Keylight Crate Enables Offline License Validation in Rust Apps

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Keylight is a Rust crate that allows desktop and CLI applications to validate software licenses without an internet connection. It uses Ed25519-signed JSON documents called leases, which apps verify locally using a bundled public key — requiring no server call at startup. The system separates two distinct tasks: offline verification of license authenticity and periodic background revalidation to detect server-side changes like refunds or revocations. At launch, the app checks a cached lease instantly; network calls only occur when a scheduled revalidation is due. The synchronous crate uses blocking HTTP via ureq, requires no async runtime, and exposes a standalone verify_lease function for flexible use in custom gating logic or CLI tools.

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