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