[TESTING] Curve25519 encryption support (update)

NIIBE Yutaka gniibe at fsij.org
Wed Jul 8 02:42:30 CEST 2015


Hello,

Here is a patch I am testing for Curve25519 encryption support (which
requires libgcrypt change for Curve25519, and Gnuk master branch).

I tested:

    (1) key generation
    (2) encryption
    (3) decryption
    (4) keytocard
    (5) asking decryption on card

There are things we need to decide: OID, algo ID, and format.
Currently, I use:

     OID: 1.3.6.1.4.1.3029.1.5.1
     algo ID: ECC = 18 (not 22 nor 23)
     Public key OpenPGP format: prefix 0x40 and native little endian
     Libgcrypt SEXP format: Use (flags eddsa) to specify DJB format/processing
                            (flags comp) for prefix 0x40

It works for me, but the code is not mature enough.

diff --git a/agent/cvt-openpgp.c b/agent/cvt-openpgp.c
index 562179b..34c942b 100644
--- a/agent/cvt-openpgp.c
+++ b/agent/cvt-openpgp.c
@@ -83,14 +83,29 @@ get_keygrip (int pubkey_algo, const char *curve, gcry_mpi_t *pkey,
     case GCRY_PK_ECC:
       if (!curve)
         err = gpg_error (GPG_ERR_BAD_SECKEY);
-      else if (!strcmp (curve, openpgp_curve_to_oid ("Ed25519", NULL)))
-        err = gcry_sexp_build (&s_pkey, NULL,
-                               "(public-key(ecc(curve %s)(flags eddsa)(q%m)))",
-                               "Ed25519", pkey[0]);
       else
-        err = gcry_sexp_build (&s_pkey, NULL,
-                               "(public-key(ecc(curve %s)(q%m)))",
-                               curve, pkey[0]);
+        {
+          int with_eddsa_flag = 0;
+          const char *curve_name;
+
+          curve_name = "Ed25519";
+          if (!strcmp (curve, openpgp_curve_to_oid (curve_name, NULL)))
+            with_eddsa_flag = 1;
+          else
+            {
+              curve_name = "Curve25519";
+              if (!strcmp (curve, openpgp_curve_to_oid (curve_name, NULL)))
+                with_eddsa_flag = 1;
+            }
+          if (with_eddsa_flag)
+            err = gcry_sexp_build (&s_pkey, NULL,
+                                   "(public-key(ecc(curve %s)(flags eddsa)(q%m)))",
+                                   curve_name, pkey[0]);
+          else
+            err = gcry_sexp_build (&s_pkey, NULL,
+                                   "(public-key(ecc(curve %s)(q%m)))",
+                                   curve, pkey[0]);
+        }
       break;

     default:
@@ -146,19 +161,32 @@ convert_secret_key (gcry_sexp_t *r_key, int pubkey_algo, gcry_mpi_t *skey,
     case GCRY_PK_ECC:
       if (!curve)
         err = gpg_error (GPG_ERR_BAD_SECKEY);
-      else if (!strcmp (curve, openpgp_curve_to_oid ("Ed25519", NULL)))
+      else
         {
-          /* Do not store the OID as name but the real name and the
-             EdDSA flag.  */
-          err = gcry_sexp_build (&s_skey, NULL,
-                                 "(private-key(ecc(curve%s)(flags eddsa)"
-                                 "(q%m)(d%m)))",
-                                 "Ed25519", skey[0], skey[1]);
+          int with_eddsa_flag = 0;
+          const char *curve_name;
+
+          curve_name = "Ed25519";
+          if (!strcmp (curve, openpgp_curve_to_oid (curve_name, NULL)))
+            with_eddsa_flag = 1;
+          else
+            {
+              curve_name = "Curve25519";
+              if (!strcmp (curve, openpgp_curve_to_oid (curve_name, NULL)))
+                with_eddsa_flag = 1;
+            }
+          if (with_eddsa_flag)
+            /* Do not store the OID as name but the real name and the
+               EdDSA flag.  */
+            err = gcry_sexp_build (&s_skey, NULL,
+                                   "(private-key(ecc(curve%s)(flags eddsa)"
+                                   "(q%m)(d%m)))",
+                                   "Ed25519", skey[0], skey[1]);
+          else
+            err = gcry_sexp_build (&s_skey, NULL,
+                                   "(private-key(ecc(curve%s)(q%m)(d%m)))",
+                                   curve, skey[0], skey[1]);
         }
-      else
-        err = gcry_sexp_build (&s_skey, NULL,
-                               "(private-key(ecc(curve%s)(q%m)(d%m)))",
-                               curve, skey[0], skey[1]);
       break;

