Public Key Architecture

• Invented by Diffie & Hellman in 1976
• Solves key exchange problem (mostly)
• Each user generates a key pair - public & secret (private) key
• Public key freely distributed (published on websites etc.)
• Private key protected by a passphrase
• Sending an encrypted message:
  • Encrypt message with recipient's public key
  • Message is only readable with recipient's secret key
  • If the message is intercepted it cannot be read