1 files changed, 53 insertions, 0 deletions
diff --git a/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/prng/BasicEntropySourceProvider.java b/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/prng/BasicEntropySourceProvider.java
new file mode 100644
index 000000000..176b5fb0f
--- /dev/null
+++ b/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/prng/BasicEntropySourceProvider.java
@@ -0,0 +1,53 @@
+package org.spongycastle.crypto.prng;
+
+import java.security.SecureRandom;
+
+/**
+ * An EntropySourceProvider where entropy generation is based on a SecureRandom output using SecureRandom.generateSeed().
+ */
+public class BasicEntropySourceProvider
+    implements EntropySourceProvider
+{
+    private final SecureRandom _sr;
+    private final boolean      _predictionResistant;
+
+    /**
+     * Create a entropy source provider based on the passed in SecureRandom.
+     *
+     * @param random the SecureRandom to base EntropySource construction on.
+     * @param isPredictionResistant boolean indicating if the SecureRandom is based on prediction resistant entropy or not (true if it is).
+     */
+    public BasicEntropySourceProvider(SecureRandom random, boolean isPredictionResistant)
+    {
+        _sr = random;
+        _predictionResistant = isPredictionResistant;
+    }
+
+    /**
+     * Return an entropy source that will create bitsRequired bits of entropy on
+     * each invocation of getEntropy().
+     *
+     * @param bitsRequired size (in bits) of entropy to be created by the provided source.
+     * @return an EntropySource that generates bitsRequired bits of entropy on each call to its getEntropy() method.
+     */
+    public EntropySource get(final int bitsRequired)
+    {
+        return new EntropySource()
+        {
+            public boolean isPredictionResistant()
+            {
+                return _predictionResistant;
+            }
+
+            public byte[] getEntropy()
+            {
+                return _sr.generateSeed((bitsRequired + 7) / 8);
+            }
+
+            public int entropySize()
+            {
+                return bitsRequired;
+            }
+        };
+    }
+}