     default:
@@ -216,22 +244,35 @@ convert_transfer_key (gcry_sexp_t *r_key, int pubkey_algo, gcry_mpi_t *skey,
     case GCRY_PK_ECC:
       if (!curve)
         err = gpg_error (GPG_ERR_BAD_SECKEY);
-      else if (!strcmp (curve, openpgp_curve_to_oid ("Ed25519", NULL)))
+      else
         {
-          /* Do not store the OID as name but the real name and the
-             EdDSA flag.  */
-          err = gcry_sexp_build
-            (&s_skey, NULL,
-             "(protected-private-key(ecc(curve%s)(flags eddsa)(q%m)"
-             "(protected openpgp-native%S)))",
-             "Ed25519", skey[0], transfer_key);
+          int with_eddsa_flag = 0;
+          const char *curve_name;
+
+          curve_name = "Ed25519";
+          if (!strcmp (curve, openpgp_curve_to_oid (curve_name, NULL)))
+            with_eddsa_flag = 1;
+          else
+            {
+              curve_name = "Curve25519";
+              if (!strcmp (curve, openpgp_curve_to_oid (curve_name, NULL)))
+                with_eddsa_flag = 1;
+            }
+          if (with_eddsa_flag)
+            /* Do not store the OID as name but the real name and the
+               EdDSA flag.  */
+            err = gcry_sexp_build
+              (&s_skey, NULL,
+               "(protected-private-key(ecc(curve%s)(flags eddsa)(q%m)"
+               "(protected openpgp-native%S)))",
+               curve_name, skey[0], transfer_key);
+          else
+            err = gcry_sexp_build
+              (&s_skey, NULL,
+               "(protected-private-key(ecc(curve%s)(q%m)"
+               "(protected openpgp-native%S)))",
+               curve, skey[0], transfer_key);
         }
-      else
-        err = gcry_sexp_build
-          (&s_skey, NULL,
-           "(protected-private-key(ecc(curve%s)(q%m)"
-           "(protected openpgp-native%S)))",
-           curve, skey[0], transfer_key);
       break;

     default:
diff --git a/common/openpgp-oid.c b/common/openpgp-oid.c
index 7a75801..92622ce 100644
--- a/common/openpgp-oid.c
+++ b/common/openpgp-oid.c
@@ -45,6 +45,7 @@ static struct {
   const char *alias;  /* NULL or alternative name of the curve.  */
 } oidtable[] = {

+  { "Curve25519",      "1.3.6.1.4.1.3029.1.5.1", 255, "curve25519" },
   { "Ed25519",         "1.3.6.1.4.1.11591.15.1", 255, "ed25519" },

   { "NIST P-256",      "1.2.840.10045.3.1.7",    256, "nistp256" },
@@ -65,6 +66,10 @@ static struct {
 static const char oid_ed25519[] =
   { 0x09, 0x2b, 0x06, 0x01, 0x04, 0x01, 0xda, 0x47, 0x0f, 0x01 };

+/* The OID for Curve25519 in OpenPGP format.  */
+static const char oid_curve25519[] =
+  { 0x0a, 0x2b, 0x06, 0x01, 0x04, 0x01, 0x97, 0x55, 0x01, 0x05, 0x01 };
+

 /* Helper for openpgp_oid_from_str.  */
 static size_t
@@ -291,6 +296,22 @@ openpgp_oid_is_ed25519 (gcry_mpi_t a)
 }


