gpg: Prepare parser for the new attestation certificates.

* common/openpgpdefs.h (SIGSUBPKT_ATTST_SIGS): New.
* g10/keydb.h (IS_ATTST_SIGS): New.
(IS_CERT): Include the new one.
* g10/sign.c (mk_notation_policy_etc): Do not put notations into
attestation key signatures.
* g10/parse-packet.c (dump_sig_subpkt): Add new arg digest_algo.
Print the attestation sigs.
(parse_one_sig_subpkt): Support SIGSUBPKT_ATTST_SIGS.
(can_handle_critical): Ditto.
(enum_sig_subpkt): Pass digest algo to dump_sig_subpkt.
--

This change allows to list the new subpacket with --list-packets.
Example output:

  :signature packet: algo 22, keyid C694723A1370EAB1
          version 4, created 1567097576, md5len 0, sigclass 0x16
          digest algo 8, begin of digest ff 0c
          hashed subpkt 2 len 4 (sig created 2019-08-29)
          hashed subpkt 37 len 32 (attst-sigs: 1
                                   A794C6E9CCFE2F34C67E07[...])
          hashed subpkt 33 len 21 (issuer fpr v4 156A3872[...])
          subpkt 16 len 8 (issuer key ID C694723A1370EAB1)
          data: [256 bits]
          data: [256 bits]

GnuPG-bug-id: 4694
Signed-off-by: Werner Koch <wk@gnupg.org>

common/openpgpdefs.h

@@ -119,6 +119,8 @@ typedef enum
     SIGSUBPKT_ISSUER_FPR    = 33, /* Issuer fingerprint. */
     SIGSUBPKT_PREF_AEAD     = 34, /* Preferred AEAD algorithms. */
 
+    SIGSUBPKT_ATTST_SIGS    = 37, /* Attested Certifications.  */
+
     SIGSUBPKT_FLAG_CRITICAL = 128
   }
 sigsubpkttype_t;

g10/keydb.h

@@ -29,11 +29,17 @@
 /* What qualifies as a certification (key-signature in contrast to a
  * data signature)?  Note that a back signature is special and can be
  * made by key and data signatures capable subkeys.) */
-#define IS_CERT(s)       (IS_KEY_SIG(s) || IS_UID_SIG(s) || IS_SUBKEY_SIG(s) \
+#define IS_CERT(s)       (IS_KEY_SIG(s)       \
-                         || IS_KEY_REV(s) || IS_UID_REV(s) || IS_SUBKEY_REV(s))
+                          || IS_UID_SIG(s)    \
+                          || IS_SUBKEY_SIG(s) \
+                          || IS_KEY_REV(s)    \
+                          || IS_UID_REV(s)    \
+                          || IS_SUBKEY_REV(s) \
+                          || IS_ATTST_SIGS(s) )
 #define IS_SIG(s)        (!IS_CERT(s))
 #define IS_KEY_SIG(s)    ((s)->sig_class == 0x1f)
 #define IS_UID_SIG(s)    (((s)->sig_class & ~3) == 0x10)
+#define IS_ATTST_SIGS(s) ((s)->sig_class == 0x16)
 #define IS_SUBKEY_SIG(s) ((s)->sig_class == 0x18)
 #define IS_BACK_SIG(s)   ((s)->sig_class == 0x19)
 #define IS_KEY_REV(s)    ((s)->sig_class == 0x20)

g10/parse-packet.c

@@ -1360,17 +1360,20 @@ parse_pubkeyenc (IOBUF inp, int pkttype, unsigned long pktlen,
 
 
 /* Dump a subpacket to LISTFP.  BUFFER contains the subpacket in
-   question and points to the type field in the subpacket header (not
+ * question and points to the type field in the subpacket header (not
-   the start of the header).  TYPE is the subpacket's type with the
+ * the start of the header).  TYPE is the subpacket's type with the
-   critical bit cleared.  CRITICAL is the value of the CRITICAL bit.
+ * critical bit cleared.  CRITICAL is the value of the CRITICAL bit.
-   BUFLEN is the length of the buffer and LENGTH is the length of the
+ * BUFLEN is the length of the buffer and LENGTH is the length of the
-   subpacket according to the subpacket's header.  */
+ * subpacket according to the subpacket's header.  DIGEST_ALGO is the
+ * digest algo of the signature.  */
 static void
 dump_sig_subpkt (int hashed, int type, int critical,
-		 const byte * buffer, size_t buflen, size_t length)
+		 const byte * buffer, size_t buflen, size_t length,
+                 int digest_algo)
 {
   const char *p = NULL;
   int i;
+  int nprinted;
 
