| Date | May 2021 | Marks available | 2 | Reference code | 21M.3.HL.TZ0.1 |
| Level | HL | Paper | 3 | Time zone | no time zone |
| Command term | Identify | Question number | 1 | Adapted from | N/A |
Question
Refer to the Paper 3 Case study: a local economy driven by blockchain, available under the "Your tests" tab > supplemental materials.
Identify two characteristics of a digital signature.
Identify two stages in the proof-of-work process.
Markscheme
Award [2 Max]
Anonymity (signature key identifies the user but not their real name).
Asymmetric (cryptography);
Certificate authority stamp;
Collision resistant;
Data / transaction / message;
Deterministic;
Hash / bitstring;
Non-invertibility;
Non-repudiation;
Private key / Secret key
Public key / key generation;
Randomness (for Private key generation);
Secure / encryption;
Signature function / signing algorithm;
Timestamp (sometimes);
Unique.
Award [2 Max]
Candidate block is formed from transactions in the pool
Nonce is generated (based on difficulty level);
Miners try to find the nonce / Hash generated and compared to target / mathematical calculations / solving the problem;
Puzzle solved / Hash smaller than target;
Broadcast to distributed ledgers;
Other miners verify/validate;
Block added;
Reward is issued to successful miner;
