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Online Cryptography Course Dan Boneh. Introduction. What is cryptography?. Crypto core. Talking to Alice. Talking to Bob. Secret key establishment: Secure communication:. Alice. Bob. a ttacker???. m 1. k. k. m 2. c onfidentiality and integrity.
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Online Cryptography Course Dan Boneh Introduction What is cryptography?
Crypto core Talking to Alice Talking to Bob Secret key establishment: Secure communication: Alice Bob attacker??? m1 k k m2 confidentiality and integrity
But crypto can do much more • Digital signatures • Anonymous communication Alice Alice signature Who did I just talk to? Bob
But crypto can do much more • Digital signatures • Anonymous communication • Anonymous digital cash • Can I spend a “digital coin” without anyone knowing who I am? • How to prevent double spending? Alice Who was that? 1$ Internet (anon. comm.)
Protocols • Elections • Private auctions
Protocols • Elections • Private auctions • Secure multi-party computation trustedauthority Goal: compute f(x1, x2, x3, x4) “Thm:” anything the can done with trusted auth. can also be done without
Crypto magic What did she search for? • Privately outsourcing computation • Zero knowledge (proof of knowledge) Alice Alice Bob searchquery E[ query ] E[ results ] results ??? I know the factors of N !! proof π N=p∙q N
A rigorous science The three steps in cryptography: • Precisely specify threat model • Propose a construction • Prove that breaking construction under threat mode will solve an underlying hard problem