Key Concepts

• Modern cryptography provides a variety of mathematical tools for protecting privacy and security that extend far beyond the ancient art of encrypting messages.
• You can keep eaves­droppers from knowing what you are saying or to whom you are saying it.
• You can remain anonymous even in online activities that require you to sign in and prove facts about yourself.
• Groups can compute virtually anything from their members’ collective data (such as the winner of an election in which they are voting) without revealing any individual data.

Zack has decided to try out the online dating service Chix-n-Studz.com. He signs up for an account at the Web site and fills in several screens of forms detailing his personal profile and what he is looking for in a potential partner. In no time at all, the service offers him a number of possible soul mates, among them the very exciting-sounding Wendy. He sends her his e-mail address and what he hopes is an engaging opening message. She replies directly to him, and a whirlwind e-romance begins.

Poor Zack. Soon he is also getting numerous unsolicited phone calls from political action groups and salespeople who seem to know things about him, and his health insurance company is questioning him about his extreme-adventure vacations; the unscrupulous owners of Chix-n-Studz have been selling client information. Then there is Ivan, a mischievous co-worker to whom Zack foolishly showed one of Wendy’s e-mails. Zack does not know that several subsequent recent messages supposedly from Wendy are fakes from Ivan.

   
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