Day 3: Hashing and Integrity

Note: today’s Replit includes solutions for the previous two days required problems.

Lecture Topics

• notes
• hash functions
  • padding
  • the daisy-chain hash
  • formal definition: collision resistance
• MACs (message authentication codes)

Problems

Reminders:

• You can run tests for a function by running python main.py FUNCTION_NAME from the shell.

We’ll be working in the main.py file. The cryptoy.py library contains the PRG function, cryptoy.compression(seed, n_bytes) that you’ll use for the daisy-chain hash.

The required functions from previous days can also be imported and used.

• required:

  • pad_with_length
  • daisy_chain_hash
  • mac

• bonus:

  • merkle_root
  • write_merkle_proof