Add micro-ecc based ecc-files to mbedtls

The files are from https://github.com/intel/tinycrypt
Using commit 6e0eb53fc8403988f97345e94081b0453f47231d as a base.
diff --git a/tinycrypt/ecc_dh.c b/tinycrypt/ecc_dh.c
new file mode 100644
index 0000000..e5257d2
--- /dev/null
+++ b/tinycrypt/ecc_dh.c
@@ -0,0 +1,200 @@
+/* ec_dh.c - TinyCrypt implementation of EC-DH */
+
+/* 
+ * Copyright (c) 2014, Kenneth MacKay
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ *  Copyright (C) 2017 by Intel Corporation, All Rights Reserved.
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions are met:
+ *
+ *    - Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *
+ *    - Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ *    - Neither the name of Intel Corporation nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ *  POSSIBILITY OF SUCH DAMAGE.
+ */
+#include <tinycrypt/constants.h>
+#include <tinycrypt/ecc.h>
+#include <tinycrypt/ecc_dh.h>
+#include <string.h>
+
+#if default_RNG_defined
+static uECC_RNG_Function g_rng_function = &default_CSPRNG;
+#else
+static uECC_RNG_Function g_rng_function = 0;
+#endif
+
+int uECC_make_key_with_d(uint8_t *public_key, uint8_t *private_key,
+			 unsigned int *d, uECC_Curve curve)
+{
+
+	uECC_word_t _private[NUM_ECC_WORDS];
+	uECC_word_t _public[NUM_ECC_WORDS * 2];
+
+	/* This function is designed for test purposes-only (such as validating NIST
+	 * test vectors) as it uses a provided value for d instead of generating
+	 * it uniformly at random. */
+	memcpy (_private, d, NUM_ECC_BYTES);
+
+	/* Computing public-key from private: */
+	if (EccPoint_compute_public_key(_public, _private, curve)) {
+
+		/* Converting buffers to correct bit order: */
+		uECC_vli_nativeToBytes(private_key,
+				       BITS_TO_BYTES(curve->num_n_bits),
+				       _private);
+		uECC_vli_nativeToBytes(public_key,
+				       curve->num_bytes,
+				       _public);
+		uECC_vli_nativeToBytes(public_key + curve->num_bytes,
+				       curve->num_bytes,
+				       _public + curve->num_words);
+
+		/* erasing temporary buffer used to store secret: */
+		memset(_private, 0, NUM_ECC_BYTES);
+
+		return 1;
+	}
+	return 0;
+}
+
+int uECC_make_key(uint8_t *public_key, uint8_t *private_key, uECC_Curve curve)
+{
+
+	uECC_word_t _random[NUM_ECC_WORDS * 2];
+	uECC_word_t _private[NUM_ECC_WORDS];
+	uECC_word_t _public[NUM_ECC_WORDS * 2];
+	uECC_word_t tries;
+
+	for (tries = 0; tries < uECC_RNG_MAX_TRIES; ++tries) {
+		/* Generating _private uniformly at random: */
+		uECC_RNG_Function rng_function = uECC_get_rng();
+		if (!rng_function ||
+			!rng_function((uint8_t *)_random, 2 * NUM_ECC_WORDS*uECC_WORD_SIZE)) {
+        		return 0;
+		}
+
+		/* computing modular reduction of _random (see FIPS 186.4 B.4.1): */
+		uECC_vli_mmod(_private, _random, curve->n, BITS_TO_WORDS(curve->num_n_bits));
+
+		/* Computing public-key from private: */
+		if (EccPoint_compute_public_key(_public, _private, curve)) {
+
+			/* Converting buffers to correct bit order: */
+			uECC_vli_nativeToBytes(private_key,
+					       BITS_TO_BYTES(curve->num_n_bits),
+					       _private);
+			uECC_vli_nativeToBytes(public_key,
+					       curve->num_bytes,
+					       _public);
+			uECC_vli_nativeToBytes(public_key + curve->num_bytes,
+ 					       curve->num_bytes,
+					       _public + curve->num_words);
+
+			/* erasing temporary buffer that stored secret: */
+			memset(_private, 0, NUM_ECC_BYTES);
+
+      			return 1;
+    		}
+  	}
+	return 0;
+}
+
+int uECC_shared_secret(const uint8_t *public_key, const uint8_t *private_key,
+		       uint8_t *secret, uECC_Curve curve)
+{
+
+	uECC_word_t _public[NUM_ECC_WORDS * 2];
+	uECC_word_t _private[NUM_ECC_WORDS];
+
+	uECC_word_t tmp[NUM_ECC_WORDS];
+	uECC_word_t *p2[2] = {_private, tmp};
+	uECC_word_t *initial_Z = 0;
+	uECC_word_t carry;
+	wordcount_t num_words = curve->num_words;
+	wordcount_t num_bytes = curve->num_bytes;
+	int r;
+
+	/* Converting buffers to correct bit order: */
+	uECC_vli_bytesToNative(_private,
+      			       private_key,
+			       BITS_TO_BYTES(curve->num_n_bits));
+	uECC_vli_bytesToNative(_public,
+      			       public_key,
+			       num_bytes);
+	uECC_vli_bytesToNative(_public + num_words,
+			       public_key + num_bytes,
+			       num_bytes);
+
+	/* Regularize the bitcount for the private key so that attackers cannot use a
+	 * side channel attack to learn the number of leading zeros. */
+	carry = regularize_k(_private, _private, tmp, curve);
+
+	/* If an RNG function was specified, try to get a random initial Z value to
+	 * improve protection against side-channel attacks. */
+	if (g_rng_function) {
+		if (!uECC_generate_random_int(p2[carry], curve->p, num_words)) {
+			r = 0;
+			goto clear_and_out;
+    		}
+    		initial_Z = p2[carry];
+  	}
+
+	EccPoint_mult(_public, _public, p2[!carry], initial_Z, curve->num_n_bits + 1,
+		      curve);
+
+	uECC_vli_nativeToBytes(secret, num_bytes, _public);
+	r = !EccPoint_isZero(_public, curve);
+
+clear_and_out:
+	/* erasing temporary buffer used to store secret: */
+	memset(p2, 0, sizeof(p2));
+	__asm__ __volatile__("" :: "g"(p2) : "memory");
+	memset(tmp, 0, sizeof(tmp));
+	__asm__ __volatile__("" :: "g"(tmp) : "memory");
+	memset(_private, 0, sizeof(_private));
+	__asm__ __volatile__("" :: "g"(_private) : "memory");
+
+	return r;
+}