   /* The CERT has warning out with explains how to use GNUPG to detect
    * the ARRs - we print our old message here when it is a faked ARR
@@ -1388,9 +1391,11 @@ dump_sig_subpkt (int hashed, int type, int critical,
   buffer++;
   length--;
 
-  es_fprintf (listfp, "\t%s%ssubpkt %d len %u (",	/*) */
+  nprinted = es_fprintf (listfp, "\t%s%ssubpkt %d len %u (",	/*) */
                          critical ? "critical " : "",
                          hashed ? "hashed " : "", type, (unsigned) length);
+  if (nprinted < 1)
+    nprinted = 1; /*(we use (nprinted-1) later.)*/
   if (length > buflen)
     {
       es_fprintf (listfp, "too short: buffer is only %u)\n", (unsigned) buflen);
@@ -1585,6 +1590,32 @@ dump_sig_subpkt (int hashed, int type, int critical,
                     buffer[0] == 3 ? buffer[15] : buffer[2],
                     buffer[0] == 3 ? buffer[16] : buffer[3]);
       break;
+
+    case SIGSUBPKT_ATTST_SIGS:
+      {
+        unsigned int hlen;
+
+	es_fputs ("attst-sigs: ", listfp);
+        hlen = gcry_md_get_algo_dlen (map_md_openpgp_to_gcry (digest_algo));
+	if (!hlen)
+	  p = "[unknown digest algo]";
+        else if ((length % hlen))
+	  p = "[invalid length]";
+	else
+	  {
+            es_fprintf (listfp, "%d", length/hlen);
+            while (length)
+              {
+                es_fprintf (listfp, "\n\t%*s", nprinted-1, "");
+                es_write_hexstring (listfp, buffer, hlen, 0, NULL);
+                buffer += hlen;
+                length -= hlen;
+              }
+	  }
+      }
+      break;
+
+
     default:
       if (type >= 100 && type <= 110)
 	p = "experimental / private subpacket";
@@ -1627,6 +1658,7 @@ parse_one_sig_subpkt (const byte * buffer, size_t n, int type)
     case SIGSUBPKT_PREF_KS:
     case SIGSUBPKT_FEATURES:
     case SIGSUBPKT_REGEXP:
+    case SIGSUBPKT_ATTST_SIGS:
       return 0;
     case SIGSUBPKT_SIGNATURE:
     case SIGSUBPKT_EXPORTABLE:
@@ -1721,6 +1753,7 @@ can_handle_critical (const byte * buffer, size_t n, int type)
     case SIGSUBPKT_FEATURES:
     case SIGSUBPKT_TRUST:
     case SIGSUBPKT_REGEXP:
+    case SIGSUBPKT_ATTST_SIGS:
       /* Is it enough to show the policy or keyserver? */
     case SIGSUBPKT_POLICY:
     case SIGSUBPKT_PREF_KS:
@@ -1812,7 +1845,7 @@ enum_sig_subpkt (PKT_signature *sig, int want_hashed, sigsubpkttype_t reqtype,
 	}
       else if (reqtype < 0) /* List packets.  */
 	dump_sig_subpkt (reqtype == SIGSUBPKT_LIST_HASHED,
-			 type, *critical, buffer, buflen, n);
+			 type, *critical, buffer, buflen, n, sig->digest_algo);
       else if (type == reqtype) /* Found.  */
 	{
 	  buffer++;

g10/sign.c

@@ -86,7 +86,9 @@ mk_notation_policy_etc (PKT_signature *sig,
   args.pksk = pksk;
 
   /* Notation data. */
-  if (IS_SIG(sig) && opt.sig_notations)
+  if (IS_ATTST_SIGS(sig))
+    ;
+  else if (IS_SIG(sig) && opt.sig_notations)
     nd = opt.sig_notations;
   else if (IS_CERT(sig) && opt.cert_notations)
     nd = opt.cert_notations;
@@ -113,7 +115,9 @@ mk_notation_policy_etc (PKT_signature *sig,
     }
 
   /* Set policy URL. */
-  if (IS_SIG(sig) && opt.sig_policy_url)
+  if (IS_ATTST_SIGS(sig))
+    ;
+  else if (IS_SIG(sig) && opt.sig_policy_url)
     pu = opt.sig_policy_url;
   else if (IS_CERT(sig) && opt.cert_policy_url)
     pu = opt.cert_policy_url;