算法很简单，汇编代码如下

int _declspec(naked) _cdecl HSEncLog(unsigned char *pOutBuf, int nOutlen, unsigned char *pInBuf, int nInlen, int key)
{
    _asm
    {
		mov     edx, dword ptr [esp+4]
		push    ebx
		test    edx, edx
		push    esi
		je L054
		mov     esi, dword ptr [esp+14h]
		test    esi, esi
		je L054
		mov     ecx, dword ptr [esp+10h]
		test    ecx, ecx
		jle L054
		mov     ebx, dword ptr [esp+18h]
		test    ebx, ebx
		jle L054
		push    ebp
		mov     ebp, ecx
		push    edi
		xor     eax, eax
		mov     edi, edx
		shr     ecx, 2
		rep     stos dword ptr es:[edi]
		mov     ecx, ebp
		and     ecx, 3
		test    ebx, ebx
		rep     stos byte ptr es:[edi]
		jle L048
		mov     ecx, dword ptr [esp+24h]
		sub     esi, edx
		mov     edi, ebx
L029:
		mov     al, byte ptr [esi+edx]
		xor     ebx, ebx
		mov     bl, ch
		xor     al, bl
		mov     byte ptr [edx], al
		movzx   ax, al
		add     eax, ecx
		lea     ecx, dword ptr [eax+eax*2]
		shl     ecx, 4
		sub     ecx, eax
		lea     ecx, dword ptr [ecx+ecx*2]
		lea     ecx, dword ptr [ecx+ecx*4]
		lea     ecx, dword ptr [ecx+ecx*8]
		lea     eax, dword ptr [eax+ecx*2]
		mov     ecx, 58BFh
		sub     ecx, eax
		inc     edx
		dec     edi
		jnz L029
L048:
		pop     edi
		pop     ebp
		pop     esi
		xor     eax, eax
		pop     ebx
		retn
L054:
		pop     esi
		or      eax, 0FFFFFFFFh
		pop     ebx
		retn
    }
}

[招生]科锐逆向工程师培训(2024年11月15日实地，远程教学同时开班, 第51期)