Use custom SecureRandom instance

[signal-cli] / src / main / java / org / asamk / signal / util / RandomUtils.java

diff --git a/src/main/java/org/asamk/signal/util/RandomUtils.java b/src/main/java/org/asamk/signal/util/RandomUtils.java
new file mode 100644 (file)
index 0000000..d0463b4
--- /dev/null
+++ b/src/main/java/org/asamk/signal/util/RandomUtils.java
@@ -0,0 +1,37 @@
+package org.asamk.signal.util;
+
+import java.security.NoSuchAlgorithmException;
+import java.security.SecureRandom;
+
+public class RandomUtils {
+
+    private static final ThreadLocal<SecureRandom> LOCAL_RANDOM = new ThreadLocal<SecureRandom>() {
+        @Override
+        protected SecureRandom initialValue() {
+            SecureRandom rand = getSecureRandomUnseeded();
+
+            // Let the SecureRandom seed it self initially
+            rand.nextBoolean();
+
+            return rand;
+        }
+    };
+
+    private static SecureRandom getSecureRandomUnseeded() {
+        try {
+            return SecureRandom.getInstance("NativePRNG");
+        } catch (NoSuchAlgorithmException e) {
+            // Fallback to SHA1PRNG if NativePRNG is not available (e.g. on windows)
+            try {
+                return SecureRandom.getInstance("SHA1PRNG");
+            } catch (NoSuchAlgorithmException e1) {
+                // Fallback to default
+                return new SecureRandom();
+            }
+        }
+    }
+
+    public static SecureRandom getSecureRandom() {
+        return LOCAL_RANDOM.get();
+    }
+}