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플레이페어 암화화란플레이페어 암호화는 영국의 물리학자 휘트스톤과 영국의 수학자 플레이페어가 함께 만든 함호화 방식입니다.
휘트스톤이 죽은다음 발표를 하게되어 이 암호화 방식은 플레이페어란 이름을 붙이게 되었습니다.
순서
1. 암호화키 중복문자 제거
EX) 암호화키(ASSASSINATOR) -> (ASINTOR)
2. 암호화키 5x5 테이블에 삽입
A |
S |
I |
N |
T |
O |
R |
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3. 빈테이블에 알파벳 A~Z까지 삽입
단 I/J or Q/Z 같은 자리에 넣어줘야 ㅎ
A |
S |
I |
N |
T |
O |
R |
B |
C |
D |
E |
F |
G |
H |
J |
K |
L |
M |
P |
Q/Z |
U |
V |
W |
X |
Y |
규칙
1. 문장을 2글자씩 쪼개기(한쌍의 문자가 같거나 마지막에 하나남은 문자에 X추가)
규칙1. 암호화 하려는 두 문자가 서로다른 행과 다른 열에 존재할 경우
규칙2. 두 문자가 같은 열에 있는 경우
규칙3. 두 문자가 같은 행에 있는 경우
c언어 코드
#include<stdio.h>
#include<stdlib.h>
void MakeCypherTable(char table[][5]);
void Plain2Cypher(char table[][5]);
char Encrypt_DifferRowNColumn(char table[][5],int i,int j);
char Encrypt_SameRow(char table[][5],int i,int j);
char Encrypt_SameColumn(char table[][5], int i,int j);
void Cypher2Plain(char table[][5]);
char Decrypt_DifferRowNColumn(char table[][5],int i,int j);
char Decrypt_SameRow(char table[][5],int i,int j);
char Decrypt_SameColumn(char table[][5],int i,int j);
int flag=0;
main()
{
int select=0;
char table[5][5];
while(1)
{
printf("input num (1.start/0.end):");
scanf("%d",&select);
getchar();
if(select==0)
{
return 0;
}
else if(select==1)
{
MakeCypherTable(table);
Plain2Cypher(table);
Cypher2Plain(table);
}
}
}
void MakeCypherTable(char table[][5])
{
char alph[]= "ABCDEFGHIJKLMNOPQRSTUVWXY";
char keystring[30];
int count=0,alphnum=0;
int i,j,k,keylen,keycheck,alphcheck;
printf("input key string:");
gets(keystring);
//----key overlap
for(i=0;i<(strlen(keystring))-1;i++)
{
for(j=i+1;j<strlen(keystring);j++)
{
if(keystring[i]==keystring[j])
{
keycheck=j;
for(k=keycheck;k<(strlen(keystring)-1);k++)
{
keystring[k]=keystring[k+1];
}
keystring[strlen(keystring)-1]='\0';
j=j-1;
}
}
}
printf("keystring:%s\n",keystring);
for(i=0;i<strlen(keystring);i++)
{
for(j=0;j<strlen(alph);j++)
{
if(keystring[i]==alph[j])
{
alphcheck=j;
for(k=alphcheck;k<(strlen(alph)-1);k++)
{
alph[k]=alph[k+1];
}
alph[strlen(alph)-1]='\0';
}
}
}
printf("alph:%s\n",alph);
keylen=strlen(keystring);
for(i=0;i<5;i++)
{
for(j=0;j<5;j++)
{
if(keylen>count)
{
table[i][j]=keystring[count];
}
else
{
table[i][j]=alph[alphnum];
alphnum++;
}
count++;
}
}
for(i=0;i<5;i++)
{
for(j=0;j<5;j++)
{
printf("%c ",table[i][j]);
}
printf("\n");
}
}
void Plain2Cypher(char table[][5])
{
char plain[30]="";
char encryption[30]="";
int i,j,k;
int check;
int plainlen=0;
int plainleft,plainright,plainreleft,plainreright;
printf("input plain string:");
gets(plain);
for(i=0;i<(strlen(plain)-1);i=i+2)
{
if(plain[i]==plain[i+1])
{
check=i+1;
for(j=(strlen(plain)-1);j>=check;j--)
{
plain[j+1]=plain[j];
}
plain[check]='X';
}
}
if(strlen(plain)%2==1)
{
plain[strlen(plain)]='X';
flag=1;
}
plain[strlen(plain)]='\0';
