CS100 Study Guide - Final Guide: Https, Public-Key Cryptography

• School: University of Waterloo
• Department: Computer Science
• Course: CS100
• Professor: Kevin Harrigan

Document Summary

Any device between your source of designation is able to read your package (i. e. evil postman : sender encrypt message, receiver decrypt message, evil postman unable to interpret message. How it works (+3 caesar cypher: shift every letter by 3 i. e. instead of a --> send d; instead of w --> send z, today we don"t use caesar cypher, we use really large numbers: Works as long as receiver and sender has the secret # to encrypt and decrypt. One-way function: given result, determine input, i. e. factoring. Modulo (remainders: 1337 10 = 133 + 7 remainder --> 1337 mod 10 = 7 or 1337 mod 100 = 37, given result, determine input, i. e. using remainder. Divide by 17 = 2: end result (of key exchange), sender and receiver end up with the same number; but entire world knows that 3x mod 17 is being sent + received.