NAME

paper-wallet - Script to generate a paper wallet file

SYNOPSIS

paper-wallet [OPTIONS]

OPTIONS

-a, --auto

Generate entropy automatically using cryptographically-secure pseudorandom number generator.

-o, --stdout

Do not print to file, use standard output instead. The script will not behave interactively and instead will wait for data on standard input without prompting anything. Best used with --auto and a single standard input line for password, or two lines: one for entropy, one for password

-f [FILE], --file [FILE]

Specify filename to print to - default is wallet.txt. Has no effect if --stdout is passed.

-w [NUMBER], --words [NUMBER]

A number of words to be generated. Must be 12, 15, 18, 21 or 24. Default 24.

-c [NUMBER], --compat_addrs [NUMBER]

A number of compat addresses to generate, by default 1.

-s [NUMBER], --segwit_addrs [NUMBER]

A number of segwit addresses to generate, by default 3.

-n [STRING], --network [STRING]

The identifier of the network for which to generate a wallet, by default 'bitcoin'. See Bitcoin::Crypto::Network for available networks. Note that not all networks support segregated witness addresses. If you specify a network which does not, the script will generate only non-segwit addresses.

-h, --help

Show this help message.

DESCRIPTION

This script will generate a file in your current working directory that contains Bitcoin wallet details ready to be printed, written down or stored on a flash drive. This file must not exist already or the script will fail (to ensure that you don't override your previously generated wallet that you might have already used).

This is intended to be used as cold storage (Bitcoin wallet which does not have active connection to the Internet). The generation should best take place while being offline.

The script will interactively ask for wallet password and entropy (random data that secures your funds). If you don't have any means to generate random data, like rolling dice, or you don't know how to properly do so (to ensure large enough entropy), it is recommended to use the --auto flag, which will use secure random generators to do it for you. Password can be skipped by hitting enter, but it is not recommended to do so. Remember that there is no way to restore your password, so make sure you won't lose it.

After printing, you can cut off the top section (mnemonic seed) and store it apart from the addresses for safety. You can also write the mnemonic seed down by hand and only print the addresses part.

Security

With Bitcoin, information is money. You should be wary (or even paranoid) of possible dangers during generation of your wallet.

If you want maximum safety, just buy a hardware wallet instead. Using a custom solution like this one requires you to have enough expertise to be a hardware wallet yourself. It can be a cool experience, but can also cost you money.

You should not depend on your passphrase and take securing your keys seriously. Keep your passphrase rather simple, as its only purpose is to buy you time in case of a leak. The danger of forgetting your passphrase is very real and with a long passphrase, it can be very hard to recover.

For increased security, follow these guidelines:

• Make sure your environment is as safe as possible

  Scan your machine for malware. Check if you have any suspicious processes running. Best, use security-focused system like OpenBSD.

• Disable Internet connection during generation

  If your seed is going to leak, it will do so through the Web. As long as you have the seed on your computer, avoid being online.

• Only store the seed physically

  Paper or metal are unhackable. If they are stolen, you can move the funds elsewhere before they crack your password - as long as you keep the second copy in a different location.

• Don't print the seed, write it down

  It is especially true if you have a printer which is connected to your local network. Regular USB-only printers should be fine, but you never know if they keep copies of what they printed somewhere. Never ever use printers you have at work.

• Remove the seed from your computer when you're done

Common pitfalls

Even if you safely generated the seed, you might still put it at risk without even knowing:

• If you opened a file with a program, it might have saved a draft copy somewhere

• Even if you deleted the file, it may still stick around in Trash

• Some systems may synchronize contents of a directory with the cloud

• If you forget your password, there's no way to recover it