BAC-L3-XCHAIN-102Interoperable systems engineering
Light clients: what is actually verified
The mechanism that makes trust-minimised interoperability possible, and the cost that explains why so many bridges skip it.
- Level
- L3 — Infrastructure engineer
- Duration
- 4 h
- Maintainer
- Chief Blockchain Architect
Learning objectives
- 01Describe what a light client verifies and what it assumes
- 02Implement verification of a remote header
- 03Assess the on-chain cost of that verification
Guided lab
Implement a header verifier for a remote chain and measure its cost.
Independent lab
Compare verification cost across two distinct consensus protocols.
Security angle
A stale light client accepts an obsolete chain: freshness is part of the security.
Assessment
Working verifier with a documented cost measurement.