+int
+openpgp_oid_is_curve25519 (gcry_mpi_t a)
+{
+  const unsigned char *buf;
+  unsigned int nbits;
+  size_t n;
+
+  if (!a || !gcry_mpi_get_flag (a, GCRYMPI_FLAG_OPAQUE))
+    return 0;
+
+  buf = gcry_mpi_get_opaque (a, &nbits);
+  n = (nbits+7)/8;
+  return (n == DIM (oid_curve25519)
+          && !memcmp (buf, oid_curve25519, DIM (oid_curve25519)));
+}
+

 /* 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
diff --git a/common/util.h b/common/util.h
index b92d78c..2851cfd 100644
--- a/common/util.h
+++ b/common/util.h
@@ -318,6 +318,7 @@ size_t percent_unescape_inplace (char *string, int nulrepl);
 gpg_error_t openpgp_oid_from_str (const char *string, gcry_mpi_t *r_mpi);
 char *openpgp_oid_to_str (gcry_mpi_t a);
 int openpgp_oid_is_ed25519 (gcry_mpi_t a);
+int openpgp_oid_is_curve25519 (gcry_mpi_t a);
 const char *openpgp_curve_to_oid (const char *name, unsigned int *r_nbits);
 const char *openpgp_oid_to_curve (const char *oid);
 const char *openpgp_enum_curves (int *idxp);
diff --git a/g10/ecdh.c b/g10/ecdh.c
index 9576a1c..a1b7ecf 100644
--- a/g10/ecdh.c
+++ b/g10/ecdh.c
@@ -134,9 +134,12 @@ pk_ecdh_encrypt_with_shared_point (int is_encrypt, gcry_mpi_t shared_mpi,
       }

     secret_x_size = (nbits+7)/8;
-    assert (nbytes > secret_x_size);
-    memmove (secret_x, secret_x+1, secret_x_size);
-    memset (secret_x+secret_x_size, 0, nbytes-secret_x_size);
+    assert (nbytes >= secret_x_size);
+    if ((nbytes & 1))
+      /* Remove the "04" prefix of non-compressed format.  */
+      memmove (secret_x, secret_x+1, secret_x_size);
+    if (nbytes - secret_x_size)
+      memset (secret_x+secret_x_size, 0, nbytes-secret_x_size);