printf("plain:%s\n",plain);
for(i=0;i<strlen(plain);i++)
{
if(plain[i]=='Z')
{
plain[i]=='Q';
}
}
plainlen=strlen(plain);
for(k=0;k<plainlen;k=k+2)
{
for(i=0;i<5;i++)
{
for(j=0;j<5;j++)
{
if(table[i][j]==plain[k])
{
plainright=j;
plainreleft=i;
}
if(table[i][j]==plain[k+1])
{
plainleft=i;
plainreright=j;
}
}
}
if(plainreright==plainright)
{
encryption[k]=Encrypt_SameRow(table,plainreleft,plainright);
encryption[k+1]=Encrypt_SameRow(table,plainleft,plainreright);
}
else if(plainreleft==plainleft)
{
encryption[k]=Encrypt_SameColumn(table,plainreleft,plainright);
encryption[k+1]=Encrypt_SameColumn(table,plainleft,plainreright);
}
else
{
encryption[k]=Encrypt_DifferRowNColumn(table,plainleft,plainright);
encryption[k+1]=Encrypt_DifferRowNColumn(table,plainreleft,plainreright);
}
}
printf("encryption:%s\n",encryption);
}
char Encrypt_DifferRowNColumn(char table[][5],int i,int j)
{
return table[i][j];
}
char Encrypt_SameRow(char table[][5],int i,int j)
{
if(i==4)
{
return table[0][j];
}
else
{
return table[i+1][j];
}
}
char Encrypt_SameColumn(char table[][5], int i,int j)
{
if(j==4)
{
return table[i][0];
}
else
{
return table[i][j+1];
}
}
void Cypher2Plain(char table[][5])
{
char cypher[30]="";
char dencryption[30]="";
int i,j,k;
int check;
int cypherlen=0;
int cypherleft,cypherright,cypherreleft,cypherreright;
printf("input cypher string:");
gets(cypher);
cypherlen=strlen(cypher);
for(k=0;k<cypherlen;k=k+2)
{
for(i=0;i<5;i++)
{
for(j=0;j<5;j++)
{
if(table[i][j]==cypher[k])
{
cypherright=j;
cypherreleft=i;
}
if(table[i][j]==cypher[k+1])
{
cypherleft=i;
cypherreright=j;
}
}
}
if(cypherreright==cypherright)
{
dencryption[k]=Decrypt_SameRow(table,cypherreleft,cypherright);
dencryption[k+1]=Decrypt_SameRow(table,cypherleft,cypherreright);
}
else if(cypherreleft==cypherleft)
{
dencryption[k]=Decrypt_SameColumn(table,cypherreleft,cypherright);
dencryption[k+1]=Decrypt_SameColumn(table,cypherleft,cypherreright);
}
else
{
dencryption[k]=Decrypt_DifferRowNColumn(table,cypherleft,cypherright);
dencryption[k+1]=Decrypt_DifferRowNColumn(table,cypherreleft,cypherreright);
}
}
printf("dencryption:%s\n",dencryption);
if(flag==1)
{
dencryption[strlen(dencryption)-1]='\0';
}
for(i=1;i<strlen(dencryption);i=i+2)
{
if(dencryption[i]=='X')
{
if(dencryption[i-1]==dencryption[i+1])
{
for(j=i;j<(strlen(dencryption)-1);j++)
{
dencryption[j]=dencryption[j+1];
}
dencryption[strlen(dencryption)-1]='\0';
i=i-1;
}
}
}
printf("plain dencryption : %s\n",dencryption);
}
char Decrypt_DifferRowNColumn(char table[][5],int i,int j)
{
return table[i][j];
}
char Decrypt_SameRow(char table[][5],int i,int j)
{
if(i==0)
{
return table[4][j];
}
else
{
return table[i-1][j];
}
}
char Decrypt_SameColumn(char table[][5],int i,int j)
{
if(j==0)
{
return table[i][4];
}
else
{
return table[i][j-1];
}
}반응형
