Initial Commit

iTechSharp/srcbc/crypto/prng/DigestRandomGenerator.cs

@@ -0,0 +1,107 @@
+using System;
+
+using Org.BouncyCastle.Crypto.Digests;
+
+namespace Org.BouncyCastle.Crypto.Prng
+{
+	/**
+	 * Random generation based on the digest with counter. Calling addSeedMaterial will
+	 * always increase the entropy of the hash.
+	 * <p>
+	 * Internal access to the digest is syncrhonized so a single one of these can be shared.
+	 * </p>
+	 */
+	public class DigestRandomGenerator
+		: IRandomGenerator
+	{
+		private long	counter;
+		private IDigest	digest;
+		private byte[]	state;
+
+		public DigestRandomGenerator(
+			IDigest digest)
+		{
+			this.digest = digest;
+			this.state = new byte[digest.GetDigestSize()];
+			this.counter = 1;
+		}
+
+		public void AddSeedMaterial(
+			byte[] inSeed)
+		{
+			lock (this)
+			{
+				DigestUpdate(inSeed);
+			}
+		}
+
+		public void AddSeedMaterial(
+			long rSeed)
+		{
+			lock (this)
+			{
+				for (int i = 0; i != 8; i++)
+				{
+					DigestUpdate((byte)rSeed);
+//					rSeed >>>= 8;
+					rSeed >>= 8;
+				}
+			}
+		}
+
+		public void NextBytes(
+			byte[] bytes)
+		{
+			NextBytes(bytes, 0, bytes.Length);
+		}
+
+		public void NextBytes(
+			byte[]	bytes,
+			int		start,
+			int		len)
+		{
+			lock (this)
+			{
+				int stateOff = 0;
+
+				DigestDoFinal(state);
+
+				int end = start + len;
+				for (int i = start; i < end; ++i)
+				{
+					if (stateOff == state.Length)
+					{
+						DigestUpdate(counter++);
+						DigestUpdate(state);
+						DigestDoFinal(state);
+						stateOff = 0;
+					}
+					bytes[i] = state[stateOff++];
+				}
+
+				DigestUpdate(counter++);
+				DigestUpdate(state);
+			}
+		}
+
+		private void DigestUpdate(long seed)
+		{
+			for (int i = 0; i != 8; i++)
+			{
+				digest.Update((byte)seed);
+//				seed >>>= 8;
+				seed >>= 8;
+			}
+		}
+
+		private void DigestUpdate(byte[] inSeed)
+		{
+			digest.BlockUpdate(inSeed, 0, inSeed.Length);
+		}
+
+		private void DigestDoFinal(byte[] result)
+		{
+			digest.DoFinal(result, 0);
+		}
+	}
+}