Capture SSL premaster key - Python Youtube-DL

Question

I have a script in Python that is simply download some video with youtube-dl library. Please note: script is running in Anaconda Environment. On top of it I have a tshark capture all network traffic. I'm looking for a way to capture and decode the SSL Pre Master key. Is it possible to capture and save it in order to be re-used to decrypt traffic with WhireShark?

I'm using (in Anaconda env): Python 3.6.5 - OpenSSL 1.1.1c 28 May 2019

Answer 1

In order to capture SSL keys, you need to set the $SSLKEYLOGFILE environmental variable. I wrote an article on using Firefox to download a website's HTML and then decrypting it. Other people have also written good articles on doing this:

• SSL Decryption Guide: How to Decrypt SSL with Wireshark: Covers all 3 major Operating Systems
• Using Wireshark to Decode SSL/TLS Packets: SSL decryption discussion by Packet Pushers

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For youtube-dl to take advantage of the $SSLKEYLOGFILE variable, you need Python 3.8 and OpenSSL 1.1.1.