Support for paper wallets

[thms]

Someone already asked about support for paper wallets in Multibit and Jim answered that Multibit doesn't support paper wallets because it doesn't have deterministic wallets yet but they are working on it;

Why is a deterministic wallet needed to create paper wallets? Isn't it just a matter of displaying private keys and address ready for print ?

[jim618]

Hi
The tricky bit in supporting paper wallets is that with MultiBit you don't have access to a 'block store' containing all the Bitcoin transactions.
The library we use, bitcoinj, supports SPV mode where you basically ask a node:

+ Give me all the transactions for the address 1ABC… from blockheight 200,000 to the present day.

MultiBit then stores those and keeps track of the balance.

With a paper wallet you don't know how old the address is.
Unfortunately the BIP38 encrypted address format does not include this 'private key creation date' either.

If you have an arbitary address and you don't know how old it is the only thing you can do is go back to the genesis block and query every block. This is very slow and inefficient. It probably takes an hour now to do this on WiFi.


You could produce a QR code of a private key and get the user to print it off yes, but then MultiBit wouldn't be (easily) able to import it and get the transactions. It seems a bit pointless to be only to do half the operation.