     if (DBG_CRYPTO)
       log_printhex ("ECDH shared secret X is:", secret_x, secret_x_size );
diff --git a/g10/keygen.c b/g10/keygen.c
index 796d18f..3eb8e73 100644
--- a/g10/keygen.c
+++ b/g10/keygen.c
@@ -1520,6 +1520,13 @@ gen_ecc (int algo, const char *curve, kbnode_t pub_root,
        (((keygen_flags & KEYGEN_FLAG_TRANSIENT_KEY)
          && (keygen_flags & KEYGEN_FLAG_NO_PROTECTION))?
         " transient-key" : ""));
+  else if (algo == PUBKEY_ALGO_ECDH && !strcmp (curve, "Curve25519"))
+    keyparms = xtryasprintf
+      ("(genkey(ecc(curve %zu:%s)(flags eddsa comp%s)))",
+       strlen (curve), curve,
+       (((keygen_flags & KEYGEN_FLAG_TRANSIENT_KEY)
+         && (keygen_flags & KEYGEN_FLAG_NO_PROTECTION))?
+        " transient-key" : ""));
   else
     keyparms = xtryasprintf
       ("(genkey(ecc(curve %zu:%s)(flags nocomp%s)))",
@@ -2125,7 +2132,7 @@ ask_keysize (int algo, unsigned int primary_keysize)
    function may adjust.  Returns a malloced string with the name of
    the curve.  BOTH tells that gpg creates a primary and subkey. */
 static char *
-ask_curve (int *algo, int both)
+ask_curve (int *algo, int *subkey_algo)
 {
   struct {
     const char *name;
@@ -2176,7 +2183,7 @@ ask_curve (int *algo, int both)
         continue;
       if (!gcry_pk_get_curve (keyparms, 0, NULL))
         continue;
-      if (both && curves[idx].fix_curve)
+      if (subkey_algo && curves[idx].fix_curve)
         {
           /* Both Curve 25519 keys are to be created.  Check that
              Libgcrypt also supports the real Curve25519.  */
@@ -2241,6 +2248,11 @@ ask_curve (int *algo, int both)
           if ((*algo == PUBKEY_ALGO_ECDSA || *algo == PUBKEY_ALGO_EDDSA)
               && curves[idx].fix_curve)
             {
+              if (subkey_algo && *subkey_algo == PUBKEY_ALGO_ECDSA)
+                {
+                  *subkey_algo = PUBKEY_ALGO_EDDSA;
+                  result = xstrdup ("Ed25519");
+                }
               *algo = PUBKEY_ALGO_EDDSA;
               result = xstrdup ("Ed25519");
             }
@@ -3672,7 +3684,7 @@ generate_keypair (ctrl_t ctrl, int full, const char *fname,
               || algo == PUBKEY_ALGO_EDDSA
               || algo == PUBKEY_ALGO_ECDH)
             {
-              curve = ask_curve (&algo, both);
+              curve = ask_curve (&algo, &subkey_algo);
               r = xmalloc_clear( sizeof *r + 20 );
               r->key = pKEYTYPE;
               sprintf( r->u.value, "%d", algo);
@@ -3743,7 +3755,7 @@ generate_keypair (ctrl_t ctrl, int full, const char *fname,
               || algo == PUBKEY_ALGO_EDDSA
               || algo == PUBKEY_ALGO_ECDH)
             {
-              curve = ask_curve (&algo, 0);
+              curve = ask_curve (&algo, NULL);
               nbits = 0;
               r = xmalloc_clear (sizeof *r + strlen (curve));
               r->key = pKEYCURVE;
@@ -4292,7 +4304,7 @@ generate_subkeypair (ctrl_t ctrl, kbnode_t keyblock)
   else if (algo == PUBKEY_ALGO_ECDSA
            || algo == PUBKEY_ALGO_EDDSA
            || algo == PUBKEY_ALGO_ECDH)
-    curve = ask_curve (&algo, 0);
+    curve = ask_curve (&algo, NULL);
   else
     nbits = ask_keysize (algo, 0);

diff --git a/g10/keyid.c b/g10/keyid.c
index 90d982e..cfdf29d 100644
--- a/g10/keyid.c
+++ b/g10/keyid.c
@@ -761,12 +761,20 @@ keygrip_from_pk (PKT_public_key *pk, unsigned char *array)
     case PUBKEY_ALGO_ECDH:
       {
         char *curve = openpgp_oid_to_str (pk->pkey[0]);
+
         if (!curve)
           err = gpg_error_from_syserror ();
         else
           {
+            int with_eddsa_flag = 0;
+
+            if (pk->pubkey_algo == PUBKEY_ALGO_EDDSA
+                || (pk->pubkey_algo == PUBKEY_ALGO_ECDH
+                    && openpgp_oid_is_curve25519 (pk->pkey[0])))
+              with_eddsa_flag = 1;
+
             err = gcry_sexp_build (&s_pkey, NULL,
-                                   pk->pubkey_algo == PUBKEY_ALGO_EDDSA ?
+                                   with_eddsa_flag ?
                                    "(public-key(ecc(curve%s)(flags eddsa)(q%m)))"
                                    : "(public-key(ecc(curve%s)(q%m)))",
                                    curve, pk->pkey[1]);
diff --git a/g10/misc.c b/g10/misc.c
index 9134b28..8f2d379 100644
--- a/g10/misc.c
+++ b/g10/misc.c
@@ -612,11 +612,11 @@ openpgp_pk_algo_usage ( int algo )
           use = PUBKEY_USAGE_ENC;
           break;
       case PUBKEY_ALGO_DSA:
+      case PUBKEY_ALGO_ECDSA:
           use = PUBKEY_USAGE_CERT | PUBKEY_USAGE_SIG | PUBKEY_USAGE_AUTH;
           break;
-      case PUBKEY_ALGO_ECDSA:
       case PUBKEY_ALGO_EDDSA:
-          use = PUBKEY_USAGE_CERT | PUBKEY_USAGE_SIG | PUBKEY_USAGE_AUTH;
+          use = PUBKEY_USAGE_CERT | PUBKEY_USAGE_SIG | PUBKEY_USAGE_ENC | PUBKEY_USAGE_AUTH;
       default:
           break;
     }
diff --git a/g10/pkglue.c b/g10/pkglue.c
index d72275b..7d78322 100644
--- a/g10/pkglue.c
+++ b/g10/pkglue.c
@@ -228,9 +228,13 @@ pk_encrypt (pubkey_algo_t algo, gcry_mpi_t *resarr, gcry_mpi_t data,
             rc = gpg_error_from_syserror ();
           else
             {
+              int with_eddsa_flag = openpgp_oid_is_curve25519 (pkey[0]);
+
               /* Now use the ephemeral secret to compute the shared point.  */
               rc = gcry_sexp_build (&s_pkey, NULL,
-                                    "(public-key(ecdh(curve%s)(q%m)))",
+                                    with_eddsa_flag ?
+                                    "(public-key(ecdh(curve%s)(flags eddsa)(q%m)))"
+                                    : "(public-key(ecdh(curve%s)(q%m)))",
                                     curve, pkey[1]);
               xfree (curve);
               /* Put K into a simplified S-expression.  */
diff --git a/g10/pubkey-enc.c b/g10/pubkey-enc.c
index cb834af..fd7f812 100644
--- a/g10/pubkey-enc.c
+++ b/g10/pubkey-enc.c
@@ -250,8 +250,8 @@ get_it (PKT_pubkey_enc *enc, DEK *dek, PKT_public_key *sk, u32 *keyid)
       if(err)
         goto leave;

