77 lines
1.3 KiB
C++
77 lines
1.3 KiB
C++
// Copyright (C) 2007-2025 EQ2EMulator
|
|
// Licensed under GPL v3
|
|
#include "RC4.h"
|
|
#include <string.h>
|
|
|
|
static bool g_bInitStateInitialized = false;
|
|
static uchar g_byInitState[256];
|
|
|
|
RC4::RC4(int64 nKey)
|
|
{
|
|
if( !g_bInitStateInitialized )
|
|
{
|
|
for(int16 i = 0; i < 256; i++ )
|
|
g_byInitState[i] = i;
|
|
}
|
|
Init(nKey);
|
|
}
|
|
|
|
RC4::~RC4()
|
|
{
|
|
}
|
|
|
|
void RC4::Init(int64 nKey)
|
|
{
|
|
memcpy(m_state, g_byInitState, 256);
|
|
m_x = 0;
|
|
m_y = 0;
|
|
|
|
ulong dwKeyIndex = 0;
|
|
ulong dwStateIndex = 0;
|
|
uchar* pKey = (uchar*)&nKey;
|
|
for(int16 i = 0; i < 256; i++ )
|
|
{
|
|
ulong dwTemp = m_state[i];
|
|
dwStateIndex += pKey[dwKeyIndex] + dwTemp;
|
|
dwStateIndex &= 0xFF;
|
|
m_state[i] = m_state[dwStateIndex];
|
|
m_state[dwStateIndex] = (uchar)dwTemp;
|
|
dwKeyIndex++;
|
|
dwKeyIndex &= 7;
|
|
}
|
|
}
|
|
|
|
// A = m_state[X + 1]
|
|
// B = m_state[Y + A]
|
|
// C ^= m_state[(A + B)]
|
|
|
|
// X = 20
|
|
// Y = ?
|
|
// C = 0
|
|
// m_state[(A + B)] = Cypher Byte
|
|
|
|
void RC4::Cypher(uchar* pBuffer, int32 nLength)
|
|
{
|
|
int32 nOffset = 0;
|
|
uchar byKey1 = m_x;
|
|
uchar byKey2 = m_y;
|
|
if( nLength > 0 )
|
|
{
|
|
do
|
|
{
|
|
byKey1++;
|
|
uchar byKeyVal1 = m_state[byKey1];
|
|
|
|
byKey2 += byKeyVal1;
|
|
uchar byKeyVal2 = m_state[byKey2];
|
|
|
|
m_state[byKey1] = byKeyVal2;
|
|
m_state[byKey2] = byKeyVal1;
|
|
|
|
pBuffer[nOffset++] ^= m_state[(byKeyVal1 + byKeyVal2) & 0xFF];
|
|
} while( nOffset < nLength );
|
|
}
|
|
m_x = byKey1;
|
|
m_y = byKey2;
|
|
}
|