#if !BESTHTTP_DISABLE_ALTERNATE_SSL && (!UNITY_WEBGL || UNITY_EDITOR)
using System;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Utilities;
#if UNITY_WSA && !UNITY_EDITOR && !ENABLE_IL2CPP
using System.TypeFix;
#endif
namespace Org.BouncyCastle.Crypto.Engines
{
/**
* The specification for RC5 came from the <code>RC5 Encryption Algorithm</code>
* publication in RSA CryptoBytes, Spring of 1995.
* <em>http://www.rsasecurity.com/rsalabs/cryptobytes</em>.
* <p>
* This implementation has a word size of 32 bits.</p>
*/
public class RC532Engine
: IBlockCipher
{
/*
* the number of rounds to perform
*/
private int _noRounds;
/*
* the expanded key array of size 2*(rounds + 1)
*/
private int [] _S;
/*
* our "magic constants" for 32 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 bool forEncryption;
/**
* Create an instance of the RC5 encryption algorithm
* and set some defaults
*/
public RC532Engine()
{
_noRounds = 12; // the default
// _S = null;
}
public virtual string AlgorithmName
{
get { return "RC5-32"; }
}
public virtual bool IsPartialBlockOkay
{
get { return false; }
}
public virtual int GetBlockSize()
{
return 2 * 4;
}
/**
* 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 (typeof(RC5Parameters).IsInstanceOfType(parameters))
{
RC5Parameters p = (RC5Parameters)parameters;
_noRounds = p.Rounds;
SetKey(p.GetKey());
}
else if (typeof(KeyParameter).IsInstanceOfType(parameters))
{
KeyParameter p = (KeyParameter)parameters;
SetKey(p.GetKey());
}
else
{
throw new ArgumentException("invalid parameter passed to RC532 init - " + Org.BouncyCastle.Utilities.Platform.GetTypeName(parameters));
}
this.forEncryption = forEncryption;
}
public virtual int ProcessBlock(
byte[] input,
int inOff,
byte[] output,
int outOff)
{
return (forEncryption)
? EncryptBlock(input, inOff, output, outOff)
: DecryptBlock(input, inOff, output, outOff);
}
public virtual void Reset()
{
}
/**
* Re-key the cipher.
*
* @param key 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 = 32/8 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.
//
int[] L = new int[(key.Length + (4 - 1)) / 4];
for (int i = 0; i != key.Length; i++)
{
L[i / 4] += (key[i] & 0xff) << (8 * (i % 4));
}
//
// Phase 2:
// 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*(_noRounds + 1)];
_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, 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;
}
}
/**
* Encrypt the given block starting at the given offset and place
* the result in the provided buffer starting at the given offset.
*
* @param in in byte buffer containing data to encrypt
* @param inOff offset into src buffer
* @param out out buffer where encrypted data is written
* @param outOff offset into out buffer
*/
private int EncryptBlock(
byte[] input,
int inOff,
byte[] outBytes,
int outOff)
{
int A = BytesToWord(input, inOff) + _S[0];
int B = BytesToWord(input, inOff + 4) + _S[1];
for (int i = 1; i <= _noRounds; i++)
{
A = RotateLeft(A ^ B, B) + _S[2*i];
B = RotateLeft(B ^ A, A) + _S[2*i+1];
}
WordToBytes(A, outBytes, outOff);
WordToBytes(B, outBytes, outOff + 4);
return 2 * 4;
}
private int DecryptBlock(
byte[] input,
int inOff,
byte[] outBytes,
int outOff)
{
int A = BytesToWord(input, inOff);
int B = BytesToWord(input, inOff + 4);
for (int i = _noRounds; i >= 1; i--)
{
B = RotateRight(B - _S[2*i+1], A) ^ A;
A = RotateRight(A - _S[2*i], B) ^ B;
}
WordToBytes(A - _S[0], outBytes, outOff);
WordToBytes(B - _S[1], outBytes, outOff + 4);
return 2 * 4;
}
//////////////////////////////////////////////////////////////
//
// PRIVATE Helper Methods
//
//////////////////////////////////////////////////////////////
/**
* Perform a left "spin" of the word. The rotation of the given
* word <em>x</em> is rotated left by <em>y</em> bits.
* Only the <em>lg(32)</em> low-order bits of <em>y</em>
* 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 % 32
*/
private int RotateLeft(int x, int y) {
return ((int) ( (uint) (x << (y & (32-1))) |
((uint) x >> (32 - (y & (32-1)))) )
);
}
/**
* Perform a right "spin" of the word. The rotation of the given
* word <em>x</em> is rotated left by <em>y</em> bits.
* Only the <em>lg(32)</em> low-order bits of <em>y</em>
* 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 % 32
*/
private int RotateRight(int x, int y) {
return ((int) ( ((uint) x >> (y & (32-1))) |
(uint) (x << (32 - (y & (32-1)))) )
);
}
private int BytesToWord(
byte[] src,
int srcOff)
{
return (src[srcOff] & 0xff) | ((src[srcOff + 1] & 0xff) << 8)
| ((src[srcOff + 2] & 0xff) << 16) | ((src[srcOff + 3] & 0xff) << 24);
}
private void WordToBytes(
int word,
byte[] dst,
int dstOff)
{
dst[dstOff] = (byte)word;
dst[dstOff + 1] = (byte)(word >> 8);
dst[dstOff + 2] = (byte)(word >> 16);
dst[dstOff + 3] = (byte)(word >> 24);
}
}
}
#endif