-      /* Reuse NFRAME, which size is sufficient to include the session key.  */
-      err = gcry_mpi_print (GCRYMPI_FMT_USG, frame, nframe, &nframe, decoded);
+      xfree (frame);
+      err = gcry_mpi_aprint (GCRYMPI_FMT_USG, &frame, &nframe, decoded);
       mpi_release (decoded);
       if (err)
         goto leave;
diff --git a/scd/app-openpgp.c b/scd/app-openpgp.c
index f5911f3..81e1590 100644
--- a/scd/app-openpgp.c
+++ b/scd/app-openpgp.c
@@ -151,6 +151,7 @@ enum
     CURVE_NIST_P521,
     CURVE_SEC_P256K1,
     CURVE_ED25519,
+    CURVE_CURVE25519,
     CURVE_UNKNOWN,
   };

@@ -242,9 +243,6 @@ struct app_local_s {
       struct {
         int curve;
       } ecc;
-      struct {
-        int curve;
-      } eddsa;
     };
    } keyattr[3];
 };
@@ -950,6 +948,11 @@ get_ecc_key_parameters (int curve, int *r_n_bits, const char **r_curve_oid)
       *r_n_bits = 255;
       *r_curve_oid = "1.3.6.1.4.1.11591.15.1";
     }
+  else if (curve == CURVE_CURVE25519)
+    {
+      *r_n_bits = 255;
+      *r_curve_oid = "1.3.6.1.4.1.3029.1.5.1";
+    }
   else
     {
       *r_n_bits = 0;
@@ -981,13 +984,13 @@ send_key_attr (ctrl_t ctrl, app_t app, const char *keyword, int number)
     }
   else if (app->app_local->keyattr[number].key_type == KEY_TYPE_EDDSA)
     {
-      get_ecc_key_parameters (app->app_local->keyattr[number].eddsa.curve,
+      get_ecc_key_parameters (app->app_local->keyattr[number].ecc.curve,
                               &n_bits, &curve_oid);
       snprintf (buffer, sizeof buffer, "%d 22 %u %s",
                 number+1, n_bits, curve_oid);
     }
   else
-    snprintf (buffer, sizeof buffer, "0 0 UNKNOWN");
+    snprintf (buffer, sizeof buffer, "%d 0 0 UNKNOWN", number+1);

