CS338 Computer Security
Friday, 22 April 2022

+ Questions about anything

+ New stuff on the course web page

+ TLS
- Names: SSL vs. TLS
    "Secure Sockets Layer" -- old version of this protocol (obsolete)
    "Transport Layer Security" -- new version (1.2 and 1.3 are OK to use)
- Names: what is "transport layer"?
    OSI Model of networking: layers
    Transport Layer: TCP, UDP (get a packet from one app to another across the net)
    Network Layer: IP (get a packet from one machine to another)

- Structure of a certificate: the heart of the matter


===== We'll pick up here on Monday =====

- Structure of a certificate
    - the details
    - using a browser to look
    - using the openssl command to look
    - converting between .cer (i.e. DER) and .pem
    - using the ASN.1 decoders to look
- Again: what does a certificate assert?
- How can Alice "validate" Bob's certificate
- How do we get our hands on the CA's public key?
- Other problems, so many problems
    - Delegation of trust from one CA to another
    - Expiration certificates
    - Revocation
...