[IOT-1619, IOT-1620] DRBG prediction resistance and init

Enable prediction resistance in the mbedtls DRBG.
Use a static personalization string when initializing the DRBG on all
platforms.

Change-Id: I49f14e395d4ce4e17d832aa9c94717dda066c45e
Signed-off-by: Greg Zaverucha <gregz@microsoft.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/15171Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Randeep Singh <randeep.s@samsung.com>
Reviewed-by: Kevin Kane <kkane@microsoft.com>
Bug: https://jira.iotivity.org/browse/IOT-1684Signed-off-by: Philippe Coval <philippe.coval@osg.samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/15857Reviewed-by: Dmitriy Zhuravlev <d.zhuravlev@samsung.com>
Reviewed-by: George Nash <george.nash@intel.com>
Reviewed-by: Chul Lee <chuls.lee@samsung.com>
Reviewed-by: Nivedita Singhvi <niveditasinghvi@gmail.com>

resource/csdk/connectivity/src/adapter_util/ca_adapter_net_ssl.c

@@ -69,11 +69,11 @@
  * @brief mbedTLS version string length
  */
 #define MBED_TLS_VERSION_LEN (16)
-/**
- * @def SEED
- * @brief Seed for initialization RNG
+ /**
+ * @def PERSONALIZATION_STRING
+ * @brief Personalization string for the mbedtls RNG
  */
-#define SEED "IOTIVITY_RND"
+#define PERSONALIZATION_STRING "IOTIVITY_RND"
 /**
  * @def UUID_PREFIX
  * @brief uuid prefix in certificate subject field
@@ -1378,39 +1378,16 @@ CAResult_t CAinitSslAdapter()
     mbedtls_entropy_init(&g_caSslContext->entropy);
     mbedtls_ctr_drbg_init(&g_caSslContext->rnd);
 
-#ifdef __unix__
-    unsigned char seed[sizeof(SEED)] = {0};
-    int urandomFd = -2;
-    urandomFd = open("/dev/urandom", O_RDONLY);
-    if(urandomFd == -1)
-    {
-        OIC_LOG(ERROR, NET_SSL_TAG, "Fails open /dev/urandom!");
-        oc_mutex_unlock(g_sslContextMutex);
-        CAdeinitSslAdapter();
-        return CA_STATUS_FAILED;
-    }
-    if(0 > read(urandomFd, seed, sizeof(seed)))
-    {
-        OIC_LOG(ERROR, NET_SSL_TAG, "Fails read from /dev/urandom!");
-        close(urandomFd);
-        oc_mutex_unlock(g_sslContextMutex);
-        CAdeinitSslAdapter();
-        return CA_STATUS_FAILED;
-    }
-    close(urandomFd);
-
-#else
-    unsigned char * seed = (unsigned char*) SEED;
-#endif
     if(0 != mbedtls_ctr_drbg_seed(&g_caSslContext->rnd, mbedtls_entropy_func,
-                                  &g_caSslContext->entropy, seed, sizeof(SEED)))
+                                  &g_caSslContext->entropy, 
+                                  (const unsigned char*) PERSONALIZATION_STRING, sizeof(PERSONALIZATION_STRING)))
     {
         OIC_LOG(ERROR, NET_SSL_TAG, "Seed initialization failed!");
         oc_mutex_unlock(g_sslContextMutex);
         CAdeinitSslAdapter();
         return CA_STATUS_FAILED;
     }
-    mbedtls_ctr_drbg_set_prediction_resistance(&g_caSslContext->rnd, MBEDTLS_CTR_DRBG_PR_OFF);
+    mbedtls_ctr_drbg_set_prediction_resistance(&g_caSslContext->rnd, MBEDTLS_CTR_DRBG_PR_ON);
 
 #ifdef __WITH_TLS__
     if (0 != InitConfig(&g_caSslContext->clientTlsConf,

resource/csdk/security/provisioning/src/cloud/csr.c

@@ -62,11 +62,10 @@ static OCByteString g_privateKey = {0, 0};
 #define MAX_STRING_LEN 254
 
 /**
- * @def SEED
- * @brief Seed for initialization RNG
+ * @def PERSONALIZATION_STRING
+ * @brief Personalization string for the mbedtls RNG
  */
-
-#define SEED "IOTIVITY_RND"
+#define PERSONALIZATION_STRING "IOTIVITY_RND"
 
 typedef struct
 {
@@ -111,40 +110,17 @@ static int ecdsaGenKeypair(mbedtls_pk_context * pk)
 