   send_status_direct (ctrl, keyword, buffer);
 }
@@ -1304,6 +1307,8 @@ get_curve_name (int curve)
     return "secp256k1";
   else if (curve == CURVE_ED25519)
     return "Ed25519";
+  else if (curve == CURVE_CURVE25519)
+    return "Curve25519";
   else
     return "unknown";
 }
@@ -1477,6 +1482,8 @@ get_public_key (app_t app, int keyno)
     }
   /* Prepend numbers with a 0 if needed.  */
   if (app->app_local->keyattr[keyno].key_type != KEY_TYPE_EDDSA
+      && !(app->app_local->keyattr[keyno].key_type == KEY_TYPE_ECC
+           && app->app_local->keyattr[keyno].ecc.curve == CURVE_CURVE25519)
       && mlen && (*m & 0x80))
     {
       *mbuf = 0;
@@ -1506,72 +1513,36 @@ get_public_key (app_t app, int keyno)
     {
       err = gcry_sexp_build (&s_pkey, NULL, "(public-key(rsa(n%b)(e%b)))",
                              (int)mlen, mbuf, (int)elen, ebuf);
-      if (err)
-        goto leave;
-
-      len = gcry_sexp_sprint (s_pkey, GCRYSEXP_FMT_CANON, NULL, 0);
-      keybuf = xtrymalloc (len);
-      if (!keybuf)
-        {
-          gcry_sexp_release (s_pkey);
-          err = gpg_error_from_syserror ();
-          goto leave;
-        }
-      gcry_sexp_sprint (s_pkey, GCRYSEXP_FMT_CANON, keybuf, len);
-      gcry_sexp_release (s_pkey);
     }
-  else if (app->app_local->keyattr[keyno].key_type == KEY_TYPE_ECC)
+  else
     {
+      /* ECDSA, ECDH or EdDSA */
       const char *curve_name
         = get_curve_name (app->app_local->keyattr[keyno].ecc.curve);

-      err = gcry_sexp_build (&s_pkey, NULL,
-                             "(public-key(ecc(curve%s)(q%b)))",
-                             curve_name, (int)mlen, mbuf);
-      if (err)
-        goto leave;
-
-      len = gcry_sexp_sprint (s_pkey, GCRYSEXP_FMT_CANON, NULL, 0);
-
-      keybuf = xtrymalloc (len);
-      if (!keybuf)
-        {
-          gcry_sexp_release (s_pkey);
-          err = gpg_error_from_syserror ();
-          goto leave;
-        }
-      gcry_sexp_sprint (s_pkey, GCRYSEXP_FMT_CANON, keybuf, len);
-      gcry_sexp_release (s_pkey);
+      if (app->app_local->keyattr[keyno].ecc.curve == CURVE_ED25519
+          || app->app_local->keyattr[keyno].ecc.curve == CURVE_CURVE25519)
+        err = gcry_sexp_build (&s_pkey, NULL,
+                               "(public-key(ecc(curve%s)(flags eddsa)(q%b)))",
+                               curve_name, (int)mlen, mbuf);
+      else
+        err = gcry_sexp_build (&s_pkey, NULL,
+                               "(public-key(ecc(curve%s)(q%b)))",
+                               curve_name, (int)mlen, mbuf);
     }
-  else if (app->app_local->keyattr[keyno].key_type == KEY_TYPE_EDDSA)
-    {
-      const char *curve_name
-        = get_curve_name (app->app_local->keyattr[keyno].eddsa.curve);

