用Ｃ语言实现凯撒密码加密解密，急！

凯撒密码就是简单的加上一个数，'a'+3='d''z'+3='猜旦c' 假设原文全是小写字母，那么 char plain[N]={...}//明文 char cipher[N]={}//密文 int key=3int i=0,tempfor(i=0i<Ni++) {if(plain[i]!=' ') {temp=plain[i]+key-'a'temp=temp%26cipher[i]=temp+'a'} else cipher[i]=plain[i]} 这样就完成了加密，密文数组里面就是对原文加密后的闹信密文，key是穗弯扰密钥。

#include <stdio.h>

#include <string.h>

int main()

{

int i = 0

int len = 0

char ch

char buf[256] = {0}

char nor[26] = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'}

char enc[26] = {'s','u','w','y','a','c','e','g','i','k','m','o','q','r','t','v','x','z'李辩昌,'b','d','f','灶弯h','j','l','n','p'}

printf("Encode or Decode: ")

scanf("%c",&ch)

printf("please input your string: ")

fflush(stdin)

gets(buf)

len = strlen(buf)

switch (ch)

{

case 'e':

case 'E':

for (i=0i<leni++)

{

buf[i] = enc[buf[i] - 'a']

}

break

case 'd':

case 'D':

for (i=0i<leni++)

{

buf[i] = nor[i]

}

break

default:

printf("wrong input!\n")

}

printf("<%s>\n"哪扒,buf)

return 0

}

1.将“We are students.”这个英文词句差链用k=4的凯萨密码翻译成密码

1. 恺撒密码，

作为一种最为古老的对称加密体制，他的基本思想是：

通过把字母移动一定的位数来实现加密和解密。

例如，如果密匙配庆胡是把明文字母的位数向后移动三位，那么明文字母B就变成了密文的E，依次类推，X将变成A,Y变成B,Z变成C，由此可见，位数就是凯撒密码加密和解密的密钥。

如：ZHDUHVWXGHQWV（后移三位）

2. 凯撒密码，

是计算机C语言编程实现加密和解密。挺复杂的。你可以研究一下哦。

2.将凯撒密码（K=7）的加密、解密培拦过程用C语言编程实现

/*

声明：MSVC++6.0环境测试通过

*/

#include<stdio.h>

#include<ctype.h>

#define maxlen 100

#define K 7

char *KaisaEncode(char *str)//加密

{

char *d0

d0=str

for(*str!='\0'str++)

{

if(isupper(*str))

*str=(*str-'A'+K)%26+'A'

else if(islower(*str))

*str=(*str-'a'+K)%26+'a'

else

continue

}

return d0

}

char *KaisaDecode(char *str)//解密

{

char *d0

d0=str

for(*str!='\0'str++)

{

if(isupper(*str))

*str=(*str-'A'-K+26)%26+'A'

else if(islower(*str))

*str=(*str-'a'-K+26)%26+'a'

else

continue

}

return d0

}

int main(void)

{

char s[maxlen]

gets(s)

puts(KaisaEncode(s))

puts(KaisaDecode(s))

