Lecture 11: April 22, 2026

Reading: text, §10.4.1–10.5, 11.1–11.2
Assignments: Homework 2, due April 28, 2026 (Note extension)

1. Greetings and felicitations!

2. Cryptographic Checksums
   1. Keyed vs. keyless

3. Digital Signatures
   1. Judge can confirm, to the limits of technology, that claimed signer did sign message
   2. RSA digital signatures: sign, then encipher, then sign

4. Session and interchange keys
   1. Normally public key cryptosystems used as key interchange system to exchange secret keys (cheap)
   2. Then use secret key system (too expensive to use public key cryptosystem for this)

5. Key Exchange
   1. Needham-Schroeder and Kerberos

Matt Bishop Office: 2209 Watershed Sciences Phone: +1 (530) 752-8060 Email: mabishop@ucdavis.edu

ECS 153A, Computer & Information Security & Privacy I Version of April 25, 2026 at 3:07PM

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