Cryptography

1. 1
   Easy levelThe SHA-256 Hashing Machine

   Hash a sentence, change one letter, and compare the fingerprints.

   Open the model I've tried it

   Optional challenge You change one letter of a sentence. What happens to its SHA-256 hash?

   One character of the hash changes About half of the 256 bits change Nothing, hashes ignore small changes Check answer

2. 2
   Advanced levelThe SHA-256 Hashing Machine

   Play the 64 rounds and switch on Bitcoin's double SHA-256.

   Open the model I've tried it

   Optional challenge A message is 56 bytes long. How many 512-bit blocks does SHA-256 process?

   One Two Seven Check answer

3. 3
   Explore levelThe Digital Signature Machine

   Sign a message, change it, and check it with another key.

   Open the model I've tried it

   Optional challenge A signature was made with Key A. You check it with Key B's public key. What does the verifier say?

   Valid, any key works Invalid: only Key A's public key matches It reveals Key A's private key Check answer

4. 4
   Explore levelThe Mining Machine

   See double SHA-256 at work: miners hash block headers until one meets the target.

   Open the model I've tried it

Finished? Choose another path or explore freely.