fix ATR for windows usbccid.sys compat: correct length of historical bytes, and send TA1==0x13

2 files changed, 7 insertions, 1 deletions

diff --git a/vcard_emul_nss.c b/vcard_emul_nss.c
index 21da5f2..906f97b 100644
--- a/vcard_emul_nss.c
+++ b/vcard_emul_nss.c
@@ -354,6 +354,9 @@ vcard_emul_get_atr(VCard *card, unsigned char *atr, int *atr_len)
     ASSERT(atr != NULL);
 
     memcpy(atr, nss_atr, len);
+    // set the hb_length correctly (length of historical bytes), second byte, T1
+    // last nibble. Windows usbccid.sys needs this to be correct.
+    atr[1] = (atr[1] & 0xf0) + sizeof(nss_atr) - VCARD_ATR_MAIN_LENGTH;
     *atr_len = len;
     return;
 }
diff --git a/vcardt.h b/vcardt.h
index 44f41f8..885f2d1 100644
--- a/vcardt.h
+++ b/vcardt.h
@@ -28,7 +28,10 @@ typedef struct VCardEmulStruct VCardEmul;
 #define MAX_CHANNEL 4
 
 /* create an ATR with appropriate historical bytes */
-#define VCARD_ATR_PREFIX 0x3b, 0x6f, 0x00, 0xff, 'V', 'C', 'A', 'R', 'D', '_'
+#define VCARD_ATR_PREFIX 0x3b, 0x7f, 0x13, 0x00, 0xff, 'V', 'C', 'A', 'R', 'D', '_'
+
+/* length of non historical bytes part */
+#define VCARD_ATR_MAIN_LENGTH 5
 
 typedef enum {
     VCARD_DONE,