Public Key Cryptography Demonstration

I'm planning a public key cryptography example for class tomorrow using a cardboard shoebox filled with a "treasure" (skittles) and using 2 combination padlocks to simulate public/private keys. My idea has been that the example of locking the box with the

1. receiver's public key, and then locking the box with the
   • assures confidentiality of the message - only the receiver's personal key can decrypt the message
2. sender's private key
   • similar to a digital signature, which provides sender authentication and non-repudiation of the message sent inside
3. sending the box to the receiver, who opens the sender's lock with the
4. sender's public key, and then opening the last lock with the
   • authenticates it came from the sender
5. receiver's private key
   • ensures confidentiality of the message

References:

• Public-key cryptography from Wikipedia is an exceptionally well written and documented explanation.
• How PGP Works from the Introduction to Cryptography. Excellent graphics depicting encryption/decryption and digital signatures.
• Transport Layer Security (the older name SSL for Secure Sockets Layer is more common)
• A Cryptographic Compendium contains the history of cryptography and some interesting diagrams of coding.

Additions - 2010

• RSA Demo Applet Richard Holowczak shows how the encryption / decryption works.
• Introduction to Public-Key Cryptography by Sun
• An Inexpensive Device for Teaching Public Key Encryption By Pendegraft, Norman in Journal of Information Systems Education
• Encryption demo device

Key terms

• Authentication is the process of verifying one's identity.
• Key exchange uses public key cryptography to share a session key.
• Confidentiality means protecting data from eavesdroppers.
• Non-repudiation and Digital Signatures. Public Key systems provide digital signatures that can not be repudiated or denied.

Return to Blog Notes - October 2009