common: Extend the openpgp_curve_to_oid function.

* common/openpgp-oid.c (openpgp_curve_to_oid): Add optional arg R_NBITS.
Change all callers.
--

In particular for ed25519 and cv25519 it is quite useful to have an
ability to get the required algorithm.

9 files changed, 27 insertions, 16 deletions

diff --git a/common/openpgp-oid.c b/common/openpgp-oid.c
index 925384f3e..8fda23028 100644
--- a/common/openpgp-oid.c
+++ b/common/openpgp-oid.c
@@ -351,13 +351,17 @@ openpgp_oid_is_cv25519 (gcry_mpi_t a)
 
 /* Map the Libgcrypt ECC curve NAME to an OID.  If R_NBITS is not NULL
    store the bit size of the curve there.  Returns NULL for unknown
-   curve names.  */
+   curve names.  If R_ALGO is not NULL and a specific ECC algorithm is
+   required for this curve its OpenPGP algorithm number is stored
+   there; otherwise 0 is stored which indicates that ECDSA or ECDH can
+   be used. */
 const char *
-openpgp_curve_to_oid (const char *name, unsigned int *r_nbits)
+openpgp_curve_to_oid (const char *name, unsigned int *r_nbits, int *r_algo)
 {
   int i;
   unsigned int nbits = 0;
   const char *oidstr = NULL;
+  int algo = 0;
 
   if (name)
     {
@@ -367,6 +371,7 @@ openpgp_curve_to_oid (const char *name, unsigned int *r_nbits)
           {
             oidstr = oidtable[i].oidstr;
             nbits  = oidtable[i].nbits;
+            algo   = oidtable[i].pubkey_algo;
             break;
           }
       if (!oidtable[i].name)
@@ -378,6 +383,7 @@ openpgp_curve_to_oid (const char *name, unsigned int *r_nbits)
               {
                 oidstr = oidtable[i].oidstr;
                 nbits  = oidtable[i].nbits;
+                algo   = oidtable[i].pubkey_algo;
                 break;
               }
         }
@@ -385,6 +391,8 @@ openpgp_curve_to_oid (const char *name, unsigned int *r_nbits)
 
   if (r_nbits)
     *r_nbits = nbits;
+  if (r_algo)
+    *r_algo = algo;
   return oidstr;
 }
 
diff --git a/common/sexputil.c b/common/sexputil.c
index f99bc3b18..3ed95e43b 100644
--- a/common/sexputil.c
+++ b/common/sexputil.c
@@ -623,7 +623,7 @@ pubkey_algo_string (gcry_sexp_t s_pkey, enum gcry_pk_algos *r_algoid)
     {
       const char *curve = gcry_pk_get_curve (s_pkey, 0, NULL);
       const char *name = openpgp_oid_to_curve
-        (openpgp_curve_to_oid (curve, NULL), 0);
+        (openpgp_curve_to_oid (curve, NULL, NULL), 0);
 
       if (name)
         result = xtrystrdup (name);
diff --git a/common/util.h b/common/util.h
index a6bab2415..64d6c1627 100644
--- a/common/util.h
+++ b/common/util.h
@@ -238,7 +238,8 @@ int openpgp_oidbuf_is_ed25519 (const void *buf, size_t len);
 int openpgp_oid_is_ed25519 (gcry_mpi_t a);
 int openpgp_oidbuf_is_cv25519 (const void *buf, size_t len);
 int openpgp_oid_is_cv25519 (gcry_mpi_t a);
-const char *openpgp_curve_to_oid (const char *name, unsigned int *r_nbits);
+const char *openpgp_curve_to_oid (const char *name,
+                                  unsigned int *r_nbits, int *r_algo);
 const char *openpgp_oid_to_curve (const char *oid, int canon);
 const char *openpgp_oid_or_name_to_curve (const char *oidname, int canon);
 const char *openpgp_enum_curves (int *idxp);
diff --git a/g10/card-util.c b/g10/card-util.c
index cb4dbe5e1..843abd823 100644
--- a/g10/card-util.c
+++ b/g10/card-util.c
@@ -632,7 +632,8 @@ current_card_status (ctrl_t ctrl, estream_t fp,
                 if (info.key_attr[i].curve)
                   {
                     const char *oid;
-                    oid = openpgp_curve_to_oid (info.key_attr[i].curve, NULL);
+                    oid = openpgp_curve_to_oid (info.key_attr[i].curve,
+                                                NULL, NULL);
                     if (oid)
                       curve_for_print = openpgp_oid_to_curve (oid, 0);
                   }
@@ -1545,7 +1546,7 @@ ask_card_keyattr (int keyno, const struct key_attr *current)
       if (curve)
         {
           key_attr->algo = algo;
-          oid_str = openpgp_curve_to_oid (curve, NULL);
+          oid_str = openpgp_curve_to_oid (curve, NULL, NULL);
           key_attr->curve = openpgp_oid_to_curve (oid_str, 0);
         }
       else
diff --git a/g10/export.c b/g10/export.c
index 3517be72c..9160680d7 100644
--- a/g10/export.c
+++ b/g10/export.c
@@ -517,7 +517,7 @@ match_curve_skey_pk (gcry_sexp_t s_key, PKT_public_key *pk)
       log_error ("no curve name\n");
       return gpg_error (GPG_ERR_UNKNOWN_CURVE);
     }
-  oidstr = openpgp_curve_to_oid (curve_str, NULL);
+  oidstr = openpgp_curve_to_oid (curve_str, NULL, NULL);
   if (!oidstr)
     {
       log_error ("no OID known for curve '%s'\n", curve_str);
@@ -1023,7 +1023,7 @@ transfer_format_to_openpgp (gcry_sexp_t s_pgp, PKT_public_key *pk)
           goto leave;
         }
 
