On: The World of Competitive Lockpicking

[Alupis]

That's a good idea.

Although, I'm inclined to say if you're giving your house key to someone you don't completely trust, you should maybe seek an alternate candidate.

Then again, "trust, but verify" is indeed a real thing. Your system provides the verification part.

[danielheath → Alupis]

Anyone thinking of going to this much effort: signatures are easily forged. Use glitter lipstick to seal the envelope and take a photo of the pattern - nobody will ever lay the same glitter pattern again.