Checkpoint
Network & Protocol
4 references
A fixed reference point in the chain used to reduce sync cost or defend against certain long-range attacks. Checkpoints can be hardcoded or socially coordinated.
Appears in 4 whitepaper sections
$SOL
Solana
Introduction
...d at that specific position in the chain by recomputing the hashes from a known checkpoint. Because SHA-256 is cheap to verify in parallel but expensive to generate seque...
Network Design
...mits a transaction, it includes a recent blockhash (a reference to a recent PoH checkpoint) that serves as a transaction lifetime marker. The transaction is valid only fo...
Proof of History
...cation (parallel, multi-core):
Core 1: hash_0 → ... → hash_999 ✓ matches checkpoint
Core 2: hash_1000 → ... → hash_1999 ✓ matches checkpoint
Core 3: hash_2000 ...
Proof of History Sequence
...hash_205) --
...
300 SHA256(hash_299) -- (checkpoint)
```
Multiple data items can be inserted at the same PoH index by hashing them...