anyone can read your message.
    • uses two keys.
    • means you don't have to keep your key(s) secret.
    • is outdated by newer protocols like DES.
16. There are nine messages that an RSA encryption system cannot hide (i.e., encryption of the message yields the same message).
    T F (circle one)
17. Name and define MIME.
18. What is Lossy compression? What is an application it is useful in?
19. How many bits are used as the key in DES, the Data Encryption Standard?
20. Identify and explain the ONLY known 100% secure method of encryption.
21. Select the most effective encryption technique from the following:
    • Caesar cipher
    • MTV
    • Microsoft Word
    • RSA