Create, print, scan and verify paperwallets for cold storage #3351

Having hundreds of badly developed and programmed Bitcoin applications does not help the cause of Bitcoin. So Bitcoin-QT should conservatively implement all important functions of Bitcoin usage.

I assume we all agree digital storage is not build for eternity. Bitcoin-QT should definitely support cold storage. I suggest to create Bitcoin addresses NOT storing the private keys in the wallet file or any other digital storage but printing them on paper using QR-codes and OCR-A font. Bitcoin-QT should also have functions to scan paperwallets, read their QR-codes, fall back to optical character recognition and verify the scanned private keys match the Bitcoin addresses.

This will prevent average-joes loosing their savings which would have a big negative impact on the reputaion of the Bitcoin system.

A more diverse ecosystem of client implementations is important for Bitcoin to be truly decentralised, although I agree the quality of all implementations falls short often. Armory seems to have good paper wallet support today, and hopefully Bitcoin-Qt will in the future.

This is a duplicate of #3212, which already deals with paper wallets.

And paper wallets have their own risks, they are not a panacea for people that don't know what they're doing.

For one, the computer printed from should be offline, so that the private keys have never touched the network. Bitcoin-qt, in contrast with Armory, is very much unsuited for offline usage.

We'll also need deterministic wallet support, otherwise the printed backup will be out of date as soon as it's printed.

Also: many printers these days are networked (allowing interception on the wire), or store printed pages (if only for a while).

The computer should be offline and run off some kind of non-writable data storage (e.g. CD/DVD). It's not necessary to re-print the backup when using specific Bitcoin addresses for cold storage which only receive but don't send Bitcoins.

Armory has solved the printer hacking/sniffing problem by printing encoded addresses/keys on the paper wallet. Afterwards the user has to write down the code on the paper wallet manually.

That's my point. It's much better to do this with armory, which is designed to be able to be used offline.

There is no use in running Bitcoin-Qt from a non-writable storage, as you need somewhere to store the block chain. Bitcoin-Qt is primarily a full P2P network node, and a wallet secondary.

Closing as duplicate