Alex, I think the problem of making paper bitcoins is equivalent to the idea of creating paper implementation of bitcoin sidechain. Hard one in my mind. If we could resolve this one in secure and decentralized way it would be the same breakthrough as bitcoin itself is. Martin Sip On 18/05/2014 08:47 a.m., Alex Kotenko wrote: One problem we couldn't figure out here though - how to protect the notes from unauthorized redeem. Like if someone else tries to reach your wallet with his own NFC - how can we distinguish between deliberate redeem by owner and fraudulent redeem by anybody else with custom built long range NFC antenna? Any ideas? The firmcoin has two capacitive buttons that you have to press in sequence to redeem to coins. No long range antenna can do that. Best regards, Sergio. PS: the device has patents pending