一 文件加密器

1.1 原理的分析

1.2 代码

fun.h文件

#ifndef __FUN_H__
#define __FUN_H__
extern void help(void);
extern void get_file_name(char *src_file_name, char *dest_file_name);
extern char *read_src_file(unsigned long int *file_length,char *src_file_name);
extern char *file_text_encrypt(char *src_file_text,unsigned long int length,unsigned int password);
extern void save_file(char *text,unsigned long int length,char *file_name);
extern char *file_text_decrypt(char *src_file_text,unsigned long int length,unsigned int password);
#endif

fun.c文件

#include <stdio.h>
#include <stdlib.h>
void help(void)
{
          
   
	printf("********1：加密文件********
");
	printf("********2：解密文件********
");
	printf("********3：退出程序********
");
}

void get_file_name(char *src_file_name, char *dest_file_name)
{
          
   
	printf("请输入源文件名称（30个字符）：");
	scanf("%s",src_file_name);
	printf("请输入目的文件名称（30个字符）：");
	scanf("%s",dest_file_name);
	return;
}

char *read_src_file(unsigned long int *file_length,char *src_file_name)
{
          
   
	FILE* fp = NULL;
	fp = fopen(src_file_name,"r");
	if(fp == NULL)
	{
          
   
		perror("fopen");
		return NULL;
	}
	fseek(fp,0,2);
	*file_length = ftell(fp);
	fseek(fp,0,SEEK_SET);
	char *file_text = NULL;
	file_text = (char*)calloc(1,*file_length);
	if(file_text == NULL)
	{
          
   
		perror("申请堆栈空间失败");
		return NULL;
	}
	fread(file_text,*file_length,1,fp);
	fclose(fp);
	return file_text;
}

char *file_text_encrypt(char *src_file_text,unsigned long int length,unsigned int password)
{
          
   
	unsigned long int n = 0;
	for(n=0;n<length;n++)
	{
          
   
		src_file_text[n] += password;
	}
	return src_file_text;
}

char *file_text_decrypt(char *src_file_text,unsigned long int length,unsigned int password)
{
          
   
	unsigned long int n = 0;
	for(n=0;n<length;n++)
	{
          
   
		src_file_text[n] -= password;
	}
	return src_file_text;
}

void save_file(char *text,unsigned long int length,char *file_name)
{
          
   
	FILE* fp = NULL;
	fp = fopen(file_name,"w");
	if(fp == NULL)
	{
          
   
		perror("fopen");
		return;
	}
	fwrite(text,length,1,fp);
	fclose(fp);
	if(text != NULL)
	{
          
   
		free(text);
		text = NULL;
	}
	printf("保存文件成功
");
	return;
}

main.c文件

#include <stdio.h>
#include "fun.h"
int main(int argc,char *argv[])
{
          
   	
	while(1)
	{
          
   
		int cmd = 0;
		help();
		printf("请输入选项:");
		scanf("%d",&cmd);
		if(cmd == 1)
		{
          
   
			char src_file[31] = "";
			char dest_file[31] = "";
			//1. 获取源文件和目的文件名
			get_file_name(src_file,dest_file);
			//2. 获取源文件的文件内容
			unsigned long int length = 0;
			char *raw_file_text = NULL;
			raw_file_text = read_src_file(&length,src_file);
			//3. 获取用户输入的密码
			unsigned int encrypt_password = 0;
			printf("请输入用于加密的密码：");
			scanf("%u",&encrypt_password);
			//4. 对文件内容加密
			char *encrypt_file_text = NULL;
			encrypt_file_text = file_text_encrypt(raw_file_text,length,encrypt_password);
			//5. 将加密的文件内容保存到文件中
			save_file(encrypt_file_text,length,dest_file);
		}
		else if(cmd == 2)
		{
          
   
			char src_file[31] = "";
			char dest_file[31] = "";
			//1. 获取源文件和目的文件名
			get_file_name(src_file,dest_file);
			//2. 获取源文件的文件内容
			unsigned long int length = 0;
			char *encrypt_file_text = NULL;
			encrypt_file_text = read_src_file(&length,src_file);
			//3. 获取用户输入的密码
			unsigned int decrypt_password = 0;
			printf("请输入用于解密的密码：");
			scanf("%u",&decrypt_password);
			//4. 对文件内容解密
			char *decrypt_file_text = NULL;
			decrypt_file_text = file_text_decrypt(encrypt_file_text,length,decrypt_password);
			//5. 将加密的文件内容保存到文件中
			save_file(decrypt_file_text,length,dest_file);
		}
		else if(cmd == 3)
			break;
		else
			printf("请输入一个正确的选项
");
	}
	return 0;
}