Hashes, Signatures and Certificates · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Fingerprints, seals, and chains of trust

Computing · Networks & Security · ages 21-22
Name ______________________   Date ____________

  1. What does a signature locked with a private key prove?

    • That the statement is true
    • Who produced the statement
    • That the site is safe

  2. What is a hash?

    • A short fingerprint of some data
    • A long backup of a server
    • A type of password manager

  3. Two different files can easily be crafted to share one fingerprint.

    Circle one:   True   False

  4. What claim does a certificate sign?

    • That a key belongs to a name
    • That a site has good design
    • That traffic is free

  5. Your recomputed fingerprint differs from the posted one. What do you know?

    • The file is definitely virus free
    • The file changed after the fingerprint was posted
    • The author changed their name

  6. What does the browser check at each chain link?

    • Page colors and fonts
    • Signature, requested name, and dates
    • The owner birthday

  7. A signed statement says the moon is cheese. What does the signature settle?

    • That cheese science is correct
    • Only who signed it, not whether it is true
    • That the moon changed shape

  8. The chain verifies up to a root on your computer. Who do you end up trusting?

    • The website alone with no help
    • Your own typing speed
    • The root keeper whose signature vouches down the chain
LightMySky · lightmysky.comW1-mt_qLHm767U87-s1

Answer key

For grown-ups. Fold this page away before handing over the rest.

Fingerprints, seals, and chains of trust W1-mt_qLHm767U87-s1

  1. Who produced the statement · Only the key holder could have locked it, which names the author.
  2. A short fingerprint of some data · A hash compresses data into a short fingerprint that changes with any edit.
  3. False · Crafting a match is impractical, which is why tampering shows.
  4. That a key belongs to a name · The signed statement binds a public key to a name like example dot com.
  5. The file changed after the fingerprint was posted · A mismatch means something altered the data after the fingerprint.
  6. Signature, requested name, and dates · Each link must verify, name the right site, and still be valid.
  7. Only who signed it, not whether it is true · Signatures prove authorship while saying nothing about truth.
  8. The root keeper whose signature vouches down the chain · Trust flows down the signatures from a root you already hold.
Worksheet · LightMySky