From 3fd6253e13bda5489164eaa7c5ba9de491e47b83 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Fri, 17 Oct 2014 16:04:00 -0700
Subject: [PATCH] Better randomization for tests

---
 src/tests.c     | 23 ++++++++++++++++++++---
 src/util.h      |  3 +++
 src/util_impl.h | 21 +++++++++++++++++----
 3 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/src/tests.c b/src/tests.c
index 80ae0f4bf1..e5d27f72c7 100644
--- a/src/tests.c
+++ b/src/tests.c
@@ -19,7 +19,7 @@
 #include "openssl/obj_mac.h"
 #endif
 
-static int count = 100;
+static int count = 750;
 
 /***** NUM TESTS *****/
 
@@ -632,6 +632,7 @@ void test_ecdsa_end_to_end() {
     CHECK(secp256k1_ecdsa_recover_compact(message, 32, csignature, recpubkey, &recpubkeylen, pubkeylen == 33, recid) != 1 ||
           memcmp(pubkey, recpubkey, pubkeylen) != 0);
     CHECK(recpubkeylen == pubkeylen);
+
 }
 
 void run_ecdsa_end_to_end() {
@@ -698,10 +699,26 @@ void run_ecdsa_openssl() {
 #endif
 
 int main(int argc, char **argv) {
-    if (argc > 1)
-        count = strtol(argv[1], NULL, 0)*47;
+    // find iteration count
+    if (argc > 1) {
+        count = strtol(argv[1], NULL, 0);
+    }
+
+    // find random seed
+    uint64_t seed;
+    if (argc > 2) {
+        seed = strtoull(argv[2], NULL, 0);
+    } else {
+        FILE *frand = fopen("/dev/urandom", "r");
+        if (!frand || !fread(&seed, sizeof(seed), 1, frand)) {
+            seed = time(NULL) * 1337;
+        }
+        fclose(frand);
+    }
+    secp256k1_rand_seed(seed);
 
     printf("test count = %i\n", count);
+    printf("random seed = %llu\n", (unsigned long long)seed);
 
     // initialize
     secp256k1_start(SECP256K1_START_SIGN | SECP256K1_START_VERIFY);
diff --git a/src/util.h b/src/util.h
index 122889577e..c859523f49 100644
--- a/src/util.h
+++ b/src/util.h
@@ -43,6 +43,9 @@
 #define VERIFY_CHECK(cond) do { (cond); } while(0)
 #endif
 
+/** Seed the pseudorandom number generator. */
+static inline void secp256k1_rand_seed(uint64_t v);
+
 /** Generate a pseudorandom 32-bit number. */
 static uint32_t secp256k1_rand32(void);
 
diff --git a/src/util_impl.h b/src/util_impl.h
index 58750f8cfc..482fb31b1a 100644
--- a/src/util_impl.h
+++ b/src/util_impl.h
@@ -10,11 +10,24 @@
 
 #include "util.h"
 
+static uint32_t secp256k1_Rz = 11, secp256k1_Rw = 11;
+
+static inline void secp256k1_rand_seed(uint64_t v) {
+    secp256k1_Rz = v >> 32;
+    secp256k1_Rw = v;
+
+    if (secp256k1_Rz == 0 || secp256k1_Rz == 0x9068ffffU) {
+        secp256k1_Rz = 111;
+    }
+    if (secp256k1_Rw == 0 || secp256k1_Rw == 0x464fffffU) {
+        secp256k1_Rw = 111;
+    }
+}
+
 static inline uint32_t secp256k1_rand32(void) {
-    static uint32_t Rz = 11, Rw = 11;
-    Rz = 36969 * (Rz & 0xFFFF) + (Rz >> 16);
-    Rw = 18000 * (Rw & 0xFFFF) + (Rw >> 16);
-    return (Rw << 16) + (Rw >> 16) + Rz;
+    secp256k1_Rz = 36969 * (secp256k1_Rz & 0xFFFF) + (secp256k1_Rz >> 16);
+    secp256k1_Rw = 18000 * (secp256k1_Rw & 0xFFFF) + (secp256k1_Rw >> 16);
+    return (secp256k1_Rw << 16) + (secp256k1_Rw >> 16) + secp256k1_Rz;
 }
 
 static void secp256k1_rand256(unsigned char *b32) {