Hi,

              I am working on a embedded platform, that does not has any entropy source except system ticks. To improve the randomness, I am trying to utilize NV_SEED operations. The version of mbedtls version 2.16.2 is being used.

Configuration file I have enabled:

#define MBEDTLS_ENTROPY_NV_SEED

#define MBEDTLS_PLATFORM_NV_SEED_ALT

After initializing and before seeding random number generator, I assign functions of nv seed read and write to platform seeding function as below.

   if( r = mbedtls_platform_set_nv_seed(FN_NV_SEED_RD, FN_NV_SEED_WR) )

   {

      return( r );

   }

   if( r = mbedtls_ctr_drbg_seed( &CtrDrbg, mbedtls_entropy_func, &Entropy,

                                  (const unsigned char *) u8SeedingString, (size_t)Length ) )

   {

      return ( r );

   }

Later functions to generate random and free context.

While running, I could see only the FN_NV_SEED_RD  function is getting called. And, FN_NV_SEED_WR  function is not getting called. I tried to add some print statements in mbedtls library function, mbedtls_entropy_update_nv_seed().

But it looks like, this function was never called by the library.

1. Anything else to be done?
2. someone could help me ensure NV_SEED is properly incorporated
3. How to trace the issue.

Thanks,

Gopi Krishnan