ledgercomm

LedgerCOMM

Overview

Python library to send and receive APDU through HID or TCP socket. It can be used with a Ledger Nano S/X or with the Speculos emulator.

Install

If you just want to communicate through TCP socket, there is no dependency

$ pip install ledgercomm

otherwise, hidapi must be installed as an extra dependency like this

$ pip install ledgercomm[hid]

Getting started

Library

from ledgercomm import Transport

# Nano S/X using HID interface
transport = Transport(interface="hid", debug=True)
# or Speculos through TCP socket
transport = Transport(interface="tcp", server="127.0.0.1", port=9999, debug=True)

#
# send/recv APDUs
#

# send method for structured APDUs
transport.send(cla=0xe0, ins=0x03, p1=0, p2=0, cdata=b"")  # send b"\xe0\x03\x00\x00\x00"
# or send_raw method for hexadecimal string
transport.send_raw("E003000000")  # send b"\xe0\x03\x00\x00\x00"
# or with bytes type
transport.send_raw(b"\xe0\x03\x00\x00\x00")

# Waiting for a response (blocking IO)
sw, response = transport.recv()  # type: int, bytes

#
# exchange APDUs (one time send/recv)
#

# exchange method for structured APDUs
sw, response = transport.exchange(cla=0xe0, ins=0x03, p1=0, p2=0, cdata=b"")  # send b"\xe0\x03\x00\x00\x00"
# or exchange_raw method for hexadecimal string
sw, reponse = transport.exchange_raw("E003000000")  # send b"\xe0\x03\x00\x00\x00"
# or with bytes type
sw, response = transport.exchange_raw(b"\xe0\x03\x00\x00\x00")

CLI

Usage

When installed, ledgercomm provides a CLI tool named ledgercomm-send

$ ledgercomm-send --help
usage: ledgercomm-send [-h] [--hid] [--server SERVER] [--port PORT] [--startswith STARTSWITH]
                       {file,stdin,log} ...

positional arguments:
  {file,stdin,log}      sub-command help
    file                send APDUs from file
    stdin               send APDUs from stdin
    log                 send APDUs from Ledger Live log file

optional arguments:
  -h, --help            show this help message and exit
  --hid                 Use HID instead of TCP client
  --server SERVER       IP server of the TCP client (default: 127.0.0.1)
  --port PORT           Port of the TCP client (default: 9999)
  --startswith STARTSWITH
                        Only send APDUs starting with STARTSWITH (default: None)

Example

If Speculos is launched with default parameters or your Nano S/X is plugged with correct udev rules, you can send APDUs from stdin

$ echo "E003000000" | ledgercomm-send stdin  # Speculos
$ echo "E003000000" | ledgercomm-send --hid stdin  # Nano S/X

Or you can replay APDUs using the following text file named apdus.txt with some condition

# this line won't be send if you've the right STARTSWITH condition
=> E003000000
# another APDU to send
=> E004000000

then

$ ledgercomm-send --startswith "=>" file apdus.txt