#if !BESTHTTP_DISABLE_ALTERNATE_SSL && (!UNITY_WEBGL || UNITY_EDITOR)
using System;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Utilities;
namespace Org.BouncyCastle.Crypto.Engines
{
/**
* An RC6 engine.
*/
public class RC6Engine
: IBlockCipher
{
private static readonly int wordSize = 32;
private static readonly int bytesPerWord = wordSize / 8;
/*
* the number of rounds to perform
*/
private static readonly int _noRounds = 20;
/*
* the expanded key array of size 2*(rounds + 1)
*/
private int [] _S;
/*
* our "magic constants" for wordSize 32
*
* Pw = Odd((e-2) * 2^wordsize)
* Qw = Odd((o-2) * 2^wordsize)
*
* where e is the base of natural logarithms (2.718281828...)
* and o is the golden ratio (1.61803398...)
*/
private static readonly int P32 = unchecked((int) 0xb7e15163);
private static readonly int Q32 = unchecked((int) 0x9e3779b9);
private static readonly int LGW = 5; // log2(32)
private bool forEncryption;
/**
* Create an instance of the RC6 encryption algorithm
* and set some defaults
*/
public RC6Engine()
{
// _S = null;
}
public virtual string AlgorithmName
{
get { return "RC6"; }
}
public virtual bool IsPartialBlockOkay
{
get { return false; }
}
public virtual int GetBlockSize()
{
return 4 * bytesPerWord;
}
/**
* initialise a RC5-32 cipher.
*
* @param forEncryption whether or not we are for encryption.
* @param parameters the parameters required to set up the cipher.
* @exception ArgumentException if the parameters argument is
* inappropriate.
*/
public virtual void Init(
bool forEncryption,
ICipherParameters parameters)
{
if (!(parameters is KeyParameter))
throw new ArgumentException("invalid parameter passed to RC6 init - " + Org.BouncyCastle.Utilities.Platform.GetTypeName(parameters));
this.forEncryption = forEncryption;
KeyParameter p = (KeyParameter)parameters;
SetKey(p.GetKey());
}
public virtual int ProcessBlock(
byte[] input,
int inOff,
byte[] output,
int outOff)
{
int blockSize = GetBlockSize();
if (_S == null)
throw new InvalidOperationException("RC6 engine not initialised");
Check.DataLength(input, inOff, blockSize, "input buffer too short");
Check.OutputLength(output, outOff, blockSize, "output buffer too short");
return (forEncryption)
? EncryptBlock(input, inOff, output, outOff)
: DecryptBlock(input, inOff, output, outOff);
}
public virtual void Reset()
{
}
/**
* Re-key the cipher.
*
* @param inKey the key to be used
*/
private void SetKey(
byte[] key)
{
//
// KEY EXPANSION:
//
// There are 3 phases to the key expansion.
//
// Phase 1:
// Copy the secret key K[0...b-1] into an array L[0..c-1] of
// c = ceil(b/u), where u = wordSize/8 in little-endian order.
// In other words, we fill up L using u consecutive key bytes
// of K. Any unfilled byte positions in L are zeroed. In the
// case that b = c = 0, set c = 1 and L[0] = 0.
//
// compute number of dwords
int c = (key.Length + (bytesPerWord - 1)) / bytesPerWord;
if (c == 0)
{
c = 1;
}
int[] L = new int[(key.Length + bytesPerWord - 1) / bytesPerWord];
// load all key bytes into array of key dwords
for (int i = key.Length - 1; i >= 0; i--)
{
L[i / bytesPerWord] = (L[i / bytesPerWord] << 8) + (key[i] & 0xff);
}
//
// Phase 2:
// Key schedule is placed in a array of 2+2*ROUNDS+2 = 44 dwords.
// Initialize S to a particular fixed pseudo-random bit pattern
// using an arithmetic progression modulo 2^wordsize determined
// by the magic numbers, Pw & Qw.
//
_S = new int[2+2*_noRounds+2];
_S[0] = P32;
for (int i=1; i < _S.Length; i++)
{
_S[i] = (_S[i-1] + Q32);
}
//
// Phase 3:
// Mix in the user's secret key in 3 passes over the arrays S & L.
