Secrecy and Symmetric Key Ciphers
Goals
- Gain high-level intuition for how PRPs are constructed
- Define basic security for encryption via the IND-CPA security game
- Prove basic criteria necessary for IND-CPA security
- Introduce encryption modes and analyze their security
Block Ciphers
- How are PRPs and block ciphers related?
- What are some examples of block ciphers?
- Should DES (or 3DES) be used today?
- At a high-level, how does AES work?
- What are some examples of way to attack block ciphers?
Semantic Security
- How is semantic security defined?
- Does IND-CPA imply security against plaintext recovery?
- Does IND-CPA imply security against key recovery?
- What are two simple tests that can tell you an encryption scheme is NOT IND-CPA secure?
Encryption Modes
- Why do we need modes?
- How does Electronic Code Book (ECB) encryption work?
- Is it secure?
- Why/why not?
- How does stateful counter mode work?
- Is it secure?
- Why/why not?
- How does randomized counter mode work?
- Is it secure?
- Why/why not?
- How does it compare to stateful counter mode?
- How does cipher block chaining (CBC) mode work?
- Is it secure?
- Why/why not?
- What are two common attacks on CBC mode?
- What is a padding oracle?