CS2020:   Web Science, Sytems and Design
   Asymmetric or Public-Key Encryption



The Idea:
  • A cryptographic system that uses two keys -- a public key known to everyone and a private or secret key known only to the recipient of the message.
  • When John wants to send a secure message to Jane, he uses Jane's public key to encrypt the message. Jane then uses her private key to decrypt it.
  • Known as PGP - Pretty Good Privacy system.
  • Public key cryptography was invented in 1976 by Whitfield Diffie and Martin Hellman.

Important:

 

    • only the public key can be used to encrypt messages and only the corresponding private key can be used to decrypt them.
    • it is virtually impossible to deduce the private key if you know the public key.

Problem:

 

    • Must know the recipient's public key to send them something encrypted.
    • Hence need some kind of public registry where people can register their public keys...otherwise they have to send it to you.

© Lynne Grewe