// The max of the arrays sizes is used as the loop control
//
int iter;
if (L.Length > _S.Length)
{
iter = 3 * L.Length;
}
else
{
iter = 3 * _S.Length;
}
int A = 0;
int B = 0;
int ii = 0, jj = 0;
for (int k = 0; k < iter; k++)
{
A = _S[ii] = RotateLeft(_S[ii] + A + B, 3);
B = L[jj] = RotateLeft( L[jj] + A + B, A+B);
ii = (ii+1) % _S.Length;
jj = (jj+1) % L.Length;
}
}
private int EncryptBlock(
byte[] input,
int inOff,
byte[] outBytes,
int outOff)
{
// load A,B,C and D registers from in.
int A = BytesToWord(input, inOff);
int B = BytesToWord(input, inOff + bytesPerWord);
int C = BytesToWord(input, inOff + bytesPerWord*2);
int D = BytesToWord(input, inOff + bytesPerWord*3);
// Do pseudo-round #0: pre-whitening of B and D
B += _S[0];
D += _S[1];
// perform round #1,#2 ... #ROUNDS of encryption
for (int i = 1; i <= _noRounds; i++)
{
int t = 0,u = 0;
t = B*(2*B+1);
t = RotateLeft(t,5);
u = D*(2*D+1);
u = RotateLeft(u,5);
A ^= t;
A = RotateLeft(A,u);
A += _S[2*i];
C ^= u;
C = RotateLeft(C,t);
C += _S[2*i+1];
int temp = A;
A = B;
B = C;
C = D;
D = temp;
}
// do pseudo-round #(ROUNDS+1) : post-whitening of A and C
A += _S[2*_noRounds+2];
C += _S[2*_noRounds+3];
// store A, B, C and D registers to out
WordToBytes(A, outBytes, outOff);
WordToBytes(B, outBytes, outOff + bytesPerWord);
WordToBytes(C, outBytes, outOff + bytesPerWord*2);
WordToBytes(D, outBytes, outOff + bytesPerWord*3);
return 4 * bytesPerWord;
}
private int DecryptBlock(
byte[] input,
int inOff,
byte[] outBytes,
int outOff)
{
// load A,B,C and D registers from out.
int A = BytesToWord(input, inOff);
int B = BytesToWord(input, inOff + bytesPerWord);
int C = BytesToWord(input, inOff + bytesPerWord*2);
int D = BytesToWord(input, inOff + bytesPerWord*3);
// Undo pseudo-round #(ROUNDS+1) : post whitening of A and C
C -= _S[2*_noRounds+3];
A -= _S[2*_noRounds+2];
// Undo round #ROUNDS, .., #2,#1 of encryption
for (int i = _noRounds; i >= 1; i--)
{
int t=0,u = 0;
int temp = D;
D = C;
C = B;
B = A;
A = temp;
t = B*(2*B+1);
t = RotateLeft(t, LGW);
u = D*(2*D+1);
u = RotateLeft(u, LGW);
C -= _S[2*i+1];
C = RotateRight(C,t);
C ^= u;
A -= _S[2*i];
A = RotateRight(A,u);
A ^= t;
}
// Undo pseudo-round #0: pre-whitening of B and D
D -= _S[1];
B -= _S[0];
WordToBytes(A, outBytes, outOff);
WordToBytes(B, outBytes, outOff + bytesPerWord);
WordToBytes(C, outBytes, outOff + bytesPerWord*2);
WordToBytes(D, outBytes, outOff + bytesPerWord*3);
return 4 * bytesPerWord;
}
//////////////////////////////////////////////////////////////
//
// PRIVATE Helper Methods
//
//////////////////////////////////////////////////////////////
/**
* Perform a left "spin" of the word. The rotation of the given
* word x is rotated left by y bits.
* Only the lg(wordSize) low-order bits of y
* are used to determine the rotation amount. Here it is
* assumed that the wordsize used is a power of 2.
*
* @param x word to rotate
* @param y number of bits to rotate % wordSize
*/
private int RotateLeft(int x, int y)
{
return ((int)((uint)(x << (y & (wordSize-1)))
| ((uint) x >> (wordSize - (y & (wordSize-1))))));
}
/**
* Perform a right "spin" of the word. The rotation of the given
* word x is rotated left by y bits.
* Only the lg(wordSize) low-order bits of y
* are used to determine the rotation amount. Here it is
* assumed that the wordsize used is a power of 2.
*
* @param x word to rotate
* @param y number of bits to rotate % wordSize
*/
private int RotateRight(int x, int y)
{
return ((int)(((uint) x >> (y & (wordSize-1)))
| (uint)(x << (wordSize - (y & (wordSize-1))))));
}
private int BytesToWord(
byte[] src,
int srcOff)
{
int word = 0;
for (int i = bytesPerWord - 1; i >= 0; i--)
{
word = (word << 8) + (src[i + srcOff] & 0xff);
}
return word;
}
private void WordToBytes(
int word,
byte[] dst,
int dstOff)
{
for (int i = 0; i < bytesPerWord; i++)
{
dst[i + dstOff] = (byte)word;
word = (int) ((uint) word >> 8);
}
}
}
}
#endif