You're not the firt and not the last to search for a final year project:
Idea for Senior Project[
^]
See that link for just a few ideas.
To me it looks like there is a lot of image processing going on -> LAME!
Your idea about security is much better, how about using the current discussion about security on the web and do something in that area?
safe communication
user identification on emails
- how can I verify the email was send by the person it seems to be send by?
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