CSE 127 Lecture 9: L9 10/25/18
26 Oct 2018
School
Department
Course
Professor
Document Summary
Asymmetric signature (commonly done against the hash of the signature) Rely that whoever generated the tag had the secret key. Cannot rely on tag not leaking info about the message! Cryptographic hash function - maps arbitrary length input to fixed-size string. Pre-image resistance - impractical to find input that generates specified output. Collusion resistance - impractical to find 2 inputs that hash to same output. Then any message alice encrypts will be encrypted using eve"s public key! Signing is a mechanical op that has no meaning in itself! Crypto promises: only someone who knows the private key can create a signature that verifies using the corresponding public key. Meaning of a digital signature is a matter of convention . Both signer and verifier should agree on meaning! Alice and bob need a way to get each other"s public key. Soalice and bob need a way to know that each has the real public key of the other!
