Frequently Asked Questions For
Information Security Intelligence: Cryptographic Principles & Applications

This section of the website allows readers of the text Information Security Intelligence: Cryptographic Principles & Applications to ask the author questions. The author will post answers to the most commonly asked questions. If you have a question please send it to FAQ . The author also encourages readers to view the FAQ video lessons included on the CD-ROM portion of the book, where you will get a chance to view Professor Calabrese explain many of the more difficult topics in the text.

• What are viruses, worms and Trojan horses? Can you explain three ways that a virus might infect a computer system, or three ways that a worm can spread from machine to machine.
  
  
• It is common, for performance reasons, to sign a message digest of a message rather than the message itself. Why is it so important that it be difficult to find two messages with the same message digest?
  
  
• Assume a cryptographic algorithm in which performance for the good guys (the ones that know the key) grows linearly with the length of the key, and for which the only way to break it is a brute force attack of trying all possible keys. Suppose the performance for the good guys is adequate (e.g. it can encrypt and decrypt as fast as the bits can be transmitted over the wire) at a certain size key. Then suppose advances in computer technology make computers twice as fast. Given that both the good guys and the bad guys get faster computers, does this advance in computer speed work to the advantage of the good guys, the bad guys, or does it matter at all?
  
  
• Show that DES encryption and decryption are identical except for the order of the 48-bit keys.
  
  
• Describe the RSA Algorithm.
  
  
• Explain how to use (a) a shared secret and (b) public/private keys, to authenticate two communicating parties.

Many of the answers to FAQs are from lectures presented at JWU.