From 7113263a00d8c9b09f0dfdb9590bfe2bab1bc776 Mon Sep 17 00:00:00 2001
From: Werner Koch <wk@gnupg.org>
Date: Thu, 26 Nov 2020 12:36:44 +0100
Subject: [PATCH] agent: Fix YK s/n and prettify the request card prompt for
 Yubikeys

* agent/divert-scd.c (ask_for_card): Detect and re-format the Yubikey
prompt.
* scd/app.c (app_munge_serialno): Fix Yubikey s/n munging.
(card_get_dispserialno): Ditto.
* scd/app-openpgp.c (get_disp_serialno): Remove.
(get_prompt_info): Use app_get_dispserialno.--
--
---
 agent/divert-scd.c | 23 +++++++++++++++++++----
 scd/app-openpgp.c  | 26 +-------------------------
 scd/app.c          | 28 +++++++++++++++++++---------
 3 files changed, 39 insertions(+), 38 deletions(-)

diff --git a/agent/divert-scd.c b/agent/divert-scd.c
index 7587d4478..273f3a869 100644
--- a/agent/divert-scd.c
+++ b/agent/divert-scd.c
@@ -59,10 +59,25 @@ ask_for_card (ctrl_t ctrl, const unsigned char *shadow_info,
   if (len == 32 && !strncmp (want_sn, "D27600012401", 12))
     {
       /* This is an OpenPGP card - reformat  */
-      memmove (want_sn, want_sn+16, 4);
-      want_sn[4] = ' ';
-      memmove (want_sn+5, want_sn+20, 8);
-      want_sn[13] = 0;
+      if (!strncmp (want_sn+16, "0006", 4))
+        {
+          /* This is a Yubikey.  Print the s/n as it would be printed
+           * on Yubikey 5. Example: D2760001240100000006120808620000
+           *                                        mmmm^^^^^^^^      */
+          unsigned long sn;
+
+          sn  = atoi_4 (want_sn+20) * 10000;
+          sn += atoi_4 (want_sn+24);
+          snprintf (want_sn, 32, "%lu %03lu %03lu",
+                    (sn/1000000ul), (sn/1000ul % 1000ul), (sn % 1000ul));
+        }
+      else  /* Default is the Zeitcontrol card print format.  */
+        {
+          memmove (want_sn, want_sn+16, 4);
+          want_sn[4] = ' ';
+          memmove (want_sn+5, want_sn+20, 8);
+          want_sn[13] = 0;
+        }
     }
   else if (len == 20 && want_sn[19] == '0')
     {
diff --git a/scd/app-openpgp.c b/scd/app-openpgp.c
index 36301ee8d..a30a8e8b5 100644
--- a/scd/app-openpgp.c
+++ b/scd/app-openpgp.c
@@ -1381,30 +1381,6 @@ get_disp_name (app_t app)
 }
 
 
-/* Return the pretty formatted serialnumber.  On error NULL is
- * returned.  */
-static char *
-get_disp_serialno (app_t app)
-{
-  char *serial = app_get_serialno (app);
-
-  /* For our OpenPGP cards we do not want to show the entire serial
-   * number but a nicely reformatted actual serial number.  */
-  if (serial && strlen (serial) > 16+12)
-    {
-      memmove (serial, serial+16, 4);
-      serial[4] = ' ';
-      /* memmove (serial+5, serial+20, 4); */
-      /* serial[9] = ' '; */
-      /* memmove (serial+10, serial+24, 4); */
-      /* serial[14] = 0; */
-      memmove (serial+5, serial+20, 8);
-      serial[13] = 0;
-    }
-  return serial;
-}
-
-
 /* Return the number of remaining tries for the standard or the admin
  * pw.  Returns -1 on card error.  */
 static int
@@ -2324,7 +2300,7 @@ get_prompt_info (app_t app, int chvno, unsigned long sigcount, int remaining)
 {
   char *serial, *disp_name, *rembuf, *tmpbuf, *result;
 
-  serial = get_disp_serialno (app);
+  serial = app_get_dispserialno (app, 0);
   if (!serial)
     return NULL;
 
diff --git a/scd/app.c b/scd/app.c
index 933ad46d6..8a809e888 100644
--- a/scd/app.c
+++ b/scd/app.c
@@ -1208,10 +1208,22 @@ app_munge_serialno (card_t card)
           buf[7] = 0; /* thus we use 0.0 and don't use this directly.  */
           buf[8] = 0; /* Manufacturer: Yubico (0x0006).  */
           buf[9] = 6;
-          buf[10] = (sn >> 24);
-          buf[11] = (sn >> 16);
-          buf[12] = (sn >>  8);
-          buf[13] = sn;
+          buf[13] = (sn % 10);
+          sn /= 10;
+          buf[13] |= (sn % 10) << 4;
+          sn /= 10;
+          buf[12] = (sn % 10);
+          sn /= 10;
+          buf[12] |= (sn % 10) << 4;
+          sn /= 10;
+          buf[11] = (sn % 10);
+          sn /= 10;
+          buf[11] |= (sn % 10) << 4;
+          sn /= 10;
+          buf[10] = (sn % 10);
+          sn /= 10;
+          buf[10] |= (sn % 10) << 4;
+          sn /= 10;
           buf[14] = 0; /* Last two bytes are RFU.  */
           buf[15] = 0;
           xfree (card->serialno);
@@ -1311,15 +1323,13 @@ card_get_dispserialno (card_t card, int nofallback)
   else if (card && card->cardtype == CARDTYPE_YUBIKEY)
     {
       /* Get back the printed Yubikey number from the OpenPGP AID
-       * Example: D2760001240100000006008A77C10000
+       * Example: D2760001240100000006120808620000
        */
       result = card_get_serialno (card);
       if (result && strlen (result) >= 28 && !strncmp (result+16, "0006", 4))
         {
-          sn  = xtoi_2 (result+20) * 16777216;
-          sn += xtoi_2 (result+22) * 65536;
-          sn += xtoi_2 (result+24) * 256;
-          sn += xtoi_2 (result+26);
+          sn  = atoi_4 (result+20) * 10000;
+          sn += atoi_4 (result+24);
           if ((card->cardversion >> 16) >= 5)
             p = xtryasprintf ("%lu %03lu %03lu",
                               (sn/1000000ul),