--- a/.hgignore	Sun Mar 14 01:22:37 2021 +0000
+++ b/.hgignore	Sun Mar 14 02:21:49 2021 +0000
@@ -3,4 +3,5 @@
 \.[oa]$
 
 ^pcsc/fc-pcsc-atr$
+^pcsc/fc-pcsc-backend$
 ^pcsc/fc-pcsc-list$

--- a/pcsc/Makefile	Sun Mar 14 01:22:37 2021 +0000
+++ b/pcsc/Makefile	Sun Mar 14 02:21:49 2021 +0000
@@ -1,12 +1,13 @@
 CC=	gcc
 CFLAGS=	-O2 -I/usr/include/PCSC
-PROGS=	fc-pcsc-atr fc-pcsc-list
+PROGS=	fc-pcsc-atr fc-pcsc-backend fc-pcsc-list
 
 INSTALL_PREFIX=	/opt/freecalypso
 
 INSTBIN=${INSTALL_PREFIX}/bin
 
 ATR_OBJS=	atrfunc.o atrmain.o connect.o context.o rdselect.o
+MAIN_OBJS=	atrfunc.o connect.o context.o main.o rdselect.o
 LIST_OBJS=	context.o rdlist.o
 
 all:	${PROGS}
@@ -14,6 +15,9 @@
 fc-pcsc-atr:	${ATR_OBJS}
 	${CC} ${CFLAGS} -o $@ ${ATR_OBJS} -lpcsclite
 
+fc-pcsc-backend:	${MAIN_OBJS}
+	${CC} ${CFLAGS} -o $@ ${MAIN_OBJS} -lpcsclite
+
 fc-pcsc-list:	${LIST_OBJS}
 	${CC} ${CFLAGS} -o $@ ${LIST_OBJS} -lpcsclite
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/pcsc/main.c	Sun Mar 14 02:21:49 2021 +0000
@@ -0,0 +1,109 @@
+#include <sys/types.h>
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <pcsclite.h>
+#include <winscard.h>
+
+extern SCARDCONTEXT hContext;
+extern SCARDHANDLE hCard;
+extern char *selected_reader;
+
+static
+decode_hex_digit(c)
+{
+	if (isdigit(c))
+		return c - '0';
+	else if (islower(c))
+		return c - 'a' + 10;
+	else
+		return c - 'A' + 10;
+}
+
+static
+parse_hex_input(inbuf, outbuf)
+	char *inbuf;
+	u_char *outbuf;
+{
+	char *cp;
+	unsigned count;
+
+	count = 0;
+	for (cp = inbuf; ; ) {
+		while (isspace(*cp))
+			cp++;
+		if (!*cp)
+			break;
+		if (!isxdigit(cp[0]) || !isxdigit(cp[1])) {
+			printf("error: invalid hex APDU input\n");
+			return(-1);
+		}
+		if (count >= 260) {
+			printf("error: command APDU is too long\n");
+			return(-1);
+		}
+		outbuf[count++] = (decode_hex_digit(cp[0]) << 4) |
+				  decode_hex_digit(cp[1]);
+		cp += 2;
+	}
+	return count;
+}
+
+static void
+apdu_exchange(cmd_apdu, cmd_apdu_len)
+	u_char *cmd_apdu;
+	unsigned cmd_apdu_len;
+{
+	LONG rv;
+	DWORD dwRecvLength;
+	u_char sim_resp_data[258];
+	unsigned n;
+
+	dwRecvLength = 258;
+	rv = SCardTransmit(hCard, SCARD_PCI_T0, cmd_apdu, cmd_apdu_len, NULL,
+			   sim_resp_data, &dwRecvLength);
+	if (rv != SCARD_S_SUCCESS) {
+		printf("SCardTransmit error: %s\n", pcsc_stringify_error(rv));
+		return;
+	}
+	if (dwRecvLength < 2) {
+		printf(
+		"error: SCardTransmit response is shorter than 2 SW bytes\n");
+		return;
+	}
+	for (n = 0; n < dwRecvLength; n++)
+		printf("%02X", sim_resp_data[n]);
+	putchar('\n');
+}
+
+main(argc, argv)
+	char **argv;
+{
+	char inbuf[576];
+	u_char cmd[260];
+	int rc;
+
+	parse_reader_select_opt(argc, argv);
+	setup_pcsc_context();
+	get_reader_list();
+	select_reader_by_num();
+	printf("R %s\n", selected_reader);
+	connect_to_card();
+	retrieve_atr("A");
+	putchar('\n');
+
+	while (fgets(inbuf, sizeof inbuf, stdin)) {
+		rc = parse_hex_input(inbuf, cmd);
+		if (rc < 0)
+			continue;
+		if (rc < 5) {
+			printf("error: command APDU is too short\n");
+			continue;
+		}
+		apdu_exchange(cmd, rc);
+	}
+
+	SCardDisconnect(hCard, SCARD_UNPOWER_CARD);
+	SCardReleaseContext(hContext);
+	exit(0);
+}