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using System;
using Org.BouncyCastle.Crypto.Engines;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Utilities;
namespace Org.BouncyCastle.Crypto.Macs
{
/**
* implementation of DSTU 7624 MAC
*/
public class Dstu7624Mac : IMac
{
private int macSize;
private Dstu7624Engine engine;
private int blockSize;
private byte[] c, cTemp, kDelta;
private byte[] buf;
private int bufOff;
public Dstu7624Mac(int blockSizeBits, int q)
{
engine = new Dstu7624Engine(blockSizeBits);
blockSize = blockSizeBits / 8;
macSize = q / 8;
c = new byte[blockSize];
cTemp = new byte[blockSize];
kDelta = new byte[blockSize];
buf = new byte[blockSize];
}
public void Init(ICipherParameters parameters)
{
if (parameters is KeyParameter)
{
engine.Init(true, (KeyParameter)parameters);
engine.ProcessBlock(kDelta, 0, kDelta, 0);
}
else
{
throw new ArgumentException("invalid parameter passed to Dstu7624Mac init - "
+ Platform.GetTypeName(parameters));
}
}
public string AlgorithmName
{
get { return "Dstu7624Mac"; }
}
public int GetMacSize()
{
return macSize;
}
public void Update(byte input)
{
if (bufOff == buf.Length)
{
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
ProcessBlock(buf);
#else
ProcessBlock(buf, 0);
#endif
bufOff = 0;
}
buf[bufOff++] = input;
}
public void BlockUpdate(byte[] input, int inOff, int len)
{
if (len < 0)
throw new ArgumentException("Can't have a negative input length!");
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
BlockUpdate(input.AsSpan(inOff, len));
#else
int blockSize = engine.GetBlockSize();
int gapLen = blockSize - bufOff;
if (len > gapLen)
{
Array.Copy(input, inOff, buf, bufOff, gapLen);
ProcessBlock(buf, 0);
bufOff = 0;
len -= gapLen;
inOff += gapLen;
while (len > blockSize)
{
ProcessBlock(input, inOff);
len -= blockSize;
inOff += blockSize;
}
}
Array.Copy(input, inOff, buf, bufOff, len);
bufOff += len;
#endif
}
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
public void BlockUpdate(ReadOnlySpan<byte> input)
{
int blockSize = engine.GetBlockSize();
int gapLen = blockSize - bufOff;
if (input.Length > gapLen)
{
input[..gapLen].CopyTo(buf.AsSpan(bufOff));
ProcessBlock(buf);
bufOff = 0;
input = input[gapLen..];
while (input.Length > blockSize)
{
ProcessBlock(input);
input = input[blockSize..];
}
}
input.CopyTo(buf.AsSpan(bufOff));
bufOff += input.Length;
}
#endif
#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1_OR_GREATER
private void ProcessBlock(ReadOnlySpan<byte> input)
{
Xor(c, input, cTemp);
engine.ProcessBlock(cTemp, c);
}
private void Xor(ReadOnlySpan<byte> c, ReadOnlySpan<byte> input, Span<byte> xorResult)
{
for (int byteIndex = 0; byteIndex < blockSize; byteIndex++)
{
xorResult[byteIndex] = (byte)(c[byteIndex] ^ input[byteIndex]);
}
}
#else
private void ProcessBlock(byte[] input, int inOff)
{
Xor(c, 0, input, inOff, cTemp);
engine.ProcessBlock(cTemp, 0, c, 0);
}
#endif
private void Xor(byte[] c, int cOff, byte[] input, int inOff, byte[] xorResult)
{
for (int byteIndex = 0; byteIndex < blockSize; byteIndex++)
{
xorResult[byteIndex] = (byte)(c[byteIndex + cOff] ^ input[byteIndex + inOff]);
}
}
public int DoFinal(byte[] output, int outOff)
{
if (bufOff % buf.Length != 0)
throw new DataLengthException("Input must be a multiple of blocksize");
//Last block
Xor(c, 0, buf, 0, cTemp);
Xor(cTemp, 0, kDelta, 0, c);
engine.ProcessBlock(c, 0, c, 0);
if (macSize + outOff > output.Length)
throw new DataLengthException("Output buffer too short");
Array.Copy(c, 0, output, outOff, macSize);
return macSize;
}
public void Reset()
{
Arrays.Fill(c, (byte)0x00);
Arrays.Fill(cTemp, (byte)0x00);
Arrays.Fill(kDelta, (byte)0x00);
Arrays.Fill(buf, (byte)0x00);
engine.Reset();
engine.ProcessBlock(kDelta, 0, kDelta, 0);
bufOff = 0;
}
}
}
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