CSE 451

Operating Systems

Spring 1998


Quiz #7

Distributed :  5/26/98 (Tuesday)
Due            :  5/28/98 (Thursday -- in the beginning of the Section)

The Hacker's Problem!

The TELNEX operating system uses paging for virtual memory. It gives application programs additional flexibility by allowing them to register a callout function which gets called whenever a page fault occurs. TELNEX also used passwords to protect files. To access a file, the application program had to present the proper password. This was done by passing a pointer to the password string to the open() system call for opening a file. The operating system checked passwords one character at a time, stopping as soon as it saw the password was wrong.

Come up with an efficient method to break this security system. That is given a file, come up with a method to systematically find the password associated with the file.

Assume that the passwords are exactly 8 characters long.