1 files changed, 71 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..31a8461f0
--- /dev/null
+++ b/crypto/src/crypto/prng/BasicEntropySourceProvider.cs
@@ -0,0 +1,71 @@
+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()
+ {
+ // TODO[FIPS] Not all SecureRandom implementations are considered valid entropy sources
+ return SecureRandom.GetNextBytes(mSecureRandom, (mEntropySize + 7) / 8);
+ }
+
+ int IEntropySource.EntropySize
+ {
+ get { return mEntropySize; }
+ }
+ }
+ }
+}
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