go-pcsc

Minimal, CGO-free PC/SC access for Go. Windows calls winscard.dll through golang.org/x/sys/windows; macOS loads the PCSC framework and Linux loads libpcsclite.so.1 at runtime through purego.

The package intentionally exposes only the primitives needed by token clients: reader enumeration, connect/disconnect, status/ATR and raw APDU exchange.

The opt-in hardware test expects a FIDO authenticator presented to a PC/SC reader:

PCSC_TEST_CTAPNFC=1 go test -run TestCTAPNFC -v

import "context"
import "github.com/go-ctap/pcsc"

ctx := context.Background()

for reader, err := range pcsc.Enumerate() {
	if err != nil {
		log.Fatal(err)
	}

	card, err := pcsc.Open(reader.Name)
	if err != nil {
		continue
	}
	defer card.Close()

	status, err := card.Status()
	if err != nil {
		log.Fatal(err)
	}
	log.Printf("reader=%q ATR=%x protocol=%d", status.Reader, status.ATR, status.Protocol)

	// SELECT the Token2 applet
	response, err := card.Transmit(ctx, []byte{0x00, 0xa4, 0x04, 0x00, 0x07, 0xa0, 0x00, 0x00, 0x05, 0x27, 0x21, 0x01})
	if err != nil {
		log.Fatal(err)
	}
	log.Printf("response=%x", response) // response includes SW1/SW2
}

Canceling an in-flight Transmit issues a best-effort SCardCancel for the card's PC/SC context and returns ctx.Err(). PC/SC implementations and reader drivers do not consistently guarantee that an in-flight APDU can be interrupted, so the native operation may continue after Transmit returns. The card remains serialized until that operation finishes. Do not automatically retry a canceled APDU: the card may already have processed it.