Subversion Repositories filter_foundry

/*

    This file is part of "Filter Foundry", a filter plugin for Adobe Photoshop

    Copyright (C) 2003-2009 Toby Thain, toby@telegraphics.com.au

    Copyright (C) 2018-2021 Daniel Marschall, ViaThinkSoft

    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 <stddef.h>

#include <stdint.h>

#include "ff.h"

// this value will be manipulated during the building of each individual filter (see make_win.c)

const volatile uint32_t cObfuscV4Seed = 0x52830517;

int rand_msvcc(unsigned int* seed) {

        *seed = *seed * 214013L + 2531011L;

        return (*seed >> 16) & 0x7fff; /* Scale between 0 and RAND_MAX */

}

int rand_openwatcom(unsigned int* seed) {

        // https://github.com/open-watcom/open-watcom-v2/blob/master/bld/clib/math/c/rand.c

        *seed = *seed * 1103515245L + 12345L;

        return (*seed >> 16) & 0x7fff; /* Scale between 0 and RAND_MAX */

}

void xorshift(unsigned char** p, uint32_t* x32, size_t num) {

        size_t i;

        unsigned char* x = *p;

        for (i = 0; i < num; i++) {

                // https://de.wikipedia.org/wiki/Xorshift

                *x32 ^= *x32 << 13;

                *x32 ^= *x32 >> 17;

                *x32 ^= *x32 << 5;

                *x++ ^= *x32;

        }

        *p = x;

}

int obfuscation_version(PARM_T* pparm) {

        uint32_t obfusc_info = pparm->unknown2;

        if (obfusc_info == 0x00000000) { // 00 00 00 00

                // Photoshop FilterFactory default initialization

                // (no obfuscation)

                return 0;

        }

        else if (obfusc_info == 0x00000001) { // 01 00 00 00

                // Premiere FilterFactory default initialization

                // (no obfuscation)

                return 0;

        }

        else if (obfusc_info == 0x90E364A3) { // A3 64 E3 90

                // Version 1 obfuscation (Filter Foundry 1.4b8,9,10)

                return 1;

        }

        else if (obfusc_info == 0xE2CFCA34) { // 34 CA CF E2

                // Version 2 obfuscation (Filter Foundry 1.7b1)

                return 2;

        }

        else if ((obfusc_info >= 4) && (obfusc_info <= 0xFF)) { // xx 00 00 00

                // Version 4 obfuscation (Filter Foundry 1.7.0.7)

                // Version 5 obfuscation (Filter Foundry 1.7.0.8)

                // Future: Version 6, 7, 8, ... 255

                return obfusc_info;

        }

        else {

                // Version 3 obfuscation (Filter Foundry 1.7.0.5)

                // obfusc_info is the srand() seed and is equal to the time(0) build timestamp

                return 3;

        }

}

uint32_t crc32b(char *data, int nLength) {

        int i, j, k;

        uint32_t crc, mask;

        char byte;

        i = 0;

        crc = 0xFFFFFFFF;

        for(k=0;k<nLength;k++) {

                byte = data[k];

                crc = crc ^ byte;

                for (j = 7; j >= 0; j--) {

                        mask = (-1) * (crc & 1);

                        crc = (crc >> 1) ^ (0xEDB88320 & mask);

                }

                i++;

        }

        return ~crc;

}

uint32_t obfusc(PARM_T* pparm) {

        // Windows:   Version 5 obfuscation (Introduced in Filter Foundry 1.7.0.8)

        // Macintosh: Version 4 obfuscation (Introduced in Filter Foundry 1.7.0.7)

        unsigned char* p;

        size_t size, seed_position;

        uint32_t seed, initial_seed;

        uint32_t obfusc_version;

#ifdef MAC_ENV

        // For Mac, we use obfuscation version 4, because the placing the seed into the produced executable code is not implemented in Mac!

        // (It needs to be implemented in make_mac.c)

        initial_seed = OBFUSC_V4_DEFAULT_SEED;

        obfusc_version = 4;

#else

        // In obfuscation version 5, the seed is also the checksum. It will be verified at deobfusc()!

        pparm->unknown2 = 0; // make sure crc32b matches always

        initial_seed = crc32b((char*)pparm,sizeof(PARM_T));

        obfusc_version = 5;

#endif

        seed_position = offsetof(PARM_T, unknown2);

        size = sizeof(PARM_T);

        seed = initial_seed;

        if (obfusc_version == 5) {

                // make v4 and v5 intentionally incompatible to avoid a downgrade-attack

                seed ^= 0xFFFFFFFF;

        }

        p = (unsigned char*)pparm;

        xorshift(&p, &seed, seed_position);

        *((uint32_t*)p) = obfusc_version;

        p += 4;

        xorshift(&p, &seed, size - seed_position - 4);

        return initial_seed;

}

void deobfusc(PARM_T* pparm) {

        uint32_t obfusc_version;

        size_t size = sizeof(PARM_T);

        obfusc_version = obfuscation_version(pparm);

        switch (obfusc_version) {

                case 0:

                        // no obfuscation

                        return;

                case 1: {

                        // Version 1 obfuscation (Filter Foundry 1.4b8,9,10)

