cpp1.cpp

古典密码学的经典例子。通过该程序可以实现古典密码学的加密过程

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

void main()
{
	FILE *fi;
	FILE *fo;
	int ch,c,a,m,tc;
	fi = fopen("license.txt","rb");
	fo = fopen("secret.txt","wb");
	int cc[256]={0};
	printf("请输入移位量：\n");
	scanf("%d",&m);
	m=m%26;
	while((ch=getc(fi))&&(ch!=EOF))
	{
		if(ch>=65&&ch<=90||ch>=97&&ch<=122)
		{
			if (ch>='a')
			{
				tc=((ch-'a'+m)%26)+'a';
				putc(tc,fo);
			}
			else
			{
				tc=((ch-'A'+m)%26)+'A';
				putc(tc,fo);
			}
			cc[ch]++;
			a++;
		}
		else putc(ch,fo);
	}
	printf("文件已加密，密文存储在secret.txt文件中\n");
	printf("原文中，各字母的个数为\n");
	printf("字母        个数\n");
	for(c=65;c<123;c++)
	{	
		if(c<=90||c>=97)
		{
			printf("arc=%c        %d\n",c,cc[c]);
		}
	}

	fclose(fi);

}