IGC digital signature (G-record): was a flight really verified?

Anything you want to sell or use officially — an e-logbook, a licence application, a competition score — rests on the claim "this flight really happened this way." So how do you know an IGC file wasn't tampered with?

What is a G-record?

Certified loggers (FLARM, XCTrack, XC Tracer, LXNAV…) append a cryptographic signature (G-record) to the end of the flight file. If the file is edited afterwards, the signature structure breaks.

Four states

Variograph classifies every flight at upload time and stores the result:

• Signed — G-record present, file structure intact.
• Unsigned — no digital signature (most phone apps, GPX conversions).
• Invalid signature — a signature exists but the structure is broken: the file may have been modified after recording.
• Verified — cryptographically verified with the manufacturer's algorithm (a later stage).

Why at upload?

Because it can't be added retroactively. If you don't tag it today, in two years you're left with thousands of unverifiable flights and the whole archive can't carry a "verified" claim. Because Variograph keeps the raw file, past flights can be promoted retroactively as manufacturer validators are added.

Where it shows

A coloured signature badge appears on the advanced analysis top bar and in the My Flights list on your dashboard: Signed ✓, Unsigned –, Invalid Signature !. You can bulk-import your flights from settings → collection.

Is a signature enough?

No. A signature tells you the file wasn't modified, not that the data inside is good — for that you need the IGC data quality indicators. How we store your data is written up in the privacy policy.