                        // Filter built with VC++ (official release by Toby Thain)

                        unsigned char* p;

                        size_t i;

                        uint32_t seed;

                        seed = 0xdc43df3c;

                        for (i = size, p = (unsigned char*)pparm; i--;) {

                                *p++ ^= rand_msvcc(&seed);

                        }

                        break;

                }

                case 2: {

                        // Version 2 obfuscation (Filter Foundry 1.7b1)

                        // Compiler independent

                        unsigned char* p;

                        size_t i;

                        uint32_t seed;

                        seed = 0x95d4a68f;

                        for (i = size, p = (unsigned char*)pparm; i--;) {

                                seed ^= seed << 13;

                                seed ^= seed >> 17;

                                seed ^= seed << 5;

                                *p++ ^= seed;

                        }

                        break;

                }

                case 3: {

                        // Version 3 obfuscation (Filter Foundry 1.7.0.5)

                        // NO loading of other implementation supported, but that doesn't matter since

                        // obfuscation and protection is combined in Filter Factory >= 1.7.0.5.

                        // Using rand() is more secure, because it differs from compiler to compiler, so

                        // it is harder to read a protected 8BF plugin.

                        // Note that rand() in combination with srand() is deterministic, so it is safe

                        // to use it: https://stackoverflow.com/questions/55438293/does-rand-function-in-c-follows-non-determinstc-algorithm

                        // Note: 32-Bit FF is built using OpenWatcom (to support Win95), while 64-Bit FF is built using Microsoft Visual C++

                        unsigned char* p;

                        size_t i;

                        uint32_t seed;

                        size_t seed_position;

                        seed = pparm->unknown2;

                        seed_position = offsetof(PARM_T, unknown2); // = offsetof(PARM_T_PREMIERE, unknown1)

                        srand(seed);

                        p = (unsigned char*)pparm;

                        for (i = 0; i < seed_position; i++) *p++ ^= rand();

                        *((uint32_t*)p) = 0; // here was the seed. Fill it with 0x00000000

                        p += 4;

                        for (i = 0; i < size - seed_position - 4; i++) *p++ ^= rand();

                        break;

                }

                case 4:

                case 5: {

                        // Version 4 obfuscation (Filter Foundry 1.7.0.7)

                        // Version 5 obfuscation (Filter Foundry 1.7.0.8)

                        // Not compiler dependent, but individual for each build

                        // It is important that this code works for both x86 and x64 indepdently from the used compiler,

                        // otherwise, the cross-make x86/x64 won't work!

                        // Version 5 contains a seed requirement (checksum).

                        unsigned char* p;

                        size_t seed_position;

                        uint32_t seed, initial_seed;

                        initial_seed = cObfuscV4Seed; // this value will be manipulated during the building of each individual filter (see make_win.c)

                        seed = initial_seed;

                        seed_position = offsetof(PARM_T, unknown2); // = offsetof(PARM_T_PREMIERE, unknown1)

                        if (obfusc_version == 5) {

                                // make v4 and v5 intentionally incompatible to avoid a downgrade-attack

                                seed ^= 0xFFFFFFFF;

                        }

                        p = (unsigned char*)pparm;

                        xorshift(&p, &seed, seed_position);

                        p += 4; // obfusc info == 4

                        xorshift(&p, &seed, size - seed_position - 4);

                        if (obfusc_version == 5) {

                                pparm->unknown2 = 0; // make sure crc32b matches always

                                if (crc32b((char*)pparm,sizeof(PARM_T)) != initial_seed) {

                                        // Integrity check failed!

                                        memset(pparm, 0, sizeof(PARM_T)); // invalidate everything

                                }

                        }

                        break;

                }

                default: {

                        // Obfuscation version unexpected!

                        memset(pparm, 0, sizeof(PARM_T)); // invalidate everything

                        // If "return" is present: Calling function will receive an invalid cbSize value, hence showing "incompatible obfuscation"

                        // If "return" is not present: Then the code below will set a correct cbSize and iProtect flag if obfusc_version>=3, which will raise the error "filter is protected"

                        return;

                }

        }

        if ((pparm->cbSize != PARM_SIZE) &&

                //(pparm->cbSize != PARM_SIZE_PREMIERE) &&

                (pparm->cbSize != PARM_SIG_MAC)) {

                memset(pparm, 0, sizeof(PARM_T)); // invalidate everything

        }

        if (obfusc_version >= 3) {

                // Filter Foundry >= 1.7.0.5 builds combines obfuscation and protection

                // when a standalone filter is built. Theoretically, you can un-protect a

                // plugin, even if it is obfuscated, just by bit-flipping the LSB of byte 0x164.

                // Therefore, we enforce that the plugin is protected!

                pparm->iProtected = 1;

                // Furthermore, if obfuscation 3+ failed (since the seed is individual for each 8BF file),

                // we still want that load_*.c is able to detect pparm->iProtected instead

                // of throwing the error "Incompatible obfuscation".

                pparm->cbSize = PARM_SIZE;

        }

        if (obfusc_version >= 1) {

                // information was lost due to obfuscation. Make sure it is zero.

                pparm->unknown2 = 0;

        }

}