ChainProfiles.Mainnet.Checkpoints was an empty array with a "populate
before release" TODO, and even BlockHeaderInfo.MatchesCheckpoint()/
IsValidChild() — the methods meant to enforce it — were never called
anywhere in WalletSynchronizer. So on this LWMA chain, where PoW can't
be recomputed client-side (SkipPowValidation), a malicious or
eclipsing server could hand back any internally-consistent 80-byte
header for a Merkle proof: nothing tied it to the real Palladium
chain.
Populated Mainnet.Checkpoints with 24 real [height, hash, bits]
checkpoints (every 20,000 blocks + one near tip), pulled via RPC from
a fully-synced palladiumd. Testnet/Regtest are left empty (no node
available to verify against, and WalletSynchronizer already treats a
missing checkpoint as a no-op, so this is safe, just unanchored).
Added WalletSynchronizer.AnchorToCheckpointAsync: for every header
used in a Merkle proof, downloads the intervening headers back to the
nearest checkpoint at or below that height and verifies an unbroken
prev-hash chain terminating in the checkpoint's exact hash, finally
wiring up the previously-dead MatchesCheckpoint/IsValidChild. Verified
ranges are memoized in-memory per sync session to avoid re-walking.
Updated SECURITY.md and USERGUIDE.md to describe what is actually
enforced now (previously the guide deliberately avoided promising
checkpoint anchoring, since the array was empty).
davide
e349a80ddc