# HW4 - HW#4 Hash Functions Message Authentication Code Key...

This preview shows pages 1–2. Sign up to view the full content.

HW #4: Hash Functions, Message Authentication Code, Key Distribution and Protocols CS 392/6813: Computer Security Fall 2009 [100pts] DUE 11/03/2008 (midnight) Problem 1 [30pts] Assume that the IP address assignment is performed using the following function: IP: H Æ {0,1} 32 , which on input of a host h on the internet, outputs its IP address as a 32-bit long number uniformly distributed at random. At least how many hosts would we need to gather over the internet such that at least two have of them have the same IP address with a probability greater than 0.6? Show all steps involved. Does this represent a good way for IP address assignment? Why or why not? Problem 2 [10+5+5 = 20pts] (1) Bob downloaded a 30GB tar.gz file from Alice’s server today. Bob needs to know if he downloaded the correct file and that there were no errors in the transmission, before attempting to unzip/untar it (since uncompressing such a big file might take a long time and computational resources). Unfortunately, Alice and Bob do

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 2

HW4 - HW#4 Hash Functions Message Authentication Code Key...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online