From 60dca948219c3a5792166c4287f784be05b1c2c9 Mon Sep 17 00:00:00 2001
From: kaleb-himes <kaleb@wolfssl.com>
Date: Wed, 20 Sep 2017 10:36:36 -0600
Subject: [PATCH 1/2] Update HASH_DRBG Reseed mechanism and add test case

---
 tests/api.c                | 29 +++++++++++++++++++++++++++++
 wolfcrypt/src/random.c     |  5 ++++-
 wolfssl/wolfcrypt/random.h |  1 +
 3 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/tests/api.c b/tests/api.c
index cf3b49baa..ab110ed65 100644
--- a/tests/api.c
+++ b/tests/api.c
@@ -10533,6 +10533,30 @@ static int test_tls13_apis(void)
 
 #endif
 
+#ifdef HAVE_HASHDRBG
+
+static int test_wc_RNG_GenerateBlock()
+{
+    int i, ret;
+    WC_RNG rng;
+    byte key[32];
+
+    ret = wc_InitRng(&rng);
+
+    if (ret == 0) {
+        for(i = 0; i < WC_RESEED_INTERVAL + 10; i++) {
+            ret = wc_RNG_GenerateBlock(&rng, key, sizeof(key));
+            if (ret != 0) {
+                break;
+            }
+        }
+    }
+
+    wc_FreeRng(&rng);
+
+    return ret;
+}
+#endif
 
 /*----------------------------------------------------------------------------*
  | Main
@@ -10716,6 +10740,11 @@ void ApiTest(void)
     AssertIntEQ(test_wc_DsaPublicPrivateKeyDecode(), 0);
     AssertIntEQ(test_wc_MakeDsaKey(), 0);
     AssertIntEQ(test_wc_DsaKeyToDer(), 0);
+
+#ifdef HAVE_HASHDRBG
+    AssertIntEQ(WC_RESEED_INTERVAL, 1000000);
+    AssertIntEQ(test_wc_RNG_GenerateBlock(), 0);
+#endif
     printf(" End API Tests\n");
 
 }
diff --git a/wolfcrypt/src/random.c b/wolfcrypt/src/random.c
index 5df65091c..6d20d96ab 100644
--- a/wolfcrypt/src/random.c
+++ b/wolfcrypt/src/random.c
@@ -154,7 +154,7 @@ int wc_RNG_GenerateByte(WC_RNG* rng, byte* b)
 
 #define OUTPUT_BLOCK_LEN  (SHA256_DIGEST_SIZE)
 #define MAX_REQUEST_LEN   (0x10000)
-#define RESEED_INTERVAL   (1000000)
+#define RESEED_INTERVAL   WC_RESEED_INTERVAL
 #define SECURITY_STRENGTH (256)
 #define ENTROPY_SZ        (SECURITY_STRENGTH/8)
 #define NONCE_SZ          (ENTROPY_SZ/2)
@@ -449,6 +449,9 @@ static int Hash_DRBG_Generate(DRBG* drbg, byte* out, word32 outSz)
 
     FREE_VAR(digest, drbg->heap);
 
+    if (ret == DRBG_NEED_RESEED)
+        return ret;
+
     return (ret == 0) ? DRBG_SUCCESS : DRBG_FAILURE;
 }
 
diff --git a/wolfssl/wolfcrypt/random.h b/wolfssl/wolfcrypt/random.h
index 1e72eb16e..b012c6bf8 100644
--- a/wolfssl/wolfcrypt/random.h
+++ b/wolfssl/wolfcrypt/random.h
@@ -60,6 +60,7 @@
 #if !defined(WC_NO_HASHDRBG) || !defined(CUSTOM_RAND_GENERATE_BLOCK)
     #undef  HAVE_HASHDRBG
     #define HAVE_HASHDRBG
+    #define WC_RESEED_INTERVAL (1000000)
 #endif
 
 

From 5777b927458bb7dbf6276fabfe90e22f364696e7 Mon Sep 17 00:00:00 2001
From: kaleb-himes <kaleb@wolfssl.com>
Date: Wed, 20 Sep 2017 11:25:51 -0600
Subject: [PATCH 2/2] Improved solution

---
 tests/api.c                |  1 -
 wolfcrypt/src/random.c     | 22 +++++++++++-----------
 wolfssl/wolfcrypt/random.h |  4 +++-
 3 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/tests/api.c b/tests/api.c
index ab110ed65..93e53f84e 100644
--- a/tests/api.c
+++ b/tests/api.c
@@ -10742,7 +10742,6 @@ void ApiTest(void)
     AssertIntEQ(test_wc_DsaKeyToDer(), 0);
 
 #ifdef HAVE_HASHDRBG
-    AssertIntEQ(WC_RESEED_INTERVAL, 1000000);
     AssertIntEQ(test_wc_RNG_GenerateBlock(), 0);
 #endif
     printf(" End API Tests\n");
diff --git a/wolfcrypt/src/random.c b/wolfcrypt/src/random.c
index 6d20d96ab..3a000e132 100644
--- a/wolfcrypt/src/random.c
+++ b/wolfcrypt/src/random.c
@@ -408,13 +408,17 @@ static INLINE void array_add(byte* d, word32 dLen, const byte* s, word32 sLen)
 /* Returns: DRBG_SUCCESS, DRBG_NEED_RESEED, or DRBG_FAILURE */
 static int Hash_DRBG_Generate(DRBG* drbg, byte* out, word32 outSz)
 {
-    int ret = DRBG_NEED_RESEED;
+    int ret;
     Sha256 sha;
-    DECLARE_VAR(digest, byte, SHA256_DIGEST_SIZE, drbg->heap);
+    byte type;
+    word32 reseedCtr;
 
-    if (drbg->reseedCtr != RESEED_INTERVAL) {
-        byte type = drbgGenerateH;
-        word32 reseedCtr = drbg->reseedCtr;
+    if (drbg->reseedCtr == RESEED_INTERVAL) {
+        return DRBG_NEED_RESEED;
+    } else {
+        DECLARE_VAR(digest, byte, SHA256_DIGEST_SIZE, drbg->heap);
+        type = drbgGenerateH;
+        reseedCtr = drbg->reseedCtr;
 
         ret = Hash_gen(drbg, out, outSz, drbg->V);
         if (ret == DRBG_SUCCESS) {
@@ -444,13 +448,9 @@ static int Hash_DRBG_Generate(DRBG* drbg, byte* out, word32 outSz)
             }
             drbg->reseedCtr++;
         }
+        ForceZero(digest, SHA256_DIGEST_SIZE);
+        FREE_VAR(digest, drbg->heap);
     }
-    ForceZero(digest, SHA256_DIGEST_SIZE);
-
-    FREE_VAR(digest, drbg->heap);
-
-    if (ret == DRBG_NEED_RESEED)
-        return ret;
 
     return (ret == 0) ? DRBG_SUCCESS : DRBG_FAILURE;
 }
diff --git a/wolfssl/wolfcrypt/random.h b/wolfssl/wolfcrypt/random.h
index b012c6bf8..13afbafb5 100644
--- a/wolfssl/wolfcrypt/random.h
+++ b/wolfssl/wolfcrypt/random.h
@@ -60,7 +60,9 @@
 #if !defined(WC_NO_HASHDRBG) || !defined(CUSTOM_RAND_GENERATE_BLOCK)
     #undef  HAVE_HASHDRBG
     #define HAVE_HASHDRBG
-    #define WC_RESEED_INTERVAL (1000000)
+    #ifndef WC_RESEED_INTERVAL
+        #define WC_RESEED_INTERVAL (1000000)
+    #endif
 #endif