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Lampost Hash

  • One time password scheme
  • Server B authenticates A

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Enhanced Version

  • Uses Salting

Advantages

  • Two different accounts will have different hashes of the password
  • Retain the same password when n=1, just change the salt
  • Works against dictionary attacks

Disadvantages

  • n logins only
  • No mutual authentication
  • No shared secret for rest of the conversation

Small n Attack

The hacker can impersonate the server with n’ < n, effectively enabling to login from n’ → n. Counter → Sanity check

Human and Paper Environment

  • Code sheet with list of hashes, manual checking