README.md

Last Word Checksum and XFP Calculator

THIS REPOSITORY COMES WITH ZERO GUARANTEES. USE AT YOUR OWN RISK!

Instructions:

1. Open Electrum Console tab
2. Enter the following (replace with your seed's first words):

first_words = "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon"

3. Paste the code from oneline.py into the console (it will use whatever you set first_words to in the previous step).
4. Private results (last word checksum) will be printed to the screen
5. Public results (extended public key, root fingerprint, and derivation path) are printed to the screen and saved to a file (for export to your multisig setup) in your /tmp directory

Note: it is strongly recommended to perform all these steps (including below) offline on an airgapped machine, preferably using Tails.

Example

Using the following INSECURE first_words:
first_words = "zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo"

Which generates the following output:

***************************************************************************************************
Running on network BitcoinMainnet...

PRIVATE SECRET TO WRITE DOWN (24 words total):

  zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo zoo buddy

PUBLIC KEY INFO TO LOAD INTO SPECTER-DESKTOP (also saved to /tmp/humanrngxp-669DCE62.json):

  [669DCE62/48'/0'/0'/2']Zpub74sb5KB3Ak1RwabGr8SHQnMTkd2mC3boVDgPf1jBFNxcXh7Nx4KV3XakPDtWLN5RpszdM7qcBN4wm7xreh8Ys2xYUBqQ9GtkTN8h5kRVecc

You can confirm this matches SeedPicker:
http://seedpicker.net/calculator/last-word.html

In order to run in testnet, you must boot electrum in testnet mode.

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Build Steps For Trust Minimization

Yes, this is sketchy! Electrum console has poor copy-paste support. We need our whole code in one-line.

Copy Code to Clipboard

Take the code from this repo (see electrum.py) and load it into your clipboard.

On MacOS, you can run:

$ cat electrum.py | pbcopy

Convert to One-Line

Convert code in your clipboard to one-liner on this website: https://jagt.github.io/python-single-line-convert/

Select Python 3 radio button, paste your code, and hit Convert.

Save the Resulting File

This is how oneline.py was created.

On MacOS, you can run:

$ pbpaste > oneline.py

Now you can use the steps at the top to calculate your last word checksum and root fingerpint.