this post was submitted on 18 Oct 2023
9 points (84.6% liked)
Programming
17313 readers
261 users here now
Welcome to the main community in programming.dev! Feel free to post anything relating to programming here!
Cross posting is strongly encouraged in the instance. If you feel your post or another person's post makes sense in another community cross post into it.
Hope you enjoy the instance!
Rules
Rules
- Follow the programming.dev instance rules
- Keep content related to programming in some way
- If you're posting long videos try to add in some form of tldr for those who don't want to watch videos
Wormhole
Follow the wormhole through a path of communities [email protected]
founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
This is about PKI. An HTTPS server has a TLS cert, and that TLS cert is signed by / created by a certificate authority (or CA). When you connect to a service over HTTPS, a TLS handshake happens. The handshake starts by the client asking a server to setup a session, and the server hands back it's certificate. This certificate can be used to encrypt traffic, but not decrypt it. The client makes sure the certificate is signed by a CA it trusts (such as let's encrypt).
Once the client has this certificate, it sends a key to the server in encrypted form, and the server decrypts it. They both now use this key to communicate.
The MITM server can't compromise the session because: If it swaps the certificate (or in other words, the encryption key the server sent), that key won't be trusted because it isn't signed by a CA the client trusts.
If the MITM tries to send its own shared key signed by the servers certificate - it doesn't really matter since it can't read the clients messages anyways to get the shared key from the client. If it forwards it, then you effectively have two separate https sessions with their own keys, and the server will treat them as distinct.