How does tor encrypt my data?

[F. Fox]

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孙超 wrote:
(snip)
> We know that there is an entrance node and an exit node in a path,
> cleartext is sent out from the exit node to the destination that we are
> aimed at. If so, my original cleartext could be revealed to the exit
> node? If my data is encrypted on my PC by the tor I runned, how does the
> exit node decrypt the ciphered text? How does it get the decrypt key?
> 

You should read the Tor FAQ; these questions are answered there:
https://wiki.torproject.org/noreply/TheOnionRouter/TorFAQ#head-75d5f6d474527a80fc370d208252b4dfd2ea2efd

I will answer the most important one in short here, though: Unless
you're using something that provides end-to-end encryption (HTTPS,
encrypting email with PGP/GPG, using SSH for logging into things, etc.),
exit nodes can - and have been known to - spy on cleartext. They can
also alter things being passed through; this is how Torment and similar
tools attempt to "demask" those who haven't properly secured their browser.

> Another question is what kind of cryptology algorithm tor uses, RSA? or
> others?

A bit about the public-key side of Tor:
https://wiki.torproject.org/noreply/TheOnionRouter/TorFAQ#head-808ed17a2519e7851b33bcc620b67b97cac76511

I do know that AES is used on the symmetric-key side (although I don't
know what key length is used).

- --
F. Fox: A+, Network+, Security+
Owner of Tor node "kitsune"
http://fenrisfox.livejournal.com
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