107 lines
2.4 KiB
C#
107 lines
2.4 KiB
C#
namespace ASC.Common.Security;
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public class AscRandom : Random
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{
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private const int Mbig = int.MaxValue;
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private const int Mseed = 161803398;
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private const int Mz = 0;
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private int _inext;
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private int _inextp;
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private readonly int[] _seeds;
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public AscRandom() : this(Environment.TickCount) { }
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public AscRandom(int seed)
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{
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_seeds = new int[56];
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var num4 = (seed == int.MinValue) ? int.MaxValue : Math.Abs(seed);
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var num2 = 161803398 - num4;
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_seeds[^1] = num2;
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var num3 = 1;
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for (var i = 1; i < _seeds.Length - 1; i++)
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{
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var index = 21 * i % (_seeds.Length - 1);
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_seeds[index] = num3;
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num3 = num2 - num3;
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if (num3 < 0)
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{
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num3 += int.MaxValue;
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}
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num2 = _seeds[index];
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}
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for (var j = 1; j < 5; j++)
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{
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for (var k = 1; k < _seeds.Length; k++)
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{
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_seeds[k] -= _seeds[1 + ((k + 30) % (_seeds.Length - 1))];
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if (_seeds[k] < 0)
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{
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_seeds[k] += int.MaxValue;
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}
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}
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}
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_inext = 0;
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_inextp = 21;
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}
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public override int Next(int maxValue)
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{
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if (maxValue < 0)
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{
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throw new ArgumentOutOfRangeException(nameof(maxValue));
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}
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return (int)(InternalSample() * 4.6566128752457969E-10 * maxValue);
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}
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public override void NextBytes(byte[] buffer)
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{
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ArgumentNullException.ThrowIfNull(buffer);
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for (var i = 0; i < buffer.Length; i++)
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{
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buffer[i] = (byte)(InternalSample() % (byte.MaxValue + 1));
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}
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}
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private int InternalSample()
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{
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var inext = _inext;
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var inextp = _inextp;
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if (++inext >= _seeds.Length - 1)
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{
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inext = 1;
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}
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if (++inextp >= _seeds.Length - 1)
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{
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inextp = 1;
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}
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var num = _seeds[inext] - _seeds[inextp];
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if (num == int.MaxValue)
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{
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num--;
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}
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if (num < 0)
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{
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num += int.MaxValue;
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}
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_seeds[inext] = num;
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_inext = inext;
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_inextp = inextp;
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return num;
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}
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} |