From 1c31cf79388e74afbfc42d0a61a249409f1601c2 Mon Sep 17 00:00:00 2001
From: t-bast <bastuc@hotmail.fr>
Date: Thu, 22 Apr 2021 12:00:22 +0200
Subject: [PATCH] Sample entropy from more sources

---
 .../fr/acinq/eclair/crypto/WeakRandom.scala   | 51 +++++++++++--------
 1 file changed, 30 insertions(+), 21 deletions(-)

diff --git a/eclair-core/src/main/scala/fr/acinq/eclair/crypto/WeakRandom.scala b/eclair-core/src/main/scala/fr/acinq/eclair/crypto/WeakRandom.scala
index c3cacbee22..962ccbd9ca 100644
--- a/eclair-core/src/main/scala/fr/acinq/eclair/crypto/WeakRandom.scala
+++ b/eclair-core/src/main/scala/fr/acinq/eclair/crypto/WeakRandom.scala
@@ -21,6 +21,7 @@ import org.bouncycastle.crypto.digests.{SHA1Digest, SHA256Digest}
 import org.bouncycastle.crypto.engines.ChaCha7539Engine
 import org.bouncycastle.crypto.params.{KeyParameter, ParametersWithIV}
 
+import java.lang.management.ManagementFactory
 import java.nio.ByteOrder
 
 /**
@@ -36,36 +37,44 @@ class WeakRandom() {
   private val seed = new Array[Byte](32)
   private var opsSinceLastSample: Int = 0
 
+  private val memoryMXBean = ManagementFactory.getMemoryMXBean
+  private val runtimeMXBean = ManagementFactory.getRuntimeMXBean
+  private val threadMXBean = ManagementFactory.getThreadMXBean
+
   // sample some initial entropy
   sampleEntropy()
 
+  private def feedDigest(sha: SHA256Digest, i: Int): Unit = {
+    sha.update(i.toByte)
+    sha.update((i >> 8).toByte)
+    sha.update((i >> 16).toByte)
+    sha.update((i >> 24).toByte)
+  }
+
+  private def feedDigest(sha: SHA256Digest, l: Long): Unit = {
+    sha.update(l.toByte)
+    sha.update((l >> 8).toByte)
+    sha.update((l >> 16).toByte)
+    sha.update((l >> 24).toByte)
+    sha.update((l >> 32).toByte)
+    sha.update((l >> 40).toByte)
+  }
+
   /** The entropy pool is regularly enriched with newly sampled entropy. */
   private def sampleEntropy(): Unit = {
     opsSinceLastSample = 0
 
     val sha = new SHA256Digest()
     sha.update(seed, 0, 32)
-
-    // Sample current time.
-    val now = System.currentTimeMillis()
-    sha.update(now.toByte)
-    sha.update((now >> 8).toByte)
-    sha.update((now >> 16).toByte)
-    sha.update((now >> 24).toByte)
-
-    // Sample memory allocator.
-    val addr = System.identityHashCode(new Array[Int](1))
-    sha.update(addr.toByte)
-    sha.update((addr >> 8).toByte)
-    sha.update((addr >> 16).toByte)
-    sha.update((addr >> 24).toByte)
-
-    // Sample available memory.
-    val memory = Runtime.getRuntime.freeMemory()
-    sha.update(memory.toByte)
-    sha.update((memory >> 8).toByte)
-    sha.update((memory >> 16).toByte)
-    sha.update((memory >> 24).toByte)
+    feedDigest(sha, System.currentTimeMillis())
+    feedDigest(sha, System.identityHashCode(new Array[Int](1)))
+    feedDigest(sha, memoryMXBean.getHeapMemoryUsage.getUsed)
+    feedDigest(sha, memoryMXBean.getNonHeapMemoryUsage.getUsed)
+    feedDigest(sha, runtimeMXBean.getPid)
+    feedDigest(sha, runtimeMXBean.getUptime)
+    feedDigest(sha, threadMXBean.getCurrentThreadCpuTime)
+    feedDigest(sha, threadMXBean.getCurrentThreadUserTime)
+    feedDigest(sha, threadMXBean.getPeakThreadCount)
 
     sha.doFinal(seed, 0)
   }