From: Dr. Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
Date: Mon, 9 Oct 2017 21:51:42 +0000 (+0200)
Subject: Remove unnecessary DRBG_RESEED state
X-Git-Tag: OpenSSL_1_1_1-pre1~532
X-Git-Url: https://git.openssl.org/?p=openssl.git;a=commitdiff_plain;h=e0b625f9db00509af9004b7907d44b78f332754a

Remove unnecessary DRBG_RESEED state

The DRBG_RESEED state plays an analogue role to the |reseed_required_flag| in
Appendix B.3.4 of [NIST SP 800-90A Rev. 1]. The latter is a local variable,
the scope of which is limited to the RAND_DRBG_generate() function. Hence there
is no need for a DRBG_RESEED state outside of the generate function. This state
was removed and replaced by a local variable |reseed_required|.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Ben Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/4328)
---

diff --git a/crypto/rand/drbg_lib.c b/crypto/rand/drbg_lib.c
index eef5e11cc5..0042a931b0 100644
--- a/crypto/rand/drbg_lib.c
+++ b/crypto/rand/drbg_lib.c
@@ -356,6 +356,8 @@ int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen,
                        int prediction_resistance,
                        const unsigned char *adin, size_t adinlen)
 {
+    int reseed_required = 0;
+
     if (drbg->state != DRBG_READY) {
         /* try to recover from previous errors */
         rand_drbg_restart(drbg, NULL, 0, 0);
@@ -381,13 +383,13 @@ int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen,
 
     if (drbg->fork_count != rand_fork_count) {
         drbg->fork_count = rand_fork_count;
-        drbg->state = DRBG_RESEED;
+        reseed_required = 1;
     }
 
     if (drbg->reseed_counter >= drbg->reseed_interval)
-        drbg->state = DRBG_RESEED;
+        reseed_required = 1;
 
-    if (drbg->state == DRBG_RESEED || prediction_resistance) {
+    if (reseed_required || prediction_resistance) {
         if (!RAND_DRBG_reseed(drbg, adin, adinlen)) {
             RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_RESEED_ERROR);
             return 0;
@@ -402,10 +404,8 @@ int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen,
         return 0;
     }
 
-    if (drbg->reseed_counter >= drbg->reseed_interval)
-        drbg->state = DRBG_RESEED;
-    else
-        drbg->reseed_counter++;
+    drbg->reseed_counter++;
+
     return 1;
 }
 
diff --git a/crypto/rand/rand_lcl.h b/crypto/rand/rand_lcl.h
index 10a6f00a2d..5e319d8c99 100644
--- a/crypto/rand/rand_lcl.h
+++ b/crypto/rand/rand_lcl.h
@@ -41,7 +41,6 @@
 typedef enum drbg_status_e {
     DRBG_UNINITIALISED,
     DRBG_READY,
-    DRBG_RESEED,
     DRBG_ERROR
 } DRBG_STATUS;