Add handling of QR Code PK as a 3rd row of the paper wallet output

[truedat101]

This is related to #2 , conceptually we were thinking to add PK as another output from the QR codes for the paper wallet. I tested and it does work as a QR code in the third row, however it does not work with JAXX. Maybe JAXX has other issues, as I see other people complaining about it's less than stellar import capabilities. Is this PK encrypted?

You are free to decide if this is a good addition or not. I will separately explore what other wallet, maybe an electrum based one, will be functional.

[matthiaszimmermann]

cool tx for your pull request :-) i would probably have done this in a similar way. question: according to [1] jaxx also provides manual private key entry that should bypass the qr code reader. does that work for you?

if not: jaxx might expect a hex encoded private key. if so, you could just adapt your getPrivateKey method to

public String getPrivateKey() {
	return Numeric.toHexStringWithPrefix(credentials.getEcKeyPair().getPrivateKey());
}

one more thought: it seems that the ethereum wallet is explicitly designed NOT to exhibit the private key in plain text [2]. so even if you get the jaxx import working (what i hope) i am not yet convinced that having the private key in its explicit form printed on the paper is actually a good idea. what are your thoughts on this?

[1] https://decentral.zendesk.com/hc/en-us/articles/217877418-How-do-I-transfer-funds-from-a-paper-wallet-private-key- [2] https://forum.ethereum.org/discussion/2330/wallet-file-to-private-key

[truedat101]

Certainly then, makes sense to remove the PK from the output. And I'll retry this suggestion per yours about hex encoding. Let me get a look at this stuff again. Thank you for the reference items.

[truedat101]

Ok, I've made a few updates taking into account your feedback. I still don't get JAXX importing to work. They don't specify the exact format, however, and it seems a number of people have this same issue. Feature doesn't work as advertised, and unfortunately JAXX is not OSS.