Move ECDH functionality to a new file

1 files changed, 60 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..f649b652b6
--- /dev/null
+++ b/lib/crypto/c_src/ecdh.c
@@ -0,0 +1,60 @@
+#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 field_size = 0;
+    int i;
+    EC_GROUP *group;
+    const BIGNUM *priv_key;
+    EC_POINT *my_ecpoint = NULL;
+    EC_KEY *other_ecdh = NULL;
+
+    if (!get_ec_key(env, argv[1], argv[2], atom_undefined, &key))
+	return make_badarg_maybe(env);
+
+    group    = EC_GROUP_dup(EC_KEY_get0_group(key));
+    priv_key = EC_KEY_get0_private_key(key);
+
+    if (!term2point(env, argv[0], group, &my_ecpoint)) {
+	goto out_err;
+    }
+
+    if ((other_ecdh = EC_KEY_new()) == NULL
+	|| !EC_KEY_set_group(other_ecdh, group)
+	|| !EC_KEY_set_private_key(other_ecdh, priv_key))
+	goto out_err;
+
+    field_size = EC_GROUP_get_degree(group);
+    if (field_size <= 0)
+	goto out_err;
+
+    p = enif_make_new_binary(env, (field_size+7)/8, &ret);
+    i = ECDH_compute_key(p, (field_size+7)/8, my_ecpoint, other_ecdh, NULL);
+
+    if (i < 0)
+	    goto out_err;
+out:
+    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;
+
+out_err:
+    ret = enif_make_badarg(env);
+    goto out;
+#else
+    return atom_notsup;
+#endif
+}