Merge #9792: FastRandomContext improvements and switch to ChaCha20

4fd2d2f Add a FastRandomContext::randrange and use it (Pieter Wuille)
1632922 Switch FastRandomContext to ChaCha20 (Pieter Wuille)
e04326f Add ChaCha20 (Pieter Wuille)
663fbae FastRandom benchmark (Pieter Wuille)
c21cbe6 Introduce FastRandomContext::randbool() (Pieter Wuille)

Tree-SHA512: 7fff61e3f6d6dc6ac846ca643d877b377db609646dd401a0e8f50b052c6b9bcd2f5fc34de6bbf28f04afd1724f6279ee163ead5f37d724fb782a00239f35db1d

1 files changed, 18 insertions, 15 deletions

diff --git a/src/random.cpp b/src/random.cpp
index 6bcd0a70ba..6187f16290 100644
--- a/src/random.cpp
+++ b/src/random.cpp
@@ -240,22 +240,16 @@ uint256 GetRandHash()
     return hash;
 }
 
-FastRandomContext::FastRandomContext(bool fDeterministic)
+void FastRandomContext::RandomSeed()
 {
-    // The seed values have some unlikely fixed points which we avoid.
-    if (fDeterministic) {
-        Rz = Rw = 11;
-    } else {
-        uint32_t tmp;
-        do {
-            GetRandBytes((unsigned char*)&tmp, 4);
-        } while (tmp == 0 || tmp == 0x9068ffffU);
-        Rz = tmp;
-        do {
-            GetRandBytes((unsigned char*)&tmp, 4);
-        } while (tmp == 0 || tmp == 0x464fffffU);
-        Rw = tmp;
-    }
+    uint256 seed = GetRandHash();
+    rng.SetKey(seed.begin(), 32);
+    requires_seed = false;
+}
+
+FastRandomContext::FastRandomContext(const uint256& seed) : requires_seed(false), bytebuf_size(0), bitbuf_size(0)
+{
+    rng.SetKey(seed.begin(), 32);
 }
 
 bool Random_SanityCheck()
@@ -288,3 +282,12 @@ bool Random_SanityCheck()
     } while (num_overwritten < NUM_OS_RANDOM_BYTES && tries < MAX_TRIES);
     return (num_overwritten == NUM_OS_RANDOM_BYTES); /* If this failed, bailed out after too many tries */
 }
+
+FastRandomContext::FastRandomContext(bool fDeterministic) : requires_seed(!fDeterministic), bytebuf_size(0), bitbuf_size(0)
+{
+    if (!fDeterministic) {
+        return;
+    }
+    uint256 seed;
+    rng.SetKey(seed.begin(), 32);
+}