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using System;
using System.IO;
#if NETSTANDARD1_0_OR_GREATER || NETCOREAPP1_0_OR_GREATER
using System.Runtime.CompilerServices;
#endif
using Org.BouncyCastle.Crypto.Utilities;
using Org.BouncyCastle.Utilities;
namespace Org.BouncyCastle.Crypto.Digests
{
public sealed class IsapDigest
: IDigest
{
private readonly MemoryStream buffer = new MemoryStream();
private ulong x0, x1, x2, x3, x4;
public string AlgorithmName => "ISAP Hash";
public int GetDigestSize() => 32;
public int GetByteLength() => 8;
public void Update(byte input)
{
buffer.WriteByte(input);
}
public void BlockUpdate(byte[] input, int inOff, int inLen)
{
Check.DataLength(input, inOff, inLen, "input buffer too short");
buffer.Write(input, inOff, inLen);
}
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
public void BlockUpdate(ReadOnlySpan<byte> input)
{
buffer.Write(input);
}
#endif
public int DoFinal(byte[] output, int outOff)
{
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
return DoFinal(output.AsSpan(outOff));
#else
Check.OutputLength(output, outOff, 32, "output buffer is too short");
/* init state */
x0 = 17191252062196199485UL;
x1 = 10066134719181819906UL;
x2 = 13009371945472744034UL;
x3 = 4834782570098516968UL;
x4 = 3787428097924915520UL;
byte[] input = buffer.GetBuffer();
int len = Convert.ToInt32(buffer.Length);
int pos = 0;
while (len >= 8)
{
x0 ^= Pack.BE_To_UInt64(input, pos);
pos += 8;
len -= 8;
P12();
}
x0 ^= 0x80UL << ((7 - len) << 3);
if (len > 0)
{
x0 ^= Pack.BE_To_UInt64_High(input, pos, len);
}
for (int i = 0; i < 4; ++i)
{
P12();
Pack.UInt64_To_BE(x0, output, outOff + (i << 3));
}
return 32;
#endif
}
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
public int DoFinal(Span<byte> output)
{
Check.OutputLength(output, 32, "output buffer is too short");
/* init state */
x0 = 17191252062196199485UL;
x1 = 10066134719181819906UL;
x2 = 13009371945472744034UL;
x3 = 4834782570098516968UL;
x4 = 3787428097924915520UL;
if (!buffer.TryGetBuffer(out var bufferContents))
throw new UnauthorizedAccessException();
var input = bufferContents.AsSpan();
while (input.Length >= 8)
{
x0 ^= Pack.BE_To_UInt64(input);
input = input[8..];
P12();
}
x0 ^= 0x80UL << ((7 - input.Length) << 3);
if (!input.IsEmpty)
{
x0 ^= Pack.BE_To_UInt64_High(input);
}
for (int i = 0; i < 4; ++i)
{
P12();
Pack.UInt64_To_BE(x0, output[(i << 3)..]);
}
return 32;
}
#endif
public void Reset()
{
buffer.SetLength(0);
}
private void P12()
{
ROUND(0xf0);
ROUND(0xe1);
ROUND(0xd2);
ROUND(0xc3);
ROUND(0xb4);
ROUND(0xa5);
ROUND(0x96);
ROUND(0x87);
ROUND(0x78);
ROUND(0x69);
ROUND(0x5a);
ROUND(0x4b);
}
#if NETSTANDARD1_0_OR_GREATER || NETCOREAPP1_0_OR_GREATER
[MethodImpl(MethodImplOptions.AggressiveInlining)]
#endif
private void ROUND(ulong C)
{
ulong t0 = x0 ^ x1 ^ x2 ^ x3 ^ C ^ (x1 & (x0 ^ x2 ^ x4 ^ C));
ulong t1 = x0 ^ x2 ^ x3 ^ x4 ^ C ^ ((x1 ^ x2 ^ C) & (x1 ^ x3));
ulong t2 = x1 ^ x2 ^ x4 ^ C ^ (x3 & x4);
ulong t3 = x0 ^ x1 ^ x2 ^ C ^ ((~x0) & (x3 ^ x4));
ulong t4 = x1 ^ x3 ^ x4 ^ ((x0 ^ x4) & x1);
x0 = t0 ^ Longs.RotateRight(t0, 19) ^ Longs.RotateRight(t0, 28);
x1 = t1 ^ Longs.RotateRight(t1, 39) ^ Longs.RotateRight(t1, 61);
x2 = ~(t2 ^ Longs.RotateRight(t2, 1) ^ Longs.RotateRight(t2, 6));
x3 = t3 ^ Longs.RotateRight(t3, 10) ^ Longs.RotateRight(t3, 17);
x4 = t4 ^ Longs.RotateRight(t4, 7) ^ Longs.RotateRight(t4, 41);
}
}
}
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