Web-Based Secure Messaging System
Tom Kelliher, CS 325
100 points, due Feb. 26 and Mar. 12, 2010
You've just been hired by KeepingSecrets, Inc. to develop a free, Web-based
crypto system for the public (any number of users). The system will be
RSA-based and implemented using Perl CGI scripts. KS's CEO wants the
system to provide the following functions:
- Register a new user on the system, generating a private key/public
key pair for the new user, and storing the pair.
In addition to the key pair, the system stores username and password for
- Login and authenticate to the system as a returning user.
A user may only send or receive messages once they've logged-in and
- Securely send a message to another user on the system. The receiver
should have clear proof of the sender's identity.
- Securely retrieve a message sent by another user. Once a message has
been retrieved, it should be deleted immediately.
- You may work alone or in groups of size two. You must document
all assistance you receive from anyone other than me.
- You will find the CGI and Crypt::RSA Perl modules of great use.
Documentation is available on the Web at
search.cpan.org or on
phoenix using perldoc from a shell.
- Data may be stored in flat files or in a database (PostgreSQL). In
the latter case, you will want to have a look at the DBD::PG and DBI Perl
modules and have me create a database user on phoenix for you.
- You're going to need to determine how to do file or database I/O, as
well as learning to take advantage of the functional elements provided to
you within a Web form, pretty much on your own.
Each group will make a brief presentation on the 26th. This presentation
- The look and feel of the UI.
- How data will be stored and how it will be secured.
- An initial analysis of security risks from the following attack
Your security design should make use of principles we've discussed in
class, such as a layered defense.
You are to hand-in a written copy of your initial security analysis at
the beginning of class.
- The application at the UI level.
- The Internet at the TCP/IP level.
- A non-root user on the host system with only shell access.
- A non-root user on the host system with only CGI access.
- The root user.
- Each group will make another brief presentation on the 12th. This
presentation will address:
- Use of the system.
- Data storage within the system. (Be prepared to show actual, live
file or table data.)
- A final analysis of the security risks enumerated above.
- On the 12th, each team is to turn in hard-copy of all source code,
including any static HTML files, and a written analysis of security risks.
Source code must be documented to the extent that a person not familiar
with the code can quickly and easily become familiar with, and understand,
- Some of the things you should be pondering as you work on this
project are: finding good places in the system to hide backdoors that would
allow you to secretly alter data, triggering the backdoors without arousing
suspicion or affecting the overall integrity of the system's data, and
obscuring the backdoors from others who would be using the system or
studying your source code.
Thomas P. Kelliher