Add random delay to enforce_volatile_reads
Add a random delay to mbedtls_platform_enforce_volatile_reads() as a
countermeasure to fault injection attacks.
diff --git a/include/mbedtls/platform_util.h b/include/mbedtls/platform_util.h
index 96c96a3..3bad559 100644
--- a/include/mbedtls/platform_util.h
+++ b/include/mbedtls/platform_util.h
@@ -260,9 +260,12 @@
int mbedtls_platform_random_delay( size_t num );
/**
- * \brief This function does nothing, but can be inserted between
- * successive reads to a volatile local variable to prevent
- * compilers from optimizing them away.
+ * \brief This function can be inserted between successive reads to a
+ * volatile local variable to prevent compilers from optimizing
+ * them away. In addition, this function will spent a small random
+ * time in a busy loop as a counter-measure to fault injection
+ * attack.
+ *
*/
void mbedtls_platform_enforce_volatile_reads( void );