1 files changed, 94 insertions, 0 deletions
diff --git a/lib/crypto/c_src/ecdh.c b/lib/crypto/c_src/ecdh.c
new file mode 100644
index 0000000000..9e3f460519
--- /dev/null
+++ b/lib/crypto/c_src/ecdh.c
@@ -0,0 +1,94 @@
+/*
+ * %CopyrightBegin%
+ *
+ * Copyright Ericsson AB 2010-2018. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * %CopyrightEnd%
+ */
+
+#include "ecdh.h"
+#include "ec.h"
+
+/*
+  (_OthersPublicKey, _MyPrivateKey)
+  (_OthersPublicKey, _MyEC_Point)
+*/
+ERL_NIF_TERM ecdh_compute_key_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+/* (OtherPublicKey, Curve, My) */
+{
+#if defined(HAVE_EC)
+    ERL_NIF_TERM ret;
+    unsigned char *p;
+    EC_KEY* key = NULL;
+    int degree;
+    size_t field_size;
+    EC_GROUP *group = NULL;
+    const BIGNUM *priv_key;
+    EC_POINT *my_ecpoint = NULL;
+    EC_KEY *other_ecdh = NULL;
+
+    ASSERT(argc == 3);
+
+    if (!get_ec_key(env, argv[1], argv[2], atom_undefined, &key))
+        goto bad_arg;
+    if ((group = EC_GROUP_dup(EC_KEY_get0_group(key))) == NULL)
+        goto bad_arg;
+    priv_key = EC_KEY_get0_private_key(key);
+
+    if (!term2point(env, argv[0], group, &my_ecpoint)) {
+        goto err;
+    }
+
+    if ((other_ecdh = EC_KEY_new()) == NULL)
+        goto err;
+    if (!EC_KEY_set_group(other_ecdh, group))
+        goto err;
+    if (!EC_KEY_set_private_key(other_ecdh, priv_key))
+        goto err;
+
+    if ((degree = EC_GROUP_get_degree(group)) <= 0)
+        goto err;
+
+    field_size = (size_t)degree;
+    if ((p = enif_make_new_binary(env, (field_size+7)/8, &ret)) == NULL)
+        goto err;
+    if (ECDH_compute_key(p, (field_size+7)/8, my_ecpoint, other_ecdh, NULL) < 1)
+        goto err;
+
+    goto done;
+
+ bad_arg:
+    ret = make_badarg_maybe(env);
+    goto done;
+
+ err:
+    ret = enif_make_badarg(env);
+
+ done:
+    if (group)
+        EC_GROUP_free(group);
+    if (my_ecpoint)
+        EC_POINT_free(my_ecpoint);
+    if (other_ecdh)
+        EC_KEY_free(other_ecdh);
+    if (key)
+        EC_KEY_free(key);
+
+    return ret;
+
+#else
+    return atom_notsup;
+#endif
+}