Spencer/PNG_CC
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Pin
2021-10-15 21:17:47 -04:00
parent 6166af2b41
commit 3c6c08429d
5 changed files with 109 additions and 86 deletions
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115
cmd/crc.c
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@@ -1,3 +1,4 @@
#include <endian.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
@@ -66,7 +67,7 @@ void random_data_change(unsigned char *color_data, int width, int length) {
int color_range = 3;
unsigned char temp_color_data[length];
memcpy(temp_color_data, color_data, length);
//memcpy(temp_color_data, color_data, length);
do {
rounds++;
@@ -96,6 +97,7 @@ void random_data_change(unsigned char *color_data, int width, int length) {
unsigned int temp_crc = crc(full_data, check_data_length);
if ((temp_crc >> (8*3)) == 10 ) {
printf("Found in %zu rounds!\n", rounds);
memcpy(color_data, temp_color_data, length);
searching = 0;
}
free(check_data_buff);
@@ -104,8 +106,59 @@ void random_data_change(unsigned char *color_data, int width, int length) {
} while(searching == 1);
}
int change_idat_content(unsigned char *addr, unsigned char *message, int accuracy, unsigned long offset) {
//printf("Starting IDAT Tranform\n");
void build_png_file(struct PNG_FILE_STRUCT *png_file) {
FILE *fp;
fp = fopen("TESTPNG.png", "w");
union{
unsigned char data[sizeof(struct PNG_START_FILE_STRUCT)];
struct PNG_START_FILE_STRUCT png_data;
}start_data;
start_data.png_data = png_file->png_start_data;
// IHDR Data
for(int i = 0; i < sizeof(struct PNG_START_FILE_STRUCT); i++) {
fputc(start_data.data[i], fp);
}
// IDAT Data
for(int i = 0; i < 4; i++) {
fputc(png_file->png_idat_data.idat_length[i], fp);
}
for(int i = 0; i < 4; i++) {
fputc(png_file->png_idat_data.idat_header[i], fp);
}
for(int i = 0; i < be32toh(png_file->png_idat_data.idat_data_length); i++) {
fputc(png_file->png_idat_data.idat_data[i], fp);
}
// Generating CRC
unsigned char full_data[be32toh(png_file->png_idat_data.idat_data_length)+4];
for(int i = 0; i < 4; i++) {
full_data[i] = png_file->png_idat_data.idat_header[i];
}
for(int i = 0; i < be32toh(png_file->png_idat_data.idat_data_length); i++) {
full_data[i+4] = png_file->png_idat_data.idat_data[i];
}
unsigned int int_crc = crc(full_data, be32toh(png_file->png_idat_data.idat_data_length));
unsigned char new_crc[4];
for(int i = 0; i < 4; i++) {
new_crc[i] = int_crc >> (8*(3-i)) & 0xFF;
fputc(new_crc[i], fp);
}
// IEND Data
unsigned char IEND_DATA[12] = { 0x00, 0x00, 0x00, 0x00, 0x49, 0x45, 0x4E, 0x44, 0xAE, 0x42, 0x60, 0x82};
for(int i = 0; i < 12; i++) {
fputc(IEND_DATA[i], fp);
}
fclose(fp);
}
int change_idat_content(unsigned char *addr, struct PNG_FILE_STRUCT *png_file, unsigned char *message, int accuracy, unsigned long offset) {
if(accuracy > 4) {
printf("Warning, accuracy cannot be larger than 4");
return EXIT_FAILURE;
@@ -113,7 +166,7 @@ int change_idat_content(unsigned char *addr, unsigned char *message, int accurac
if(accuracy > 2) {
printf("Notice, this could take a long time...");
}
if(total_idat(addr) < strlen(message)) {
if(total_idat(addr) < strlen((char*)message)) {
printf("Warning, message exceeds IDAT amount");
return EXIT_FAILURE;
}
@@ -121,7 +174,6 @@ int change_idat_content(unsigned char *addr, unsigned char *message, int accurac
int idat_length = check_header_length(addr, offset);
printf("IDAT Length: %d\n", idat_length);
int prop_found = 0;
long size = 1;
size_t idat_byte_length = 0;
unsigned char* idat_data = calloc(size, sizeof(unsigned char));
@@ -134,29 +186,37 @@ int change_idat_content(unsigned char *addr, unsigned char *message, int accurac
idat_byte_length = i;
}
unsigned char temp_idat_data[idat_byte_length];
while(prop_found == 0) {
for(int i = 0; i <= idat_length; i++) {
temp_idat_data[i] = idat_data[i];
}
// Decompressing Data
unsigned char *uncom_data_buff = NULL;
size_t uncom_data_size = 0;
zlib_decompress_data(temp_idat_data, idat_byte_length, &uncom_data_buff, &uncom_data_size);
for(int i = 0; i <= idat_length; i++) {
temp_idat_data[i] = idat_data[i];
}
// Decompressing Data
unsigned char *uncom_data_buff = NULL;
size_t uncom_data_size = 0;
zlib_decompress_data(temp_idat_data, idat_byte_length, &uncom_data_buff, &uncom_data_size);
random_data_change(uncom_data_buff, 16, uncom_data_size);
random_data_change(uncom_data_buff, 16, uncom_data_size);
// Compress Data
unsigned char *com_data_buff;
size_t com_data_size = 0;
zlib_compress_data(uncom_data_buff, uncom_data_size, &com_data_buff, &com_data_size);
free(uncom_data_buff);
png_file->png_idat_data.idat_data = calloc(com_data_size, sizeof(unsigned char));
//printf("Found %d in %d rounds\n", checked_crc ,rounds);
//printf("Full CRC: %08X\n", crcnum);
//printf("Original: %02X\n", idat_data[j]);
//printf("Change offset: %d to hex: %02X\n", j, temp_idat_data[j]);
//addr[offset+8+j] = temp_idat_data[j];
//update_file_crc(addr, offset, crcnum);
prop_found = 1;
// TEMP FIX FOR IDAT SIZE ISSUES
png_file->png_idat_data.idat_length[3] = (unsigned char)com_data_size;
for(size_t i = 0; i < com_data_size; i++) {
png_file->png_idat_data.idat_data[i] = com_data_buff[i];
}
// Build PNG File
build_png_file(png_file);
free(uncom_data_buff);
free(com_data_buff);
free(idat_data);
free(png_file->png_idat_data.idat_data);
return 0;
}
@@ -166,8 +226,7 @@ int main() {
FILE *fp;
size_t i = 0;
unsigned long offset = 0;
struct PNG_START_FILE_STRUCT png_start_file_data;
struct PNG_IDAT_FILE_STRUCT png_idat_file_data;
struct PNG_FILE_STRUCT png_file_data;
unsigned char *message = malloc(sizeof(char));
message[0] = '\0';
@@ -185,15 +244,15 @@ int main() {
unsigned char *file_data = file_to_char_array(fp, &i);
fclose(fp);
populate_start_png(file_data, &png_start_file_data);
populate_start_png(file_data, &png_file_data.png_start_data);
offset = first_idat(file_data);
printf("Off: %ld\n", offset);
populate_idat_png(file_data, &png_idat_file_data, offset);
populate_idat_png(file_data, &png_file_data.png_idat_data, offset);
change_idat_content(file_data, &png_file_data, message, 1, offset);
change_idat_content(file_data, message, 1, offset);
free(file_data);
free(message);
//create_cc_file(file_data, i);
}