Add hack to allow using an "ecc" key for "ecdsa" or "ecdh".

* cipher/pubkey.c (sexp_to_key): Add optional arg USE.
(gcry_pk_encrypt, gcry_pk_decrypt): Call sexp_to_key with usage sign.
(gcry_pk_sign, gcry_pk_verify): Call sexp_to_key with usage encrypt.
* tests/basic.c (show_sexp): New.
(check_pubkey_sign): Print test number and add cases for ecc.
(check_pubkey_sign_ecdsa): New.
(do_check_one_pubkey): Divert to new function.
--

The problem we try to address is that in the mdoule specs both, ECDSA
and ECDH have the same alias name "ecc".  This patch allows to use for
example gcry_pk_verify with a key that has only "ecc" in it.

Signed-off-by: Werner Koch <wk@gnupg.org>

1 files changed, 33 insertions, 17 deletions

diff --git a/cipher/pubkey.c b/cipher/pubkey.c
index 00317b5b..378e0724 100644
--- a/cipher/pubkey.c
+++ b/cipher/pubkey.c
@@ -2002,7 +2002,8 @@ sexp_elements_extract_ecc (gcry_sexp_t key_sexp, const char *element_names,
  * The <mpi> are expected to be in GCRYMPI_FMT_USG
  */
 static gcry_err_code_t
-sexp_to_key (gcry_sexp_t sexp, int want_private, const char *override_elems,
+sexp_to_key (gcry_sexp_t sexp, int want_private, int use,
+             const char *override_elems,
              gcry_mpi_t **retarray, gcry_module_t *retalgo, int *r_is_ecc)
 {
   gcry_err_code_t err = 0;
@@ -2031,19 +2032,31 @@ sexp_to_key (gcry_sexp_t sexp, int want_private, const char *override_elems,
       return GPG_ERR_INV_OBJ;      /* Invalid structure of object. */
     }
 
-  ath_mutex_lock (&pubkeys_registered_lock);
-  module = gcry_pk_lookup_name (name);
-  ath_mutex_unlock (&pubkeys_registered_lock);
-
   /* Fixme: We should make sure that an ECC key is always named "ecc"
      and not "ecdsa".  "ecdsa" should be used for the signature
      itself.  We need a function to test whether an algorithm given
      with a key is compatible with an application of the key (signing,
      encryption).  For RSA this is easy, but ECC is the first
-     algorithm which has many flavours.  */
-  is_ecc = ( !strcmp (name, "ecdsa")
-             || !strcmp (name, "ecdh")
-             || !strcmp (name, "ecc") );
+     algorithm which has many flavours.
+
+     We use an ugly hack here to decide whether to use ecdsa or ecdh.
+  */
+  if (!strcmp (name, "ecc"))
+    is_ecc = 2;
+  else if (!strcmp (name, "ecdsa") || !strcmp (name, "ecdh"))
+    is_ecc = 1;
+  else
+    is_ecc = 0;
+
+  ath_mutex_lock (&pubkeys_registered_lock);
+  if (is_ecc == 2 && (use & GCRY_PK_USAGE_SIGN))
+    module = gcry_pk_lookup_name ("ecdsa");
+  else if (is_ecc == 2 && (use & GCRY_PK_USAGE_ENCR))
+    module = gcry_pk_lookup_name ("ecdh");
+  else
+    module = gcry_pk_lookup_name (name);
+  ath_mutex_unlock (&pubkeys_registered_lock);
+
   gcry_free (name);
 
   if (!module)
@@ -2866,7 +2879,7 @@ gcry_pk_encrypt (gcry_sexp_t *r_ciph, gcry_sexp_t s_data, gcry_sexp_t s_pkey)
   REGISTER_DEFAULT_PUBKEYS;
 
   /* Get the key. */
-  rc = sexp_to_key (s_pkey, 0, NULL, &pkey, &module, NULL);
+  rc = sexp_to_key (s_pkey, 0, GCRY_PK_USAGE_ENCR, NULL, &pkey, &module, NULL);
   if (rc)
     goto leave;
 
@@ -3039,7 +3052,8 @@ gcry_pk_decrypt (gcry_sexp_t *r_plain, gcry_sexp_t s_data, gcry_sexp_t s_skey)
 
   REGISTER_DEFAULT_PUBKEYS;
 
-  rc = sexp_to_key (s_skey, 1, NULL, &skey, &module_key, NULL);
+  rc = sexp_to_key (s_skey, 1, GCRY_PK_USAGE_ENCR, NULL,
+                    &skey, &module_key, NULL);
   if (rc)
     goto leave;
 
@@ -3168,7 +3182,8 @@ gcry_pk_sign (gcry_sexp_t *r_sig, gcry_sexp_t s_hash, gcry_sexp_t s_skey)
 
   REGISTER_DEFAULT_PUBKEYS;
 
-  rc = sexp_to_key (s_skey, 1, NULL, &skey, &module, &is_ecc);
+  rc = sexp_to_key (s_skey, 1, GCRY_PK_USAGE_SIGN, NULL,
+                    &skey, &module, &is_ecc);
   if (rc)
     goto leave;
 
@@ -3302,7 +3317,8 @@ gcry_pk_verify (gcry_sexp_t s_sig, gcry_sexp_t s_hash, gcry_sexp_t s_pkey)
 
   REGISTER_DEFAULT_PUBKEYS;
 
-  rc = sexp_to_key (s_pkey, 0, NULL, &pkey, &module_key, NULL);
+  rc = sexp_to_key (s_pkey, 0, GCRY_PK_USAGE_SIGN, NULL,
+                    &pkey, &module_key, NULL);
   if (rc)
     goto leave;
 
@@ -3375,7 +3391,7 @@ gcry_pk_testkey (gcry_sexp_t s_key)
   REGISTER_DEFAULT_PUBKEYS;
 
   /* Note we currently support only secret key checking. */
-  rc = sexp_to_key (s_key, 1, NULL, &key, &module, NULL);
+  rc = sexp_to_key (s_key, 1, 0, NULL, &key, &module, NULL);
   if (! rc)
     {
       rc = pubkey_check_secret_key (module->mod_id, key);
@@ -3708,9 +3724,9 @@ gcry_pk_get_nbits (gcry_sexp_t key)
      ECC we would only need to look at P and stop parsing right
      away.  */
 
-  rc = sexp_to_key (key, 0, NULL, &keyarr, &module, NULL);
+  rc = sexp_to_key (key, 0, 0, NULL, &keyarr, &module, NULL);
   if (rc == GPG_ERR_INV_OBJ)
-    rc = sexp_to_key (key, 1, NULL, &keyarr, &module, NULL);
+    rc = sexp_to_key (key, 1, 0, NULL, &keyarr, &module, NULL);
   if (rc)
     return 0; /* Error - 0 is a suitable indication for that. */
 
@@ -3881,7 +3897,7 @@ gcry_pk_get_curve (gcry_sexp_t key, int iterator, unsigned int *r_nbits)
       /* Get the key.  We pass the names of the parameters for
          override_elems; this allows to call this function without the
          actual public key parameter.  */
-      if (sexp_to_key (key, want_private, "pabgn", &pkey, &module, NULL))
+      if (sexp_to_key (key, want_private, 0, "pabgn", &pkey, &module, NULL))
         goto leave;
     }
   else