1 files changed, 70 insertions, 0 deletions
diff --git a/crypto/src/crypto/prng/BasicEntropySourceProvider.cs b/crypto/src/crypto/prng/BasicEntropySourceProvider.cs
new file mode 100644
index 000000000..0e929e0fd
--- /dev/null
+++ b/crypto/src/crypto/prng/BasicEntropySourceProvider.cs
@@ -0,0 +1,70 @@
+using System;
+
+using Org.BouncyCastle.Security;
+
+namespace Org.BouncyCastle.Crypto.Prng
+{
+    /**
+     * An EntropySourceProvider where entropy generation is based on a SecureRandom output using SecureRandom.generateSeed().
+     */
+    public class BasicEntropySourceProvider
+        :   IEntropySourceProvider
+    {
+        private readonly SecureRandom   mSecureRandom;
+        private readonly bool           mPredictionResistant;
+
+        /**
+         * Create a entropy source provider based on the passed in SecureRandom.
+         *
+         * @param secureRandom 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 secureRandom, bool isPredictionResistant)
+        {
+            mSecureRandom = secureRandom;
+            mPredictionResistant = 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 IEntropySource Get(int bitsRequired)
+        {
+            return new BasicEntropySource(mSecureRandom, mPredictionResistant, bitsRequired);
+        }
+
+        private class BasicEntropySource
+            :   IEntropySource
+        {
+            private readonly SecureRandom   mSecureRandom;
+            private readonly bool           mPredictionResistant;
+            private readonly int            mEntropySize;
+
+            internal BasicEntropySource(SecureRandom secureRandom, bool predictionResistant, int entropySize)
+            {
+                this.mSecureRandom = secureRandom;
+                this.mPredictionResistant = predictionResistant;
+                this.mEntropySize = entropySize;
+            }
+
+            bool IEntropySource.IsPredictionResistant
+            {
+                get { return mPredictionResistant; }
+            }
+
+            byte[] IEntropySource.GetEntropy()
+            {
+                return mSecureRandom.GenerateSeed((mEntropySize + 7) / 8);
+            }
+
+            int IEntropySource.EntropySize
+            {
+                get { return mEntropySize; }
+            }
+        }
+    }
+}