Clients: how to send APDUs

Clients can communicate with the emulated device using APDUs, as usual. Speculos embbeds a TCP server (listening on to forward APDUs to the target app.

ledgerctl (ledgerwallet)

ledgerwallet is a library to control Ledger devices, also available through the command ledgerctl (it can be installed thanks to pip):

pip3 install ledgerwallet

If the environment variables LEDGER_PROXY_ADDRESS and LEDGER_PROXY_PORT are set, the library tries to use the device emulated by Speculos. For instance, the following command-line sends the APDU e0 c4 00 00 00 (Bitcoin app APDU to get the version):

$ echo 'e0c4000000' | LEDGER_PROXY_ADDRESS= LEDGER_PROXY_PORT=9999 ledgerctl send -
13:37:35.096:apdu: > e0c4000000
13:37:35.099:apdu: < 1b3001030e0100039000

blue-loader-python (ledgerblue)

Most clients relies on the blue-loader-python Python library which supports Speculos since release 0.1.24. This library can be installed through pip using the following command-line:

pip3 install ledgerblue

The usage is similar to ledgerctl:

$ ./ ./apps/btc.elf &
$ echo 'e0c4000000' | LEDGER_PROXY_ADDRESS= LEDGER_PROXY_PORT=9999 python3 -m ledgerblue.runScript --apdu
=> b'e0c4000000'
<= b'1b30010308010003'9000
<= Clear bytearray(b'\x1b0\x01\x03\x08\x01\x00\x03')


Use btchip-python without a real device:


Note: btchip-python relies on its own library to communicate with devices (physical or emulated) instead of ledgerblue to transmit APDUs.


./tools/ &
DEBUG_COMM_HTTP_PROXY= ledger-live getAddress -c btc --path "m/49'/0'/0'/0/0" --derivationMode segwit