Certified Variables

Query calls on the Internet Computer are fast because they skip consensus, but that means a malicious replica could lie to you. This skill shows you how to build cryptographically verified responses using Merkle trees and subnet BLS signatures. You hash your data structure, certify the root during updates, then attach certificates and witnesses to query responses so clients can verify authenticity against the IC root key. The examples cover both Rust (ic-certified-map, RbTree) and Motoko (CertifiedData module), plus the critical gotchas like forgetting to re-certify after upgrades or not checking certificate timestamps on the client. Use this when you need tamper-proof query responses without sacrificing speed.

Install to Claude Code

npx -y skills add dfinity/icskills --skill certified-variables --agent claude-code