From b284412786d71c1cf382e1dff3a36ec6cce11556 Mon Sep 17 00:00:00 2001
From: Werner Koch <wk@gnupg.org>
Date: Wed, 16 Nov 2022 17:15:36 +0100
Subject: [PATCH] gpg: Add a notation to encryption subkeys in de-vs mode.

* g10/keygen.c (struct opaque_data_usage_and_pk): Add cpl_notation.
(do_add_notation): New.
(keygen_add_key_flags_and_expire): Set cpl@gnupg.org notation if
requested.
(write_keybinding): Request notation for subkeys in de-vs mode.
--

GnuPG-bug-id: 6279
---
 g10/keygen.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 57 insertions(+), 3 deletions(-)

diff --git a/g10/keygen.c b/g10/keygen.c
index d0731182c..e1fc8d6d0 100644
--- a/g10/keygen.c
+++ b/g10/keygen.c
@@ -121,9 +121,11 @@ struct output_control_s
 };
 
 
-struct opaque_data_usage_and_pk {
-    unsigned int usage;
-    PKT_public_key *pk;
+struct opaque_data_usage_and_pk
+{
+  unsigned int usage;
+  const char *cpl_notation;
+  PKT_public_key *pk;
 };
 
 
@@ -153,6 +155,9 @@ static gpg_error_t gen_card_key (int keyno, int algo, int is_primary,
                                  u32 expireval);
 static unsigned int get_keysize_range (int algo,
                                        unsigned int *min, unsigned int *max);
+static void do_add_notation (PKT_signature *sig,
+                             const char *name, const char *value,
+                             int critical);
 
 
 
@@ -303,12 +308,16 @@ keygen_add_key_flags (PKT_signature *sig, void *opaque)
 }
 
 
+/* This is only used to write the key binding signature.  It is not
+ * used for the primary key.  */
 static int
 keygen_add_key_flags_and_expire (PKT_signature *sig, void *opaque)
 {
   struct opaque_data_usage_and_pk *oduap = opaque;
 
   do_add_key_flags (sig, oduap->usage);
+  if (oduap->cpl_notation)
+    do_add_notation (sig, "cpl@gnupg.org", oduap->cpl_notation, 0);
   return keygen_add_key_expire (sig, oduap->pk);
 }
 
@@ -860,6 +869,44 @@ keygen_add_keyserver_url(PKT_signature *sig, void *opaque)
   return 0;
 }
 
+
+/* This function is used to add a notations to a signature.  In
+ * general the caller should have cleared exiting notations before
+ * adding new ones.  For example by calling:
+ *
+ *  delete_sig_subpkt(sig->hashed,SIGSUBPKT_NOTATION);
+ *  delete_sig_subpkt(sig->unhashed,SIGSUBPKT_NOTATION);
+ *
+ * Only human readable notaions may be added.  NAME and value are
+ * expected to be UTF-* strings.
+ */
+static void
+do_add_notation (PKT_signature *sig, const char *name, const char *value,
+                 int critical)
+{
+  unsigned char *buf;
+  unsigned int n1,n2;
+
+  n1 = strlen (name);
+  n2 = strlen (value);
+
+  buf = xmalloc (8 + n1 + n2);
+
+  buf[0] = 0x80; /* human readable.  */
+  buf[1] = buf[2] = buf[3] = 0;
+  buf[4] = n1 >> 8;
+  buf[5] = n1;
+  buf[6] = n2 >> 8;
+  buf[7] = n2;
+  memcpy (buf+8, name, n1);
+  memcpy (buf+8+n1, value, n2);
+  build_sig_subpkt (sig,
+                    (SIGSUBPKT_NOTATION|(critical?SIGSUBPKT_FLAG_CRITICAL:0)),
+                    buf, 8+n1+n2 );
+  xfree (buf);
+}
+
+
 int
 keygen_add_notations(PKT_signature *sig,void *opaque)
 {
@@ -909,6 +956,7 @@ keygen_add_notations(PKT_signature *sig,void *opaque)
   return 0;
 }
 
+
 int
 keygen_add_revkey (PKT_signature *sig, void *opaque)
 {
@@ -1167,6 +1215,12 @@ write_keybinding (ctrl_t ctrl, kbnode_t root,
 
   /* Make the signature.  */
   oduap.usage = use;
+  if ((use & PUBKEY_USAGE_ENC)
+      && opt.compliance == CO_DE_VS
+      && gnupg_rng_is_compliant (CO_DE_VS))
+    oduap.cpl_notation = "de-vs";
+  else
+    oduap.cpl_notation = NULL;
   oduap.pk = sub_pk;
   err = make_keysig_packet (ctrl, &sig, pri_pk, NULL, sub_pk, pri_psk, 0x18,
                             0, timestamp, 0,