实验一古典密码-vigernere算法

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1、实验一古典密码-Vigenere算法姓名:班级：学号:一、实验目的1、理解简单加密算法的原理；2、掌握Vigenere密码的原理，完成Vigenere密码加解密程序的编写；3、通过实验，加深对古典密码体制的了解，掌握对字符进行灵活处理的方法。二，实验要求根据Vigenere密码的原理编写程序，对输入的符号串能够根据设置的密钥分別正确实现Vigenere加密和解密功能。三，实验过程及内容源程序#include"stdio.h”#include"string.h"#defineBUF_MAX100staticintsquare[27][27];//密钥统一转换力大写字母voidUpp

2、erKey(charkey[]){intkey_length=strlen(key);for(inti=0;i='a'&&key[i]<='z'){key[i]-=32;}}}//Vigenere加密voidVigenereEncrypt(charword门，charkey门){chartext[BUF_MAX];intkey_length=strlen(key);intwordjength=strlen(word);inti，j，k;for(i=0;i

3、dlij>='a'&&wordlij<=’z’){k=wordlij-'a';k=(k+key[j]-.A.)%26;text[i]=k+'a';}elseif(wordlij>='A*&&wordlij<='Z'){k=wordlij-'A';k=(k+keyljj-'A')%26;text[i]=k+’A';}else{text[i]=word[i];}}text[i]=W;printf("Encryptstring:");puts(text);}//Vigenere解密voidVigenereDecript(charen_word[],charkey门){charword[

4、BUF_MAX];intkey_length=strlen(key);intwordjength=strlen(en一word);inti，j，k;for(i=0;i='a'&&en_word[i]<=’z’)k=enlworduj--a-;1<=(k-(keyuj->•)+26)％26;words=k+-a-;}elseif(enlwordsv=->enlword【一】<=N){k=enlworduj->•;=(k-(keyE>)+26)％26;words=k+->;}else{wor

5、dE=slwordlij;}}wo3.【i】ll-;Printfc-Decryptstring::)；puts(word)；}intmain(void){charkey【BUFIMAXLch;charstr【BUFIMAXl={-Q};intij;//^Bnsvigenere^®for(i=1;i<27;T+){fora=l;j<27;j++){square【i】E=2+i+j;if(square【i】s>90){squaressHsquare【islI26;printf("VigenereCode");printf(•’l:Encryption");printf(

6、"2:Decryption");printf(.’Pleaseinputyourchoose:"for(i=0;;i++){scanf(H%du,&j);if0=1){VigenereEncrypt(str,key);break;}elseif(j==2){VigenereDecript(str,key);break;}else{printf("输入错误，重新输入：n);fflush(stdin);printf("Pleaseinputastring:");i=0;do{scanf("%c",&ch);str[i++]=ch;}while(ch!=V&&i

7、AX);printf("Pleaseinputthekey:’’)；scanf("%s",key);UpperKey(key);return0;程序运行结果:Vigenere加密Xj^JigenereCode:Encryptionyourchoose：1astring:hellowordthekey：english2：DecryptionPleaseinputPleaseinputPleaseinputEncryptstring：IrrwwdsejProcessexitedwit