Python library and command line tool for communicating with your Coldcard over USB
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README.md

Coldcard CLI and Python Interface Library

Coldcard is a Cheap, Ultra-secure & Opensource Hardware Wallet for #Bitcoin and other crypto-currencies.

Get yours at ColdcardWallet.com

This is the python code and command-line utilities you need to communciate with it over USB.

Setup For Everyday Use

  • pip install 'ckcc-protocol[cli]'

This installs a single helpful command line program: ckcc

If you just want the python library, use:

  • pip install ckcc-protocol

Setup If You Might Change the Code

  • do a git checkout
  • probable make a fresh virtual env
  • run:
pip install -r requirements.txt
pip install --editable '.[cli]'

Requirements

  • python 3.5.0 or higher
  • hidapi for USB HID access in a portable way.
  • see requirements.txt file for more details.

CLI Examples

Command Arguments

% ckcc
Usage: ckcc [OPTIONS] COMMAND [ARGS]...

Options:
  -s, --serial HEX  Operate on specific unit (default: first found)
  -x, --simulator   Connect to the simulator via Unix socket
  --help            Show this message and exit.

Commands:
  backup   Prompts user to remember a massive pass...
  debug    Start interactive (local) debug session
  list     List all attached Coldcard devices.
  logout   Securely logout of device (will require...
  msg      Sign a short text message
  reboot   Reboot coldcard, force relogin and start over
  sign     Approve a spending transaction (by signing it...
  test     Test USB connection (debug/dev)
  upgrade  Send firmware file (.dfu) and trigger upgrade...
  upload   Send file to Coldcard (PSBT transaction or...
  version  Get the version of the firmware installed
  xpub     Get the XPUB for this wallet (master level,...

Message Signing

% ckcc msg --help
Usage: ckcc msg [OPTIONS] MESSAGE

  Sign a short text message

Options:
  -p, --path TEXT  Derivation for key to use
  -v, --verbose    Include fancy ascii armour
  -j, --just-sig   Just the signature itself, nothing more
  --help           Show this message and exit.

% ckcc msg "Hello Coldcard" -p m/34/23/33
Waiting for OK on the Coldcard...
Hello Coldcard                    
1KSXaNHh3G4sfTMsp9q8CmACeqsJn46drd
H4mTuwMUdnu3MyMA+6aJ3hiAF4L0WBDZFseTEno511hNN8/THIeM4GW4SnrcJJhS3WxMZEWFdEIZDSP+H5aIcao=

Transaction Signing

% ckcc sign --help
Usage: ckcc sign [OPTIONS] PSBT_IN PSBT_OUT

  Approve a spending transaction (by signing it on Coldcard)

Options:
  -v, --verbose   Show more details
  -f, --finalize  Show final signed transaction, ready for transmission
  --help          Show this message and exit.

% (... acquire PSBT file for what you want to do ...)

% ckcc sign example.psbt out.psbt
5071 bytes (start @ 0) to send from 'example.psbt'
Uploading  [####################################]  100%
Waiting for OK on the Coldcard...
Ok! Downloading result (5119 bytes)

%  hd out.psbt | head -3
00000000  70 73 62 74 ff 01 00 fd  22 04 02 00 00 00 04 3f  |psbt...."......?|
00000010  ee 16 30 9d 14 82 36 dd  c8 3e 9e 4f 94 47 83 00  |..0...6..>.O.G..|
00000020  c2 23 e1 06 22 1b 02 0e  bd c8 1c 71 79 7d 3c 02  |.#.."......qy}<.|
00000030  00 00 00 00 fe ff ff ff  4c 85 a0 2c 80 cb 2c 01  |........L..,..,.|