Something you know

PINs/PUKs – phones, smartcards

  • What is the difference between a PIN and a PUK?
    CAPTCHA - Completely Automated Public Turing test to tell Computers and Humans Apart
    • A Turing test is…
    • A CAPTCHAis a challenge-response test used in computing to ensure that the response is generated by a person and not by other computers by requiring a user to type letters or numbers from a distorted image.
      • Positives
        • it distinguishes between a human and a machine, making things such as online polls more legitimate
        • reduce spam and viruses, making things such as online shopping safer
        • diminishes the abuse of free email account services that require users to enter what is shown in the CAPTCHA
    • Negatives
  • An awesome article about ways that humans are being “used” by playing games to help computers develop artificial intelligence. CAPTCHA is part of that


  • Positives:
    • Easiest and cheapest method for authenticating
    • Easy for users to change it periodically
  • Negatives:
    • Many people use the same one for multiple accounts
    • Peoples brains are not the best so we often write them down, keep them short, etc. which makes stealing or cracking them easier
    • These can be hacked
      • Brute force attack
      • If they are saved as plain text in a database on a server, if the database is hacked, the hacker has access to all of that information.
  • Because of the possibility of hacking, people should