Quote from: nc50lc on January 25, 2018, 07:52:20 AM

technically impossible.
The process of sweeping private keys involves a transaction in the blockchain.

I think what you meant was "importing" private keys.

But all in all, one time exposure of your paper wallet's private key means that you intended to spend its balance,
so there is no need for such security measure unless the wallet you're using is unsecured too.

No it is not impossible. The scanning and encryption of the private key is done offline, to protect it from the above mentioned dangers. Nobody can visually record or snoop your session, if this is done offline.

The App will have to contain some software to convert the QR Code to text and also a method to encrypt&decrypt the text, before it is validated on the Blockchain, when you go online again.

Quote from: hatshepsut93 on January 25, 2018, 08:36:29 AM

Quote from: nc50lc on January 25, 2018, 07:52:20 AM

technically impossible.
The process of sweeping private keys involves a transaction in the blockchain.

I think what you meant was "importing" private keys.

But all in all, one time exposure of your paper wallet's private key means that you intended to spend its balance,
so there is no need for such security measure unless the wallet you're using is unsecured too.

OP said that he wants to automatically sweep it as soon as he goes online, while having all the data encrypted, and I think the following program should work.

First, we need a digital camera to take a photo of QR code, then you connect it via USB to an offline machine, and decode the QR code from a photo to get the private key. Then you insert the address you want to sweep to, and the app creates a signed transaction with paper wallet's address as an input. Then you can transfer this signed transaction via USB or by scanning it's QR code on your phone, check that it is correct by some other software (Core, Electrum, etc.) and broadcast it.

But I'm not sure if this app is needed - it can be useful if someone is dealing with huge amounts of paper wallets, but if it's one-time only, then it's not a problem to do everything I've described step-by-step. Maybe it can be implemented as a feature in some wallet that already has a good cold storage functionality, like Electrum or Armory.

The App will reduce the risk in doing this ONLINE. You cannot have a situation where you stored coins securely for years in a paper wallet and the moment you go online to sweep it, then it is gone.

Every time I have to sweep paper wallets, I get that tightness in my ass, because you never know who is looking over your shoulder.

My long-term strategy for cold storage require me to have multiple paper wallets with small quantities. I do not want to store all my eggs in one paper wallet and every time I want to sell, I have to sweep all my coins and expose my whole hoard/private key. It just make sense to have multiple paper wallets, if you want to store bitcoins for a long time, but sometimes you have a need to use some and then you only have to sweep 1 or 2.