1. Remarks on Voting using Cryptography Ronald L. Rivest MIT Laboratory for Computer Science

2. Outline u Cryptography can do surprising things u Cryptography needs a secure platform

3. Cryptography can be surprising u Not only digital signatures: (created with private signing key, verifiable with public key, authenticates both signer and message) u But blind digital signatures: (signer doesn’t see what he is signing)

4. Cryptography can be surprising u Not only encryption: (provides confidentiality against eavesdroppers, ciphertext can only be decrypted with proper key) u But homomorphic encryption: (product of ciphertexts encrypts sum of plaintexts: E(3) x E(5) = E(8))

5. Cryptography in Theory Alice SK A Voting System

6. Cryptography in Practice SK A Alice! Voting System Alice? Crypto needs secure platform; modern OS’s are not very secure.

7. Can SK A go on a smart card? SK A Alice? Voting System Alice?

8. (THE END)