-      err = gcry_sexp_build (&s_pkey, NULL,
-                             "(public-key(ecc(curve%s)(flags eddsa)(q%b)))",
-                             curve_name, (int)mlen, mbuf);
-      if (err)
-        goto leave;
-
-      len = gcry_sexp_sprint (s_pkey, GCRYSEXP_FMT_CANON, NULL, 0);
-
-      keybuf = xtrymalloc (len);
-      if (!keybuf)
-        {
-          gcry_sexp_release (s_pkey);
-          err = gpg_error_from_syserror ();
-          goto leave;
-        }
-      gcry_sexp_sprint (s_pkey, GCRYSEXP_FMT_CANON, keybuf, len);
-      gcry_sexp_release (s_pkey);
-    }
-  else
+  if (err)
+    goto leave;
+  len = gcry_sexp_sprint (s_pkey, GCRYSEXP_FMT_CANON, NULL, 0);
+  keybuf = xtrymalloc (len);
+  if (!keybuf)
     {
-      err = gpg_error (GPG_ERR_NOT_IMPLEMENTED);
+      gcry_sexp_release (s_pkey);
+      err = gpg_error_from_syserror ();
       goto leave;
     }
-
+  gcry_sexp_sprint (s_pkey, GCRYSEXP_FMT_CANON, keybuf, len);
+  gcry_sexp_release (s_pkey);
   app->app_local->pk[keyno].key = (unsigned char*)keybuf;
   app->app_local->pk[keyno].keylen = len - 1; /* Decrement for trailing '\0' */

@@ -3264,6 +3235,8 @@ ecc_writekey (app_t app, gpg_error_t (*pincb)(void*, const char *, char **),
             curve = CURVE_SEC_P256K1;
           else if (tok && toklen == 7 && !memcmp (tok, "Ed25519", 7))
             curve = CURVE_ED25519;
+          else if (tok && toklen == 10 && !memcmp (tok, "Curve25519", 10))
+            curve = CURVE_CURVE25519;
           else
             {
               log_error (_("unsupported curve\n"));
@@ -3289,7 +3262,8 @@ ecc_writekey (app_t app, gpg_error_t (*pincb)(void*, const char *, char **),
             }
           if ((err = parse_sexp (&buf, &buflen, &depth, &tok, &toklen)))
             goto leave;
-          if (tok && buf2 && curve != CURVE_ED25519)
+          if (tok && buf2
+              && curve != CURVE_ED25519 && curve != CURVE_CURVE25519)
             /* It's MPI.  Strip off leading zero bytes and save. */
             for (;toklen && !*tok; toklen--, tok++)
               ;
@@ -3396,10 +3370,13 @@ ecc_writekey (app_t app, gpg_error_t (*pincb)(void*, const char *, char **),
                    curve == CURVE_ED25519 ? KEY_TYPE_EDDSA : KEY_TYPE_ECC,
                    curve == CURVE_ED25519 ?
                    "\x09\x2b\x06\x01\x04\x01\xda\x47\x0f\x01"
+                   : curve == CURVE_CURVE25519 ?
+                   "\x0a\x2b\x06\x01\x04\x01\x97\x55\x01\x05\x01"
                    : curve == CURVE_NIST_P256 ?
                    "\x08\x2a\x86\x48\xce\x3d\x03\x01\x07"
                    : "\x05\x2b\x81\x04\x00\x0a",
                    (size_t)(curve == CURVE_ED25519 ? 10
+                            : curve == CURVE_CURVE25519 ? 11
                             : curve == CURVE_NIST_P256? 9 : 6),
                    ecc_q, ecc_q_len, "\x03\x01\x08\x07", (size_t)4);
   if (err)
@@ -4396,6 +4373,8 @@ parse_ecc_curve (const unsigned char *buffer, size_t buflen)
     curve = CURVE_SEC_P256K1;
   else if (buflen == 9)
     curve = CURVE_ED25519;
+  else if (buflen == 10)
+    curve = CURVE_CURVE25519;
   else
     curve = CURVE_UNKNOWN;

@@ -4470,12 +4449,12 @@ parse_algorithm_attribute (app_t app, int keyno)
   else if (*buffer == 22) /* EdDSA */
     {
       app->app_local->keyattr[keyno].key_type = KEY_TYPE_EDDSA;
-      app->app_local->keyattr[keyno].eddsa.curve
+      app->app_local->keyattr[keyno].ecc.curve
         = parse_ecc_curve (buffer + 1, buflen - 1);
       if (opt.verbose)
         log_printf
           ("EdDSA, curve=%s\n",
-           get_curve_name (app->app_local->keyattr[keyno].eddsa.curve));
+           get_curve_name (app->app_local->keyattr[keyno].ecc.curve));
     }
   else if (opt.verbose)
     log_printhex ("", buffer, buflen);
--



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