commit 3a0df033643261d3872f8176568814a32103c2f8
author Andrzej Kurek <andrzej.kurek@arm.com> Fri Jun 12 06:32:13 2020 -0400
committer Andrzej Kurek <andrzej.kurek@arm.com> Fri Jun 12 06:32:13 2020 -0400
tree f9fe67a560011d961b9cb7c4f35d72c3f2c6d2ba
parent 8f52a8a8c06ba767ce0be2cf8d1406b7b24878a2

Increase the Hamming distance of uECC_generate_random_int returns

Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>

include/tinycrypt/ecc.h

diff --git a/include/tinycrypt/ecc.h b/include/tinycrypt/ecc.h
index b6fbc69..57aa508 100644
--- a/include/tinycrypt/ecc.h
+++ b/include/tinycrypt/ecc.h
@@ -155,7 +155,8 @@
  * @param random OUT -- random integer in the range 0 < random < top
  * @param top IN -- upper limit
  * @param num_words IN -- number of words
- * @return a random integer in the range 0 < random < top
+ * @return UECC_SUCCESS in case of success
+ * @return UECC_FAILURE upon failure
  */
 int uECC_generate_random_int(uECC_word_t *random, const uECC_word_t *top,
 			     wordcount_t num_words);

tinycrypt/ecc.c

diff --git a/tinycrypt/ecc.c b/tinycrypt/ecc.c
index 57b3228..ca91e12 100644
--- a/tinycrypt/ecc.c
+++ b/tinycrypt/ecc.c
@@ -1080,7 +1080,7 @@
 	/* If an RNG function was specified, get a random initial Z value to
          * protect against side-channel attacks such as Template SPA */
 	if (g_rng_function) {
-		if (!uECC_generate_random_int(k2[carry], curve_p, num_words)) {
+		if (uECC_generate_random_int(k2[carry], curve_p, num_words) != UECC_SUCCESS) {
 			r = UECC_FAILURE;
 			goto clear_and_out;
 		}
@@ -1165,21 +1165,21 @@
 	bitcount_t num_bits = uECC_vli_numBits(top);
 
 	if (!g_rng_function) {
-		return 0;
+		return UECC_FAILURE;
 	}
 
 	for (tries = 0; tries < uECC_RNG_MAX_TRIES; ++tries) {
 		if (g_rng_function((uint8_t *)random, num_words * uECC_WORD_SIZE) != num_words * uECC_WORD_SIZE) {
-      			return 0;
+      			return UECC_FAILURE;
     		}
 		random[num_words - 1] &=
         		mask >> ((bitcount_t)(num_words * uECC_WORD_SIZE * 8 - num_bits));
 		if (!uECC_vli_isZero(random) &&
 			uECC_vli_cmp(top, random) == 1) {
-			return 1;
+			return UECC_SUCCESS;
 		}
 	}
-	return 0;
+	return UECC_FAILURE;
 }
 
 

tinycrypt/ecc_dsa.c

diff --git a/tinycrypt/ecc_dsa.c b/tinycrypt/ecc_dsa.c
index 70f9c8b..bb3ed81 100644
--- a/tinycrypt/ecc_dsa.c
+++ b/tinycrypt/ecc_dsa.c
@@ -109,7 +109,7 @@
 		uECC_vli_clear(tmp);
 		tmp[0] = 1;
 	}
-	else if (!uECC_generate_random_int(tmp, curve_n, num_n_words)) {
+	else if (uECC_generate_random_int(tmp, curve_n, num_n_words) != UECC_SUCCESS) {
 		return UECC_FAILURE;
 	}