merged 1.81.1 - DRBG with org.bouncycastle.drbg.effective_256bits_entropy property for entropy adjustment.

Author: dghgit

prov/src/main/java/org/bouncycastle/jcajce/provider/drbg/DRBG.java

@@ -53,6 +53,14 @@ public class DRBG
 {
     private static final String PREFIX = DRBG.class.getName();
 
+    private static int get256BitsEffectiveEntropySize()
+    {
+        // by default we assume .9 bits per real bit
+        int effectiveBits = Properties.asInteger("org.bouncycastle.drbg.effective_256bits_entropy", 282);
+
+        return ((effectiveBits + 7) / 8) * 8;
+    }
+
     // {"Provider class name","SecureRandomSpi class name"}
     private static final String[][] initialEntropySourceNames = new String[][]
         {
@@ -463,7 +471,7 @@ private static class HybridEntropySource
             EntropySourceProvider entropyProvider = createCoreEntropySourceProvider();
             bytesRequired = (bitsRequired + 7) / 8;
             // remember for the seed generator we need the correct security strength for SHA-512
-            entropySource = new SignallingEntropySource(entropyDaemon, seedAvailable, entropyProvider, 256);
+            entropySource = new SignallingEntropySource(entropyDaemon, seedAvailable, entropyProvider, get256BitsEffectiveEntropySize());
             drbg = new SP800SecureRandomBuilder(new EntropySourceProvider()
             {
                 public EntropySource get(final int bitsRequired)
@@ -592,7 +600,7 @@ private static class OneShotHybridEntropySource
             EntropySourceProvider entropyProvider = createCoreEntropySourceProvider();
             bytesRequired = (bitsRequired + 7) / 8;
             // remember for the seed generator we need the correct security strength for SHA-512
-            entropySource = new OneShotSignallingEntropySource(seedAvailable, entropyProvider, 256);
+            entropySource = new OneShotSignallingEntropySource(seedAvailable, entropyProvider, get256BitsEffectiveEntropySize());
             drbg = new SP800SecureRandomBuilder(new EntropySourceProvider()
             {
                 public EntropySource get(final int bitsRequired)