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/* zenutils - Utilities for working with creative firmwares.
* Copyright 2007 (c) Rasmus Ry <rasmus.ry{at}gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "updater.h"
#include <file.h>
#include <pe.h>
#include <utils.h>
const char* zen::find_firmware_key(const byte* buffer, size_t len)
{
char szkey1[] = "34d1";
size_t cchkey1 = strlen(szkey1);
char szkey2[] = "TbnCboEbn";
size_t cchkey2 = strlen(szkey2);
for (int i = 0; i < static_cast<int>(len); i++)
{
if (len >= cchkey1)
{
if (!strncmp((char*)&buffer[i], szkey1, cchkey1))
{
return (const char*)&buffer[i];
}
}
if (len >= cchkey2)
{
if (!strncmp((char*)&buffer[i], szkey2, cchkey2))
{
return (const char*)&buffer[i];
}
}
}
return "";
}
dword zen::find_firmware_offset(byte* buffer, size_t len)
{
for (dword i = 0; i < static_cast<dword>(len); i += 4)
{
dword size = *(dword*)&buffer[i];
if (size != 0
&& buffer[i + 4] != 0
&& buffer[i + 4 + 1] != 0
&& buffer[i + 4 + 2] != 0
&& buffer[i + 4 + 3] != 0)
{
return i;
}
if(i > 0xFF) /* Arbitrary guess */
return 0;
}
return 0;
}
bool zen::find_firmware_archive(const std::string& filename, dword& va, dword& pa)
{
shared::pe_file pef;
if (!pef.read(filename))
{
return false;
}
shared::section_info data_section;
if (!pef.find_section(".data", data_section))
{
return false;
}
shared::bytes buffer;
if (!shared::read_file(filename, buffer, data_section.raw_address,
data_section.raw_size))
{
return false;
}
dword offset = find_firmware_offset(&buffer[0], buffer.size());
if (!offset)
{
return false;
}
va = data_section.virtual_address + offset;
pa = data_section.raw_address + offset;
return true;
}
bool zen::crypt_firmware(const char* key, byte* buffer, size_t len)
{
#if 1
char key_cpy[255];
unsigned int i;
unsigned int tmp = 0;
int key_length = strlen(key);
for(i=0; i < strlen(key); i++)
key_cpy[i] = key[i] - 1;
for(i=0; i < len; i++)
{
buffer[i] ^= key_cpy[tmp] | 0x80;
tmp = (tmp + 1) % key_length;
}
return true;
#else
/* Determine if the key length is dword aligned. */
int keylen = strlen(key);
int keylen_rem = keylen % sizeof(dword);
/* Determine how many times the key must be repeated to be dword aligned. */
int keycycle = keylen_rem ? (sizeof(dword) / keylen_rem) : 1;
int keyscount = (keylen * keycycle) / sizeof(dword);
/* Allocate a buffer to hold the key as an array of dwords. */
dword* keys = new dword[keyscount];
/* Copy the key into the key array, whilst mutating it. */
for (int i = 0; i < keyscount; i++)
{
dword val;
int keyoffset = (i * sizeof(dword)) % keylen;
if ((keyoffset+sizeof(dword)) < keylen)
{
val = *(dword*)&key[keyoffset];
}
else
{
val = key[keyoffset]
| (key[(keyoffset + 1) % keylen] << 8)
| (key[(keyoffset + 2) % keylen] << 16)
| (key[(keyoffset + 3) % keylen] << 24);
}
keys[i] = (val - 0x01010101) | 0x80808080;
}
/* Determine the number of dwords in the buffer. */
int len_div = len / sizeof(dword);
/* Decrypt all dwords of the buffer. */
for (int i = 0; i < len_div; i++)
{
((dword*)buffer)[i] ^= keys[i % keyscount];
}
/* Determine the remaining number of bytes in the buffer. */
int len_rem = len % sizeof(dword);
/* Decrypt the remaining number of bytes in the buffer. */
for (int i = len_div * sizeof(dword); i < len; i++)
{
buffer[i] ^= ((key[i % keylen] - 0x01) | 0x80);
}
return true;
#endif
}
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