Authentication: Symmetric Cipher Based

• Challenge response
  • Challenger sends a random number to the subject.
• Subject gives a response to the challenge
  • Response derived using cryptography. For example, the encryption of the challenge using a shared key.

Owner Integrity: PKI

• Digital Signature
  • Can only be generated using the private key.
  • Can be verified using the public key.
• Since private key is one person,
  • Only the owner can generate it.
  • A document may be hashed and the hash may be signed digitally by the owner of the private key.
• Any one can verify the sign. Must have access to the public key of the signer.

Authentication: PKI

• Challenge-Response
  • Challenger can ask the subject to sign a random number
  • Challenger has access to the “certified” public key of the subject.
• Only subject can sign it correctly since it must have the access to the private key.
• Challenger can verify using public key.