init commit

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Crypto/Prng/X931SecureRandomBuilder.cs

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+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Crypto.Utilities;
+using Org.BouncyCastle.Security;
+using Org.BouncyCastle.Utilities.Date;
+
+namespace Org.BouncyCastle.Crypto.Prng;
+
+public class X931SecureRandomBuilder
+{
+	private readonly SecureRandom mRandom;
+
+	private IEntropySourceProvider mEntropySourceProvider;
+
+	private byte[] mDateTimeVector;
+
+	public X931SecureRandomBuilder()
+		: this(new SecureRandom(), predictionResistant: false)
+	{
+	}
+
+	public X931SecureRandomBuilder(SecureRandom entropySource, bool predictionResistant)
+	{
+		mRandom = entropySource;
+		mEntropySourceProvider = new BasicEntropySourceProvider(mRandom, predictionResistant);
+	}
+
+	public X931SecureRandomBuilder(IEntropySourceProvider entropySourceProvider)
+	{
+		mRandom = null;
+		mEntropySourceProvider = entropySourceProvider;
+	}
+
+	public X931SecureRandomBuilder SetDateTimeVector(byte[] dateTimeVector)
+	{
+		mDateTimeVector = dateTimeVector;
+		return this;
+	}
+
+	public X931SecureRandom Build(IBlockCipher engine, KeyParameter key, bool predictionResistant)
+	{
+		if (mDateTimeVector == null)
+		{
+			mDateTimeVector = new byte[engine.GetBlockSize()];
+			Pack.UInt64_To_BE((ulong)DateTimeUtilities.CurrentUnixMs(), mDateTimeVector, 0);
+		}
+		engine.Init(forEncryption: true, key);
+		return new X931SecureRandom(mRandom, new X931Rng(engine, mDateTimeVector, mEntropySourceProvider.Get(engine.GetBlockSize() * 8)), predictionResistant);
+	}
+}