scd,openpgp: Switch key attributes between RSA and ECC in writekey.

* common/sexputil.c (get_rsa_pk_from_canon_sexp): Also allow private
keys.
(pubkey_algo_string): Ditto.
* scd/app-openpgp.c (do_writekey): Switch key attributes
--

The scd WRITEKEY command for OpenPGP cards missed proper support to
aautomagically switch key attributes based on the new key.  We had
this only in GENKEY.

GnuPG-bug-id: 6378

2 files changed, 34 insertions, 6 deletions

diff --git a/common/sexputil.c b/common/sexputil.c
index b7ddea8fc..29fe508b6 100644
--- a/common/sexputil.c
+++ b/common/sexputil.c
@@ -536,7 +536,8 @@ get_rsa_pk_from_canon_sexp (const unsigned char *keydata, size_t keydatalen,
     return err;
   if ((err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen)))
     return err;
-  if (!tok || toklen != 10 || memcmp ("public-key", tok, toklen))
+  if (!tok || !((toklen == 10 && !memcmp ("public-key", tok, toklen))
+                || (toklen == 11 && !memcmp ("private-key", tok, toklen))))
     return gpg_error (GPG_ERR_BAD_PUBKEY);
   if ((err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen)))
     return err;
@@ -1075,6 +1076,8 @@ pubkey_algo_string (gcry_sexp_t s_pkey, enum gcry_pk_algos *r_algoid)
 
   l1 = gcry_sexp_find_token (s_pkey, "public-key", 0);
   if (!l1)
+    l1 = gcry_sexp_find_token (s_pkey, "private-key", 0);
+  if (!l1)
     return xtrystrdup ("E_no_key");
   {
     gcry_sexp_t l_tmp = gcry_sexp_cadr (l1);
diff --git a/scd/app-openpgp.c b/scd/app-openpgp.c
index f5d0b5111..d3f460106 100644
--- a/scd/app-openpgp.c
+++ b/scd/app-openpgp.c
@@ -4824,6 +4824,7 @@ do_writekey (app_t app, ctrl_t ctrl,
   const unsigned char *buf, *tok;
   size_t buflen, toklen;
   int depth;
+  char *algostr = NULL;
 
   (void)ctrl;
 
@@ -4866,17 +4867,41 @@ do_writekey (app_t app, ctrl_t ctrl,
     goto leave;
   if ((err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen)))
     goto leave;
-  if (tok && toklen == 3 && memcmp ("rsa", tok, toklen) == 0)
-    err = rsa_writekey (app, ctrl, pincb, pincb_arg, keyno, buf, buflen, depth);
-  else if (tok && toklen == 3 && memcmp ("ecc", tok, toklen) == 0)
-    err = ecc_writekey (app, ctrl, pincb, pincb_arg, keyno, buf, buflen, depth);
+
+  if (tok && toklen == 3 && (!memcmp ("rsa", tok, toklen)
+                             || !memcmp ("ecc", tok, toklen)))
+    {
+      gcry_sexp_t stmp;
+      if (!gcry_sexp_new (&stmp, keydata, keydatalen, 0))
+        algostr = pubkey_algo_string (stmp, NULL);
+      else
+        algostr = NULL;
+      gcry_sexp_release (stmp);
+      if (app->app_local->keyattr[keyno].keyalgo && algostr
+          && strcmp (app->app_local->keyattr[keyno].keyalgo, algostr))
+        {
+          log_info ("openpgp: changing key attribute from %s to %s\n",
+                    app->app_local->keyattr[keyno].keyalgo, algostr);
+          err = change_keyattr_from_string (app, ctrl, pincb, pincb_arg,
+                                            keyid, algostr, NULL, 0);
+          if (err)
+            return err;
+        }
+
+      if (*tok == 'r')
+        err = rsa_writekey (app, ctrl, pincb, pincb_arg, keyno,
+                            buf,buflen,depth);
+      else
+        err = ecc_writekey (app, ctrl, pincb, pincb_arg, keyno,
+                            buf, buflen, depth);
+    }
   else
     {
       err = gpg_error (GPG_ERR_WRONG_PUBKEY_ALGO);
-      goto leave;
     }
 
  leave:
+  xfree (algostr);
   return err;
 }