-      oidstr = openpgp_curve_to_oid (curve, NULL);
+      oidstr = openpgp_curve_to_oid (curve, NULL, NULL);
       if (!oidstr)
         {
           log_error ("no OID known for curve '%s'\n", curve);
diff --git a/g10/gpg.c b/g10/gpg.c
index 83524b13c..2ac34c9c1 100644
--- a/g10/gpg.c
+++ b/g10/gpg.c
@@ -1879,7 +1879,7 @@ list_config(char *items)
 	  es_printf ("cfg:curveoid:");
           for (iter=0, first=1; (s = openpgp_enum_curves (&iter)); first = 0)
             {
-              s = openpgp_curve_to_oid (s, NULL);
+              s = openpgp_curve_to_oid (s, NULL, NULL);
               es_printf ("%s%s", first?"":";", s? s:"[?]");
             }
 	  es_printf ("\n");
diff --git a/g10/keygen.c b/g10/keygen.c
index 447743fca..06b098822 100644
--- a/g10/keygen.c
+++ b/g10/keygen.c
@@ -1312,7 +1312,7 @@ ecckey_from_sexp (gcry_mpi_t *array, gcry_sexp_t sexp, int algo)
       goto leave;
     }
   gcry_sexp_release (l2);
-  oidstr = openpgp_curve_to_oid (curve, &nbits);
+  oidstr = openpgp_curve_to_oid (curve, &nbits, NULL);
   if (!oidstr)
     {
       /* That can't happen because we used one of the curves
diff --git a/scd/app-openpgp.c b/scd/app-openpgp.c
index 07fbf7474..62ec710bb 100644
--- a/scd/app-openpgp.c
+++ b/scd/app-openpgp.c
@@ -1494,7 +1494,7 @@ ecdh_params (const char *curve)
 {
   unsigned int nbits;
 
-  openpgp_curve_to_oid (curve, &nbits);
+  openpgp_curve_to_oid (curve, &nbits, NULL);
 
   /* See RFC-6637 for those constants.
          0x03: Number of bytes
@@ -1535,7 +1535,7 @@ ecc_read_pubkey (app_t app, ctrl_t ctrl, u32 created_at, int keyno,
     }
 
   curve = app->app_local->keyattr[keyno].ecc.curve;
-  oidstr = openpgp_curve_to_oid (curve, NULL);
+  oidstr = openpgp_curve_to_oid (curve, NULL, NULL);
   err = openpgp_oid_from_str (oidstr, &oid);
   if (err)
     return err;
@@ -3608,7 +3608,7 @@ change_keyattr_from_string (app_t app, ctrl_t ctrl,
       const unsigned char *oidbuf;
       size_t oid_len;
 
-      oidstr = openpgp_curve_to_oid (string+n, NULL);
+      oidstr = openpgp_curve_to_oid (string+n, NULL, NULL);
       if (!oidstr)
         {
           err = gpg_error (GPG_ERR_INV_DATA);
@@ -4115,7 +4115,7 @@ ecc_writekey (app_t app, ctrl_t ctrl,
   else
     algo = PUBKEY_ALGO_ECDSA;
 
-  oidstr = openpgp_curve_to_oid (curve, NULL);
+  oidstr = openpgp_curve_to_oid (curve, NULL, NULL);
   err = openpgp_oid_from_str (oidstr, &oid);
   if (err)
     goto leave;
diff --git a/scd/app-piv.c b/scd/app-piv.c
index 1b3e2e75b..cefc9d997 100644
--- a/scd/app-piv.c
+++ b/scd/app-piv.c
@@ -2927,9 +2927,10 @@ writekey_ecc (app_t app, data_object_t dobj, int keyref,
           name[toklen] = 0;
           /* Canonicalize the curve name.  We use the openpgp
            * functions here because Libgcrypt has no generic curve
-           * alias lookup feature and the PIV suppotred curves alre
+           * alias lookup feature and the PIV supported curves are
            * also supported by OpenPGP.  */
-          xname = openpgp_oid_to_curve (openpgp_curve_to_oid (name, NULL), 0);
+          xname = openpgp_oid_to_curve (openpgp_curve_to_oid (name, NULL, NULL),
+                                        0);
           xfree (name);
 
           if (xname && !strcmp (xname, "nistp256"))