（C语言）简单的文件加密和解密程序

一个简单的文件加密和解密程序

main.c

#include <stdio.h>
#include <stdlib.h>
#include "fun.h"

int main(int argc ,char *argv[])
{
	while(1)
	{	
		


		int cmd=0;
		print_help();
		printf("请输入指令：");
		scanf("%d",&cmd);



		if(cmd==1)
		{
			char dest_file[31]="";
			char src_file[31]="";
			unsigned long file_length=0;
			char  *read=NULL;
			unsigned int password=0;
			//从键盘获取源文件和目的文件名字
			get_file_name(dest_file,src_file);
			
			//从文件中读出内容

			read = read_src_file(&file_length,src_file);
			//获取加密password
			printf("请输入密码：");
			scanf("%u",&password);
			//字符数组加密
			read=file_text_encrypt(read,file_length,password);
			
			//保存文件
			save_file(read,file_length,dest_file);
			

		}
		else if (cmd==2)
		{
			char dest_file[31]="";
			char src_file[31]="";
			unsigned long file_length=0;
			char  *read=NULL;
			unsigned int password=0;
			//从键盘获取源文件和目的文件名字
			get_file_name(dest_file,src_file);
			
			//从文件中读出内容

			read = read_src_file(&file_length,src_file);
			//获取加密password
			printf("请输入密码：");
			scanf("%u",&password);
			//字符数组加密
			read=file_text_decrypt(read,file_length,password);
			
			
			//保存文件
			save_file(read,file_length,dest_file);
			
		}
		else if (cmd==3)
		{
			break;
		}
		else
		{
			printf("输入指令出错！！！\n");
		}

	
	}
	
	return 0;
}

fun.c

#include <stdio.h>
#include <stdlib.h>

void print_help()
{
	printf("********1:加密文件***********\n");
	printf("********2:解密文件***********\n");
	printf("********3:退出程序***********\n");
}


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


char *read_src_file(unsigned long  *file_length,char *src_file_name)
{
	char *data=NULL;
	FILE *fp;

	
	fp=fopen(src_file_name,"r");//只读的方式打开文件
	if(fp==NULL)
	{
		perror("fopen");
		return NULL;
	}
	
	//流指针go尾部
	fseek(fp,0,2);
	//流指针的偏移量
	*file_length = ftell(fp);
	//流指针复位
	rewind(fp);

	//申请空间保存文件
	data=(char *)calloc(1,*file_length);
	if(NULL==data)
	{
		perror("calloc");
		return NULL;
	}

	//一次性读
	fread(data,*file_length,1,fp);

	fclose(fp);
	return data;

}


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

	
}


void save_file(char* text,unsigned long int length,char * file_name)
{	
	char *data=NULL;
	FILE *fp;
	fp=fopen(file_name,"w");
	if(NULL==fp)
	{
		perror("fp");
		return;
	}
	
	//写
	fwrite(text,length,1,fp);

	fclose(fp);
	if(text !=NULL)
	{
		free(text);
		text =NULL;

	}
	return;
}


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

fun.h

#ifndef __FUN_H__
#define __FUN_H__

extern void print_help();
extern void get_file_name(char * dest_file_name,char * src_file_name);
extern char *read_src_file(unsigned long  *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

运行查看

结果
OK！！！