rust-cktap

A Rust implementation of the Coinkite Tap Protocol (cktap) for use with SATSCARD, TAPSIGNER, and SATSCHIP products.

This project provides PC/SC APDU message encoding and decoding, cvc authentication, certificate chain verification, and card response verification.

It is up to the crate user to send and receive the raw cktap APDU messages via NFC to the card by implementing the CkTransport trait. An example implementation is provided using the optional rust pcsc crate. Mobile users are expected to implement CkTransport using the iOS or Android provided libraries.

Supported Features

• IOS Applet Select
• CVC Authentication

Shared Commands

• status
• read (messages)
  • response verification
• derive (messages)
  • response verification
• certs
• new
• nfc
• sign (messages)
  • response verification
• wait

SATSCARD-Only Commands

• unseal
• dump

TAPSIGNER-Only Commands

• change
• xpub
• backup

Automated Testing with Emulator

1. Install and start cktap emulator
   • TapSigner: ./ecard.py emulate -t --no-init
   • SatsCard: ./ecard.py emulate -s
2. run tests: cargo test --features emulator

Manual Testing with real cards

Prerequisites

1. USB PCSC NFC card reader, for example:
   • OMNIKEY 5022 CL
2. Coinkite SATSCARD, TAPSIGNER, or SATSCHIP cards Install vendor PCSC driver
3. Connect NFC reader to desktop system
4. Place SATSCARD, TAPSIGNER, or SATSCHIP on reader

Run CLI

cargo run -p cktap-cli -- --help
cargo run -p cktap-cli -- certs
cargo run -p cktap-cli -- read