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# Four - Why is Yenta safe?

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Yenta has a lot of personal information, and it talks to other copies of itself all over the net. Why is this a safe thing to do?

Everything Yenta does is encrypted. Yenta encrypts all communications between Yentas, using SSL and full-strength, strong cryptography. It does the same between your Yenta and your browser. And, the data it saves to disk is similarly protected. Its RSA keys are 1024-bit. Its session keys are 128-bit. No compromises. No kidding.

Yenta's cryptography is well-tested. Home-made crypto is dangerous -- you never know if it's secure. So Yenta doesn't use any. Instead, it uses SSLeay for its cryptography -- the same package used in the cryptography-enhanced versions of Apache, the most popular web server on the net. It's also the same one used in open-source versions of Mozilla, the open-source version of Netscape's web browser. Large numbers of developers worldwide have examined this package carefully for flaws.

There's no central point to be compromised. Your data is your own. Unlike many other Internet-based services, there is no central point where everybody's data gets sent. This means you don't have to trust what somebody else says they'll do with your data. Since there's no central server, a cracker can't break it and learn everything about everyone. And since there's no one in charge, a lawyer can't show up with a subpoena and demand all the data. (Someone might still break your machine, or subpoena you, but they could do that whether or not you run Yenta. Besdies, all they'll be able to find out about is you, and you'll probably know about it. They can't undetectably find out about everybody -- and that protects you: unless you're the target, someone else's misfortune need not be yours. And finally, if you can't help them target someone else, they'll have less incentive to go after you, too.)

Yenta never discloses your name. When one Yenta sends a message to another, it uses a Yenta-ID -- a long random number -- to identify itself. If you want somebody else to know your real name or your real email address, you have to tell them yourself.

You cannot be impersonated. Your Yenta-ID is related to the private key that Yenta creates for you. This key is protected via a passphrase that you make up and remember. As long as you pick a good passphrase, and don't tell it to anyone, no other Yenta can impersonate yours -- because Yentas challenge each other cryptographically when they meet in a way that verifies the Yenta-ID without revealing the underlying private key.

You have plausible deniability. When your Yenta is exchanging interests with another, some of the interests it presents come from other Yentas. Your Yenta knows which ones -- but the other Yenta does not. So it has no way to be sure that any given interest even matches your Yenta-ID in the first place, unless you later tell it.

Yenta's source code is publicly available. You can't trust a black box. Yenta's source code is publicly available. Even better, we created a special tool called Yvette to allow large numbers of people to collaborate in reviewing Yenta's source code. Rather than having to trust the reputation of the developers, or read all the source code yourself, or hope you hear something in a newsgroup, you can read what others have said about individual pieces of the code. Of course, each review is cryptographically signed, so you can reliably figure out who said it, and be assured that it talks about exactly the code it claims to. And we encourage others to critique Yenta's security.

[ Important instructions and caveats next. See the next page. ]

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