From 05beb9ac7073551cfc06dc6daf2c4473e26ffab3 Mon Sep 17 00:00:00 2001
From: Shelly Liberman <shelly.liberman@arm.com>
Date: Sun, 13 Sep 2020 15:23:56 +0300
Subject: [PATCH] replace user rand by platform rand in ecc delays

Signed-off-by: Shelly Liberman <shelly.liberman@arm.com>
---
 include/mbedtls/platform_util.h |  9 +++++++++
 library/platform_util.c         | 19 +++++++++++++++++++
 tinycrypt/ecc.c                 |  3 ++-
 3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/include/mbedtls/platform_util.h b/include/mbedtls/platform_util.h
index 68b488716..b44be2317 100644
--- a/include/mbedtls/platform_util.h
+++ b/include/mbedtls/platform_util.h
@@ -300,6 +300,15 @@ uint32_t mbedtls_platform_random_in_range( uint32_t num );
  */
 void mbedtls_platform_random_delay( void );
 
+/**
+ * \brief       RNG-function for getting a random buffer.
+ *
+ * \param buf   Buffer for random data
+ * \param len   Length of the buffer in bytes
+ *
+ */
+void mbedtls_platform_random_buf( uint8_t *buf, size_t len);
+
 #if defined(MBEDTLS_HAVE_TIME_DATE)
 /**
  * \brief      Platform-specific implementation of gmtime_r()
diff --git a/library/platform_util.c b/library/platform_util.c
index d62039618..458dfc9be 100644
--- a/library/platform_util.c
+++ b/library/platform_util.c
@@ -319,6 +319,25 @@ uint32_t mbedtls_platform_random_uint32( void )
               mbedtls_platform_random_uint16() );
 }
 
+void mbedtls_platform_random_buf( uint8_t *buf, size_t len )
+{
+    uint16_t val;
+
+    while( len > 1 )
+    {
+        val = mbedtls_platform_random_uint16();
+        buf[len-1] = (uint8_t)val;
+        buf[len-2] = (uint8_t)(val>>8);
+        len -= 2;
+    }
+    if( len == 1 )
+    {
+        buf[0] = (uint8_t)mbedtls_platform_random_uint16();
+    }
+
+    return;
+}
+
 uint32_t mbedtls_platform_random_in_range( uint32_t num )
 {
     uint32_t result;
diff --git a/tinycrypt/ecc.c b/tinycrypt/ecc.c
index bf54fe8e7..aeb6447f3 100644
--- a/tinycrypt/ecc.c
+++ b/tinycrypt/ecc.c
@@ -67,6 +67,7 @@
 #include "mbedtls/platform_util.h"
 #include "mbedtls/sha256.h"
 #include <string.h>
+#include "mbedtls/platform_util.h"
 
 /* Parameters for curve NIST P-256 aka secp256r1 */
 const uECC_word_t curve_p[NUM_ECC_WORDS] = {
@@ -427,7 +428,7 @@ void ecc_wait_state_reset(ecc_wait_state_t *ws)
 		return;
 
 	ws->i = 0;
-	g_rng_function(ws->delays, sizeof(ws->delays));
+	mbedtls_platform_random_buf(ws->delays, sizeof(ws->delays));
 }
 
 /* Computes result = left * right. Result must be 2 * num_words long.