gcnaccount / pywallet

Offline Multicoin Wallet Generation in Python

pywallet

Offline Multicoin Wallet Generation in Python

Implements offline wallet generation to support secure, manual, offline, and cold wallet generation. It supports multiple coin types, including Bitcoin (BTC), Bitcoin cash (BCH), and Litecoin (LTC). It conforms to the BIP 32, BIP 44, and BIP 39 standards for Hierarchical Deterministic (HD) wallets.

The software (btc.py / bch.py / ltc.py) outputs the wallet seed as a 24-word (264-bit) mnemonic which can be written on paper, stamped on to metal, or encoded in a fireproof device (e.g. a cryptosteel.com device or similar). The mnemonic phrases output by this tool may be imported into wallet software such as Electrum, Mycelium, and Coinomi or any wallet that conforms to BIP 44 address paths and supports importing BIP 39 menmonic phrases.

Note that the phrase output by any of the generation scripts (btc.py / bch.py / ltc.py) can be used to recover the same HD wallet seed using any of these three scripts.

The code is designed for maximum readability and simplicity rather than for optimal performance. This makes it easier to audit the code and ensure the absence of backdoors. There are no external library dependencies and relevant classes (in base.py) are together less than 500 lines of code. The most critical sections to review in any wallet generation software are the random seed generation and derivation of addresses. The corruption of either process could result in the loss or theft of coins.

Note that this software is not intended for production use. It should only be used as a secondary or tertiary generation method to compare against outputs made by other offline wallet generation tools, e.g., together with a downloaded copies of generation tools such as:

• https://iancoleman.github.io/bip39/ together with
• https://www.ledgerwallet.com/support/bip39-standalone.html together with
• https://coinomi.com/recovery-phrase-tool.html

Using this tool, with its easily audited code, helps establish confidence in the proper calculation of wallets and addresses, which helps to ensure that generation is performed both randomly and correctly.

Usage:

Execute internal tests:

$ python <btc.py/bch.py/ltc.py> test

This runs a suite of tests to ensure correct operation using published test vectors. This 
should be run at least once on the machine on which you intend to generate keys. The test 
script ("test-all.sh") performs additional tests. It verifies that the outputs of this tool 
can be used to recover the same seed and derive the same keys and addresses.

Generate new private key:

$ python <btc.py/bch.py/ltc.py> generate [additional entropy] [passphrase]

This generates a new random key and outputs a 24-word mnemonic phrase which may be used to 
recover the key at any future time. Additional entropy may be supplied as an additional string, 
such as the outcome of 256 coin tosses, or 100 die rolls. This should be done if the entropy 
source on the offline computer is suspect. An optional passphrase may be supplied but this must 
be remembered and re-entered along with the mnemonic to complete the recovery.

Recover a private key:

$ python <btc.py/bch.py/ltc.py> recover "mnemonic phrase" [passphrase]

This recovers a private key from the 24-word mnemonic and optionally a passphase (if one was 
supplied during generation). It is prudent to perform a recovery of any newly generated and 
backed up private key to ensure it is properly recorded *before* sending any coins to it.  
Additionally, verifying proper receipt and spendability with a low value of coins is good to 
ensure a correct correspondance between the displayed public address and the private key.