Security

Goals

Authentication
- A way to verify the sender is legitimate
- For authentication (of course)
Encryption
- How to hide the contents of the message
- For privacy
- Types
  - Keyless
    - Not secure
  - Symmetric
    - Both keys are the same
    - If there is a secure way to give the key to the other party and the other party is fully trusted
  - Asymmetric
    - Public key system
    - Computationally infeasible to derive one from the other
Obfuscation (aka Logic Locking)
- Obfuscate the design functionally and structurally
  - Achieved my modifying the state transition function
  - Normal behavior is enabled only upon application of a key
- Prevents
  - Reverse engineering
  - Hardware trojans (hiding malicious functionality inside larger chip design)
Watermarking
- For IP protection
- Does not hide anything
- Hiding something inside of the firmware which can prove that it’s yours in court
Physically Unclonable Function
- What you see is not what you get
- Process variations
  - No two transistors have the same parameters
  - Have to use special algorithms to adapt to the variations
- A silicon PUF can be used as an unclonable key
  - The lock has a database of challenge-response pairs
  - To open the lock, the key has to show that it knows the response to one or more challenges
  - So if you hack one chip, it only works with that one chip