return 0

}

3.将凯撒密码X的加密、解密过程用C语言编程实现

(2)kaiser加密算法 具体程序：#include #include char encrypt(char ch,int n)/*加密函数，把字符向右循环移位n*/ { while(ch>='A'&&ch='a'&&ch<='z') { return ('a'+(ch-'a'+n)%26)} return ch} void menu（)/*菜单，1.加密，2.解密，3.暴力破解，密码只能是数字*/ { clrscr()printf("\n=========================================================")printf("\n1.Encrypt the file")printf("\n2.Decrypt the file")printf("\n3.Force decrypt file")printf("\n4.Quit\n")printf("=========================================================\n")printf("Please select a item:")return} main() { int i,nchar ch0,ch1FILE *in,*outchar infile[20],outfile[20]textbackground(BLACK)textcolor(LIGHTGREEN)clrscr()sleep(3)；/*等待3秒*/ menu()ch0=getch()while(ch0!='4') { if(ch0=='1') { clrscr()printf("\nPlease input the infile:")scanf("%s",infile)；/*输入需要加密的文件名*/ if((in=fopen(infile,"r"))==NULL) { printf("Can not open the infile!\n")printf("Press any key to exit!\n")getch()exit(0)} printf("Please input the key:")scanf("%d",&n)；/*输入加密密码*/ printf("Please input the outfile:")scanf("%s",outfile)；/*输入加密后文件的文件名*/ if((out=fopen(outfile,"w"))==NULL) { printf("Can not open the outfile!\n")printf("Press any key to exit!\n")fclose(in)getch()exit(0)} while(!feof(in)）/*加密*/ { fputc(encrypt(fgetc(in),n),out)} printf("\nEncrypt is over!\n")fclose(in)fclose(out)sleep(1)} if(ch0=='2') { clrscr()printf("\nPlease input the infile:")scanf("%s",infile)；/*输入需要解密的文件名*/ if((in=fopen(infile,"r"))==NULL) { printf("Can not open the infile!\n")printf("Press any key to exit!\n")getch()exit(0)} printf("Please input the key:")scanf("%d",&n)；/*输入解密密码（可以为加密时候的密码）*/ n=26-nprintf("Please input the outfile:")scanf("%s",outfile)；/*输入解密后文件的文件名*/ if((out=fopen(outfile,"w"))==NULL) { printf("Can not open the outfile!\n")printf("Press any key to exit!\n")fclose(in)getch()exit(0)} while(!feof(in)) { fputc(encrypt(fgetc(in),n),out)} printf("\nDecrypt is over!\n")fclose(in)fclose(out)sleep(1)} if(ch0=='3') { clrscr()printf("\nPlease input the infile:")scanf("%s",infile)；/*输入需要解密的文件名*/ if((in=fopen(infile,"r"))==NULL) { printf("Can not open the infile!\n")printf("Press any key to exit!\n")getch()exit(0)} printf("Please input the outfile:")scanf("%s",outfile)；/*输入解密后文件的文件名*/ if((out=fopen(outfile,"w"))==NULL) { printf("Can not open the outfile!\n")printf("Press any key to exit!\n")fclose(in)getch()exit(0)} for(i=1i<=25i++)/*暴力破解过程，在察看信息正确后，可以按'Q'或者'q'退出*/ { rewind(in)rewind(out)clrscr()printf("==========================================================\n")printf("The outfile is:\n")printf("==========================================================\n")while(!feof(in)) { ch1=encrypt(fgetc(in),26-i)putch(ch1)fputc(ch1,out)} printf("\n========================================================\n")printf("The current key is: %d \n",i)；/*显示当前破解所用密码*/ printf("Press 'Q' to quit and other key to continue。

\n")printf("==========================================================\n")ch1=getch()if(ch1=='q'||ch1=='Q')/*按'Q'或者'q'时退出*/ { clrscr()printf("\nGood Bye!\n")fclose(in)fclose(out)sleep(3)exit(0)} } printf("\nForce decrypt is over!\n")fclose(in)fclose(out)sleep(1)} menu()ch0=getch()} clrscr()printf("\nGood Bye!\n")sleep(3)}。

4.怎样编写程序：实现恺撒密码加密单词"julus"

用下面程序：新建个txt，放进去任意单词，设置#define N 5中的值，实现字母移位，达到加密目的。

本程序提供解密功能/************************************************************************//* 版权所有：信息工程学院 王明 使用时请注明出处！！ *//* 算法：凯撒密码体制 e799bee5baa6e4b893e5b19e31333264643062 *//************************************************************************/#include #define N 5void jiami(char namea[256]) { FILE *fp_jiami,*fp_file2char cfp_jiami=fopen(namea,"rb")fp_file2=fopen("file2.txt","wb")while(EOF!=(fscanf(fp_jiami,"%c",&c))) { if((c>='A'&&c='a'&&c='A'&&c='a'&&c='a'&&c='A'&&c='a'&&c='A'&&c='a'&&c='A'&&c<='Z')c=c+32 } fprintf(fp_file3,"%c",c)} fclose(fp_file3)fclose(fp_jiemi)}int main(){ char name[256]int nprintf（"输入你要 *** 作的TXT文本："）； gets(name)printf("\n请选择需要进行的 *** 作：\n")printf(" 1：加密 2：解密 \n")printf（"输入你的选择："）； scanf("%d",&n)switch(n) { case 1:{jiami(name)printf("\t加密成功！！\n\n")break} case 2:{jiemi(name)printf("\t解密成功！！\n\n")break} default:{printf（"输入 *** 作不存在！"）；} } return 0}。

5.谁有PYTHON编写的凯撒密码的加密和解密代码

给你写了一个.

def convert(c, key, start = 'a', n = 26):

a = ord(start)

offset = ((ord(c) - a + key)%n)

return chr(a + offset)

def caesarEncode(s, key):

o = ""

for c in s:

if c.islower():

o+= convert(c, key, 'a')

elif c.isupper():

o+= convert(c, key, 'A')

else:

o+= c

return o

def caesarDecode(s, key):

return caesarEncode(s, -key)

if __name__ == '__main__':

key = 3

s = 'Hello world!'

e = caesarEncode(s, key)

d = caesarDecode(e, key)

print e

print d

运行结果：

Khoor zruog!

Hello world!

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