XteaEngine
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Crypto.Utilities;
using Org.BouncyCastle.Utilities;
using System;
namespace Org.BouncyCastle.Crypto.Engines
{
public class XteaEngine : IBlockCipher
{
private const int rounds = 32;
private const int block_size = 8;
private const int delta = -1640531527;
private uint[] _S = new uint[4];
private uint[] _sum0 = new uint[32];
private uint[] _sum1 = new uint[32];
private bool _initialised;
private bool _forEncryption;
public virtual string AlgorithmName => "XTEA";
public XteaEngine()
{
_initialised = false;
}
public virtual int GetBlockSize()
{
return 8;
}
public virtual void Init(bool forEncryption, ICipherParameters parameters)
{
if (!(parameters is KeyParameter))
throw new ArgumentException("invalid parameter passed to TEA init - " + Platform.GetTypeName(parameters));
_forEncryption = forEncryption;
_initialised = true;
KeyParameter keyParameter = (KeyParameter)parameters;
setKey(keyParameter.GetKey());
}
public virtual int ProcessBlock(byte[] inBytes, int inOff, byte[] outBytes, int outOff)
{
if (!_initialised)
throw new InvalidOperationException(AlgorithmName + " not initialised");
Check.DataLength(inBytes, inOff, 8, "input buffer too short");
Check.OutputLength(outBytes, outOff, 8, "output buffer too short");
if (!_forEncryption)
return DecryptBlock(inBytes.AsSpan(inOff), outBytes.AsSpan(outOff));
return EncryptBlock(inBytes.AsSpan(inOff), outBytes.AsSpan(outOff));
}
public virtual int ProcessBlock(ReadOnlySpan<byte> input, Span<byte> output)
{
if (!_initialised)
throw new InvalidOperationException(AlgorithmName + " not initialised");
Check.DataLength(input, 8, "input buffer too short");
Check.OutputLength(output, 8, "output buffer too short");
if (!_forEncryption)
return DecryptBlock(input, output);
return EncryptBlock(input, output);
}
private void setKey(byte[] key)
{
int num;
int num2 = num = 0;
while (num2 < 4) {
_S[num2] = Pack.BE_To_UInt32(key, num);
num2++;
num += 4;
}
for (num2 = (num = 0); num2 < 32; num2++) {
_sum0[num2] = (uint)(num + (int)_S[num & 3]);
num += -1640531527;
_sum1[num2] = (uint)(num + (int)_S[(num >> 11) & 3]);
}
}
private int EncryptBlock(ReadOnlySpan<byte> input, Span<byte> output)
{
uint num = Pack.BE_To_UInt32(input);
uint num2 = Pack.BE_To_UInt32(input.Slice(4, input.Length - 4));
for (int i = 0; i < 32; i++) {
num += ((((num2 << 4) ^ (num2 >> 5)) + num2) ^ _sum0[i]);
num2 += ((((num << 4) ^ (num >> 5)) + num) ^ _sum1[i]);
}
Pack.UInt32_To_BE(num, output);
Pack.UInt32_To_BE(num2, output.Slice(4, output.Length - 4));
return 8;
}
private int DecryptBlock(ReadOnlySpan<byte> input, Span<byte> output)
{
uint num = Pack.BE_To_UInt32(input);
uint num2 = Pack.BE_To_UInt32(input.Slice(4, input.Length - 4));
for (int num3 = 31; num3 >= 0; num3--) {
num2 -= ((((num << 4) ^ (num >> 5)) + num) ^ _sum1[num3]);
num -= ((((num2 << 4) ^ (num2 >> 5)) + num2) ^ _sum0[num3]);
}
Pack.UInt32_To_BE(num, output);
Pack.UInt32_To_BE(num2, output.Slice(4, output.Length - 4));
return 8;
}
}
}