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Slides from CS 161

Goal: a secure end-to-end channel

  • End-to-end: client trusts server, with no need to trust any intermediate nodes
  • Threats: eavesdropping (solve with encryption), manipulation (solve with integrity), replay attacks, DoS attacks, impersonation (solve with signatures), forward secrecy


SSL and TLS are used interchangeably, but technically TLS is the correct term

  • SSL = Secure Sockets Layer (predecessor)
  • TLS = Transport Layer Security (current)

Caveat: TLS encrypts any TCP traffic, it sits on top of TCP. It's NOT only for HTTP

Can use either RSA or Diffie-Hellman

End-to-end = strong protections

  • Attacker sniffs our network traffic on the wire. No problem, it's encrypted!
  • Attacker poisions our DNS cache, giving us the wrong IP address for the website. No problem, cert validation fails!
  • Attacker injects new traffic into our connection. No problem, receiver rejects it to failed integrity check!