Unity防破解——加密Dll与Key保护

#include 
#include <string.h>
#include 
#include "xxtea.h"

#define SIZE 1024*1024*10
void main() //命令行参数
{
    FILE *infp = 0;//判断命令行是否正确
    if((infp=fopen("Assembly-CSharp.dll","rb"))==NULL)
    {
        printf("Assembly-CSharp.dll Read Error\n");//打开操作不成功
        return;//结束程序的执行
    }

    //char buffer[SIZE];
    char* buffer = (char*)malloc(sizeof(char)*SIZE);
    memset(buffer,0,sizeof(char)*SIZE);

    int rc = 0;
    int total_len = 0;

    total_len = fread(buffer , sizeof(unsigned char) , SIZE , infp);
    printf("Read Assembly-CSharp Successfully and total_len : %d \n" , total_len);

    //加密DLL
    size_t len;
    char* key = "123456";
    char *encrypt_data = xxtea_encrypt(buffer,total_len, key, &len);

    printf("Encrypt Dll Successfully and len : %d\n" , len);

    //写Dll
    FILE* outfp = 0;
    if((outfp=fopen("Assembly-CSharp_encrypt.dll","wb+"))==NULL)
    {
        printf("Assembly-CSharp_encrypt.dll Read Error\n");//打开操作不成功
        return;//结束程序的执行
    }

    int rstCount = fwrite(encrypt_data , sizeof(unsigned char) , len , outfp);
    
    fflush(outfp);

    printf("Write len : %d\n", rstCount);

    fclose(infp);
    fclose(outfp);

    free(buffer);
    free(encrypt_data);
}

MonoImage *
mono_image_open_from_data_with_name (char *data, guint32 data_len, gboolean need_copy, MonoImageOpenStatus *status, gboolean refonly, const char *name)
{
    
    if(strstr(name ,"Assembly-CSharp.dll")){
        g_message("mono: === Start Decrypt Dll ==========\n");
        char key = "123456";
        size_t len;
        char* decryptData = decrypt(data , key);//换成对应的解密函数
        int i = 0;
        for ( i = 0; i i)
        {
          data[i] = decryptData[i];
        }
        g_free(decryptData);
        g_message("mono: === End Decrypt Dll ========== \n");
    }

    ........

    return register_image (image);
}

#include 
#include 
#include 
#include <string.h>
 
 
/* 32-bit ELF base types. */
typedef unsigned int Elf32_Addr;
typedef unsigned short Elf32_Half;
typedef unsigned int Elf32_Off;
typedef signed int Elf32_Sword;
typedef unsigned int Elf32_Word;
 
 
 
 
#define EI_NIDENT 16
 
/*
 * ELF header.
 */
 
typedef struct {
  unsigned char  e_ident[EI_NIDENT];  /* File identification. */
  Elf32_Half  e_type;    /* File type. */
  Elf32_Half  e_machine;  /* Machine architecture. */
  Elf32_Word  e_version;  /* ELF format version. */
  Elf32_Addr  e_entry;  /* Entry point. 4 byte int  */
  Elf32_Off  e_phoff;  /* Program header file offset. */
  Elf32_Off  e_shoff;  /* Section header file offset. 4 byte int */
  Elf32_Word  e_flags;  /* Architecture-specific flags. */
  Elf32_Half  e_ehsize;  /* Size of ELF header in bytes. */
  Elf32_Half  e_phentsize;  /* Size of program header entry. */
  Elf32_Half  e_phnum;  /* Number of program header entries. */
  Elf32_Half  e_shentsize;  /* Size of section header entry. */
  Elf32_Half  e_shnum;  /* Number of section header entries. */
  Elf32_Half  e_shstrndx;  /* Section name strings section. */
} Elf32_Ehdr;
 
/*
 * Section header.
 */
 
typedef struct {
  Elf32_Word  sh_name;  /* Section name (index into the
             section header string table). */
  Elf32_Word  sh_type;  /* Section type. */
  Elf32_Word  sh_flags; /* Section flags. */
  Elf32_Addr  sh_addr;  /* Address in memory image. */
  Elf32_Off sh_offset;  /* Offset in file. */
  Elf32_Word  sh_size;  /* Size in bytes. */
  Elf32_Word  sh_link;  /* Index of a related section. */
  Elf32_Word  sh_info;  /* Depends on section type. */
  Elf32_Word  sh_addralign; /* Alignment in bytes. */
  Elf32_Word  sh_entsize; /* Size of each entry in section. */
} Elf32_Shdr;
 
 
int main(int argc, char** argv){

  Elf32_Ehdr ehdr;
  Elf32_Ehdr _ehdr;

  unsigned int key = xxxx;//决定key的因子
  int i;
  int fd;
  
  if(argc <2){
    puts("Input .so file");
    return -1;
  }
  
  fd = open(argv[1], O_RDWR);
  if(fd <0){
    printf("open %s failed\n", argv[1]);
    goto _error;
  }
  
  //读取ELF文件头（mono.so 52个字节）
  if(read(fd, &ehdr, sizeof(Elf32_Ehdr)) != sizeof(Elf32_Ehdr)){
    puts("Read ELF header error");
    goto _error;
  }
  
  ehdr.e_shoff = key;
  //覆盖新ELF文件头
  lseek(fd, 0, SEEK_SET);
  if(write(fd, &ehdr, sizeof(Elf32_Ehdr)) != sizeof(Elf32_Ehdr)){
    puts("Write ELFhead to .so failed");
    goto _error;
  }
  
  lseek(fd, 0, SEEK_SET);
  read(fd, &_ehdr, sizeof(Elf32_Ehdr));
  printf("Write Key : %d \n", _ehdr.e_shoff);

  puts("Completed");
_error:
  close(fd);
  return 0;
}

//SO---------------加密----------------------
 
#include 
#include 
#include 
 
unsigned int encrypt_key = 456987;


void mono_trace_free_tree() __attribute__((constructor));
unsigned long getLibAddr();


int getKey();

int getKey(){
  return luta_encrypt_key;
}

void mono_trace_free_tree(){

  g_message("mono:============= print Elf Start =============\n");
  unsigned long base;
  Elf32_Ehdr *ehdr;

  base = getLibAddr(); 

  ehdr = (Elf32_Ehdr *)base;
  unsigned int temp_key = ehdr->e_shoff;
 encrypt_key = fun(temp_key);

  g_message("mono: Find luta_encrypt_key = %d\n",encrypt_key);
  g_message("mono: ============= print Elf End =============\n");


}

unsigned long getLibAddr(){
  unsigned long ret = 0;
  char name[] = "libmono.so";
  char buf[4096], *temp;
  int pid;
  FILE *fp;
  pid = getpid();
  sprintf(buf, "/proc/%d/maps", pid);
  fp = fopen(buf, "r");
  if(fp == NULL)
  {
    g_message("mono: open failed");
    goto _error;
  }
  while(fgets(buf, sizeof(buf), fp)){
    if(strstr(buf, name)){
      temp = strtok(buf, "-");
      ret = strtoul(temp, NULL, 16);
      break;
    }
  }
_error:
  fclose(fp);
  return ret;
}
//SO---------------加密----------------------