crypto: selective support for GF2m curves

Newer OpenSSL versions allow to selectively disable GF2m elliptic curves.
Selectively enable GF2m curves is support for them is available.

3 files changed, 34 insertions, 10 deletions

diff --git a/lib/crypto/c_src/crypto.c b/lib/crypto/c_src/crypto.c
index 49b6f9cc55..925ad0c091 100644
--- a/lib/crypto/c_src/crypto.c
+++ b/lib/crypto/c_src/crypto.c
@@ -625,7 +625,7 @@ static void unload(ErlNifEnv* env, void* priv_data)
 static int algo_hash_cnt;
 static ERL_NIF_TERM algo_hash[8];   /* increase when extending the list */
 static int algo_pubkey_cnt;
-static ERL_NIF_TERM algo_pubkey[2]; /* increase when extending the list */
+static ERL_NIF_TERM algo_pubkey[3]; /* increase when extending the list */
 static int algo_cipher_cnt;
 static ERL_NIF_TERM algo_cipher[2]; /* increase when extending the list */
 
@@ -651,6 +651,9 @@ static void init_algorithms_types(ErlNifEnv* env)
 
     algo_pubkey_cnt = 0;
 #if defined(HAVE_EC)
+#if !defined(OPENSSL_NO_EC2M)
+    algo_pubkey[algo_pubkey_cnt++] = enif_make_atom(env,"ec_gf2m");
+#endif
     algo_pubkey[algo_pubkey_cnt++] = enif_make_atom(env,"ecdsa");
     algo_pubkey[algo_pubkey_cnt++] = enif_make_atom(env,"ecdh");
 #endif
@@ -2915,6 +2918,8 @@ static EC_KEY* ec_key_new(ErlNifEnv* env, ERL_NIF_TERM curve_arg)
 	    /* create the EC_GROUP structure */
 	    group = EC_GROUP_new_curve_GFp(p, a, b, NULL);
 
+#if !defined(OPENSSL_NO_EC2M)
+
 	} else if (f_arity == 3 && field[0] == atom_characteristic_two_field) {
 	    /* {characteristic_two_field, M, Basis} */
 
@@ -2973,6 +2978,7 @@ static EC_KEY* ec_key_new(ErlNifEnv* env, ERL_NIF_TERM curve_arg)
 		goto out_err;
 
 	    group = EC_GROUP_new_curve_GF2m(p, a, b, NULL);
+#endif
 	} else
 	    goto out_err;
 
diff --git a/lib/crypto/doc/src/crypto.xml b/lib/crypto/doc/src/crypto.xml
index 42c733d243..aa60bba96a 100644
--- a/lib/crypto/doc/src/crypto.xml
+++ b/lib/crypto/doc/src/crypto.xml
@@ -120,7 +120,11 @@
       brainpoolP160r1| brainpoolP160t1| brainpoolP192r1| brainpoolP192t1| brainpoolP224r1|
       brainpoolP224t1| brainpoolP256r1| brainpoolP256t1| brainpoolP320r1| brainpoolP320t1|
       brainpoolP384r1| brainpoolP384t1| brainpoolP512r1| brainpoolP512t1
-    </code></p>
+    </code>
+    Note that the <em>sect</em> curves are GF2m (characteristic two) curves and are only supported if the
+    underlying OpenSSL has support for them.
+    See also <seealso marker="#supports-0">crypto:supports/0</seealso>
+    </p>
 
      <p><code>stream_cipher() = rc4 | aes_ctr </code></p>
 
@@ -149,8 +153,11 @@
      </p>
      <p><code> cipher_algorithms() = des_cbc | des_cfb |  des3_cbc | des3_cbf | des_ede3 |
      blowfish_cbc | blowfish_cfb64 | aes_cbc128 | aes_cfb128| aes_cbc256 | aes_ige256 | rc2_cbc | aes_ctr| rc4  </code> </p>
-     <p><code> public_key_algorithms() =   rsa |dss | ecdsa | dh | ecdh </code> </p>
-     
+     <p><code> public_key_algorithms() =   rsa |dss | ecdsa | dh | ecdh | ec_gf2m</code>
+     Note that ec_gf2m is not strictly a public key algorithm, but a restriction on what curves are supported
+     with ecdsa and ecdh.
+     </p>
+
  </section>
 
   <funcs>
diff --git a/lib/crypto/src/crypto_ec_curves.erl b/lib/crypto/src/crypto_ec_curves.erl
index 8bd1f21edd..fe17643d96 100644
--- a/lib/crypto/src/crypto_ec_curves.erl
+++ b/lib/crypto/src/crypto_ec_curves.erl
@@ -3,19 +3,30 @@
 -export([curve/1, curves/0]).
 
 curves() ->
+    CryptoSupport = crypto:supports(),
+    HasGF2m = proplists:get_bool(ec_gf2m,  proplists:get_value(public_keys, CryptoSupport)),
+    prime_curves() ++ characteristic_two_curves(HasGF2m).
+
+
+prime_curves() ->
     [secp112r1,secp112r2,secp128r1,secp128r2,secp160k1,secp160r1,secp160r2,
      secp192r1,secp192k1,secp224k1,secp224r1,secp256k1,secp256r1,secp384r1,
      secp521r1,prime192v1,prime192v2,prime192v3,prime239v1,prime239v2,prime239v3,
-     prime256v1,sect113r1,sect113r2,sect131r1,sect131r2,sect163k1,sect163r1,
+     prime256v1,wtls6,wtls7,wtls8,wtls9,wtls12,
+     brainpoolP160r1,brainpoolP160t1,brainpoolP192r1,brainpoolP192t1,
+     brainpoolP224r1,brainpoolP224t1,brainpoolP256r1,brainpoolP256t1,
+     brainpoolP320r1,brainpoolP320t1,brainpoolP384r1,brainpoolP384t1,
+     brainpoolP512r1,brainpoolP512t1].
+
+characteristic_two_curves(true) ->
+    [sect113r1,sect113r2,sect131r1,sect131r2,sect163k1,sect163r1,
      sect163r2,sect193r1,sect193r2,sect233k1,sect233r1,sect239k1,sect283k1,
      sect283r1,sect409k1,sect409r1,sect571k1,sect571r1,c2pnb163v1,c2pnb163v2,
      c2pnb163v3,c2pnb176v1,c2tnb191v1,c2tnb191v2,c2tnb191v3,c2pnb208w1,c2tnb239v1,
      c2tnb239v2,c2tnb239v3,c2pnb272w1,c2pnb304w1,c2tnb359v1,c2pnb368w1,c2tnb431r1,
-     wtls1,wtls3,wtls4,wtls5,wtls6,wtls7,wtls8,wtls9,wtls10,wtls11,wtls12,ipsec3,
-     ipsec4,brainpoolP160r1,brainpoolP160t1,brainpoolP192r1,brainpoolP192t1,
-     brainpoolP224r1,brainpoolP224t1,brainpoolP256r1,brainpoolP256t1,
-     brainpoolP320r1,brainpoolP320t1,brainpoolP384r1,brainpoolP384t1,
-     brainpoolP512r1,brainpoolP512t1].
+     wtls1,wtls3,wtls4,wtls5,wtls10,wtls11,ipsec3,ipsec4];
+characteristic_two_curves(_) ->
+    [].
 
 curve(secp112r1) ->
     {