     VERIFY_NON_NULL_RET(pk, TAG, "Param pk is NULL", -1);
 
-    // Entropy seeding
-#ifdef __unix__
-    unsigned char seed[sizeof(SEED)] = {0};
-    int urandomFd = -2;
-    urandomFd = open("/dev/urandom", O_RDONLY);
-    if(urandomFd == -1)
-    {
-        OIC_LOG(ERROR, TAG, "Fails open /dev/urandom!");
-        OIC_LOG_V(DEBUG, TAG, "Out %s", __func__);
-        return -1;
-    }
-    if(0 > read(urandomFd, seed, sizeof(seed)))
-    {
-        OIC_LOG(ERROR, TAG, "Fails read from /dev/urandom!");
-        close(urandomFd);
-        OIC_LOG_V(DEBUG, TAG, "Out %s", __func__);
-        return -1;
-    }
-    close(urandomFd);
-
-#else
-    unsigned char * seed = (unsigned char*) SEED;
-#endif
-    // Initialize and seed DRBG context
+    // Initialize the DRBG context
     mbedtls_ctr_drbg_init(&ctr_drbg);
     mbedtls_entropy_init(&entropy);
     if (0 != mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func,
-                                   &entropy, seed, sizeof(SEED)))
+                                   &entropy, PERSONALIZATION_STRING, sizeof(PERSONALIZATION_STRING)))
     {
         OIC_LOG(ERROR, TAG, "Seed initialization failed!");
         OIC_LOG_V(DEBUG, TAG, "Out %s", __func__);
         return -1;
     }
-    mbedtls_ctr_drbg_set_prediction_resistance(&ctr_drbg, MBEDTLS_CTR_DRBG_PR_OFF);
+    mbedtls_ctr_drbg_set_prediction_resistance(&ctr_drbg, MBEDTLS_CTR_DRBG_PR_ON);
     // Initialize l context
     mbedtls_pk_init(pk);
     if (0 > mbedtls_pk_setup(pk, mbedtls_pk_info_from_type(MBEDTLS_PK_ECKEY)))
@@ -232,40 +208,17 @@ static int GenerateCSR(char *subject, OCByteString *csr)
         return -1;
     }
 
-    // Entropy seeding
-#ifdef __unix__
-    unsigned char seed[sizeof(SEED)] = {0};
-    int urandomFd = -2;
-    urandomFd = open("/dev/urandom", O_RDONLY);
-    if(urandomFd == -1)
-    {
-        OIC_LOG(ERROR, TAG, "Fails open /dev/urandom!");
-        OIC_LOG_V(DEBUG, TAG, "Out %s", __func__);
-        return -1;
-    }
-    if(0 > read(urandomFd, seed, sizeof(seed)))
-    {
-        OIC_LOG(ERROR, TAG, "Fails read from /dev/urandom!");
-        close(urandomFd);
-        OIC_LOG_V(DEBUG, TAG, "Out %s", __func__);
-        return -1;
-    }
-    close(urandomFd);
-
-#else
-    unsigned char * seed = (unsigned char *) SEED;
-#endif
-    // Initialize and seed DRBG context
+    // Initialize the DRBG context
     mbedtls_ctr_drbg_init(&ctr_drbg);
     mbedtls_entropy_init(&entropy);
     if (0 != mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func,
-                                   &entropy, seed, sizeof(SEED)))
+                                   &entropy, PERSONALIZATION_STRING, sizeof(PERSONALIZATION_STRING)))
     {
         OIC_LOG(ERROR, TAG, "Seed initialization failed!");
         OIC_LOG_V(DEBUG, TAG, "Out %s", __func__);
         return -1;
     }
-    mbedtls_ctr_drbg_set_prediction_resistance(&ctr_drbg, MBEDTLS_CTR_DRBG_PR_OFF);
+    mbedtls_ctr_drbg_set_prediction_resistance(&ctr_drbg, MBEDTLS_CTR_DRBG_PR_ON);
 
     // Create CSR
     buf = (unsigned char *)OICMalloc(bufsize * sizeof(unsigned char));