S A M P L E CPS 1 (Ramm) Fall 2003 12 November 2003 Quiz #10 Name ___________________ Honor Code________________________ Section _____ --------- A. Below are three examples of addressing in computer communications. Draw a line connecting the type to the example. Ethernet Address -- b0:40:95:0f:2b:7a Domain Address -- redstart.cs.duke.edu IP Address -- 152.3.140.145 C. True/False? 1) Every Ethernet controller in a local area network has the same address [False] 2) The telnet program is used to keep you from logging into remote computers [False] 3) When using the Ethernet, you are secure from all electronic eavesdropping [False] 4) The IP layer of the TCP/IP software used for Internet communications tries to make all networks look the same, regardless of underlying technology [True] 5) Due to the layering of software, packets are carried within packets (e.g. an IP packet is carried as data within an Ethernet packet) [True] 6) The only purpose of anonymus ftp is to hide the identity of the requester [False] 7) All access to information from a remote computer by way of the Internet requires an account and a password for that remote computer [False] 8) If a packet is found to be defective (using a checksum) the originating host must send it again. [True] 9) Communications packets are 100% efficient in that they contain only data [False] B. Decode the following text using the random number table (one time pad) shown below (The table contains only very small numbers to make your life easier). Someone else has encoded the message using this table. SHOW YOUR WORK! Answers only will get no credit! Z L F S M R W J E G P Z V U F Q H J X M C O 25 11 5 18 12 17 22 9 4 6 15 25 21 20 5 16 7 9 23 12 2 14 3 4 1 5 4 4 3 2 0 4 1 5 4 2 1 2 2 2 3 0 2 1 22 7 4 13 8 13 19 7 4 2 14 20 17 18 4 14 5 7 20 12 0 13 w h e n i n t h e c o u r s e o f h u m a n from "one time pad": 3 4 1 5 4 4 3 2 0 4 1 5 4 2 1 2 2 2 3 0 2 1 3 5 0 4 2 0 You may find the following diagram useful: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 C. True/False? (1) Longer passwords are more secure than shorter passwords. [True] (2) For public key encryption, an encryption key is actually made public rather than being kept a secret. [True] (3) In classical cryptography, such as the Caesar Cipher, the keys were widely known. [False] (4) Digital signatures should include timely info to thwart replay attacks. [True] (5) One time pads, properly used, produce code that is absolutely unbreakable. [True] (6) For classical encryption, the same key could be used again and again, while for public key encryption, the public key should only be used once (for good security). [False] D. I have a safe (or combination lock) which requires three numbers to open it. Each number can be one of 16 "digit values" (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F). A possible combination might be 7-E-4. How many different combinations are possible? (You do not need the exact numeric answer if you describe how it is calculated. For example you can specify 3^4 for 3 to the fourth power instead of calculating that this comes out to 81.) 16^3