On Tue, Apr 14, 2020 at 9:13 AM Eli Vakrat eli@vakrat.com wrote:
Hello to the TOR dev team!
My name is Eli, I'm a high school student from Israel and I'm currently trying to implement a TOR Client in Python. Currently, my project is configured so that the python client (OP) has its guard node set as my local machine (which is running a downloaded version of TOR). I do this for debugging purposes so that if I send a malformed cell as the implemented client, I can read the debug log that the OR generates and see what I did wrong.
As I am writing this, I have successfully been able to make a v3 "in protocol" handshake by sending the proper VERSIONS and NETINFO cells that the OR has accepted.
Right now, I am working on getting the CREATE cell to work (with the TAP handshake), and when I send the cell to the OR It sends a DESTROY cell with the following message in the debug log:
Apr 14 12:24:51.166 [warn] Received create cell with unexpected circ_id 1. Closing.
To my understanding, the problem here is that the circuit id I have chosen is not valid.
I read from the tor spec that there is a range of acceptable circuit id's for each relay and it can be found in the long term 1024 bit RSA "signing key".
My question to you all is, how can I extract that range for the circuit ID's (along with any other relevant information) from the signing key? In other words, what is the "signing key" made up of, and how can I get the information that its made of?
The bottom line is I need to find out what valid circuit ID's I can send to OR's.
I am having a lot of fun doing this project so far and I hope to hear back from anyone who has an answer :)
Hi! This looks like a cool project.
So, it was only the earlier versions of Tor that chose circuit IDs based on RSA keys. In link protocol version 4 or higher (as negotiated by the VERSIONS cell), you can use any circuit ID that starts with a 1 bit:
"In link protocol version 4 or higher, whichever node initiated the connection sets its MSB to 1, and whichever node didn't initiate the connection sets its MSB to 0."
Hoping this helps,