Crypto

Hill Chrome:

#include <iostream>
#include <string>
#include <math.h>
using namespace std;
int main()
{
    char plaintext[3];
    int key[3][3];
    cout<<"Enter the elements for the key(integers only):"<<endl;
    for(int i=0;i<3;i++)
        for(int j=0;j<3;j++)
            cin>>key[i][j];
    cout<<"The entered key is :"<<endl;
    for(int i=0;i<3;i++)
    {
        cout<<"\n";
        for(int j=0;j<3;j++)
            cout<<key[i][j]<<" ";
    }
    cout<<"\n";
    cout<<"Enter a three letter word:"<<endl;
    cin>>plaintext;
    int message[3][1];
    for(int k=0;k<3;k++)
        for(int j=0;j<1;j++)
            message[k][j]=((int)plaintext[k]-97);
    cout<<"The message matrix is:"<<endl;
    for(int i=0;i<3;i++)
    {
        cout<<"\n";
        for(int j=0;j<1;j++)
            cout<<message[i][j];
    }
    cout<<"\n";
    cout<<"The multiplied matrix is:"<<endl;
    int k,i,j;
    int c[3][1];
    for(i=0;i<3;++i)
    {
        for(j=0;j<1;++j)
        {
            c[i][j]=0;
            for(k=0;k<3;++k)
                c[i][j]=c[i][j]+(key[i][k]*message[k][j]);
            cout<<c[i][j]<<" ";
        }
        cout<<"\n";
    }
    cout<<"The encrypted data is:"<<endl;
    for(int i=0;i<1;i++)
    {
        cout<<"\n";
        for(int j=0;j<3;j++)
            cout<<(char)((fmod(c[i][j],26)+97));
    }
    cout<<"\n";
    float det=0;
    float ikey[3][3];
    for(i = 0; i < 3; i++)
        det=det + (key[0][i] * (key[1][(i+1)%3] * key[2][(i+2)%3] - key[1][(i+2)%3] * key[2][(i+1)%3]));
    cout<<"Inverse of matrix is:"<<endl;
    for(i = 0; i < 3; i++){
        for(j = 0; j < 3; j++)
        {
            cout<<((key[(j+1)%3][(i+1)%3] * key[(j+2)%3][(i+2)%3]) - (key[(j+1)%3][(i+2)%3] * key[(j+2)%3][(i+1)%3]))/det<<"\t";
            ikey[i][j]=((key[(j+1)%3][(i+1)%3] * key[(j+2)%3][(i+2)%3]) - (key[(j+1)%3][(i+2)%3] * key[(j+2)%3][(i+1)%3]))/det;
        }
        cout<<"\n";
    }
    float decrypt[3][1];
    for(i=0;i<3;i++)
    {
        for(j=0;j<1;j++)
        {
            decrypt[i][j]=0;
            for(k=0;k<3;k++)
                decrypt[i][j]=decrypt[i][j]+(ikey[i][k]*c[k][j]);
            cout<<decrypt[i][j]<<" ";
        }
        cout<<"\n";
    }
    cout<<"The decrypted data is:"<<endl;
    for(i=0;i<3;i++)
        cout<<(char)(fmod(decrypt[i][0],26)+97);
}
-----------------------------------------------------------------------------------
Affine:
#include <iostream>
#include <string>
#include <math.h>
using namespace std;
int main()
{
    string plaintext,encrypt,decrypt;
    int inv;
    cout<<"Enter the message to be encrypted:"<<endl;
    getline(cin,plaintext);
    float a,b;
    cout<<"Enter the values for a and b:"<<endl;
    cin>>a>>b;
    int length=(int)plaintext.length();
    for(int i=0;i<length;i++)
    {
        encrypt[i]=(char)(fmod((a*(plaintext[i]-97)+b),26)+97);
    }
    for(int i=0;i<length;i++)
    {
        if(encrypt[i]=='V')
        {
            cout<<" ";
        }
        else
        {
            cout<<encrypt[i];
        }
    }
    cout<<"\n";
    cout<<"The deciphered text is:"<<endl;
    int f=0;
    inv=0;
    for(int i=0;i<26;i++)
    {
        f=fmod((a*i),26);
        if(f==1)
        {
            inv=i;
        }
    }
    for(int i=0;i<length;i++)
    {
        decrypt[i]=(char)(fmod(inv*((encrypt[i]-97)-b),26)+97);
    }
    for(int i=0;i<length;i++)
    {
        if(decrypt[i]=='T')
        {
            cout<<" ";
        }
        else
        {
            cout<<decrypt[i];
        }
    }
}
---------------------------------------------------------------------------------------------------------

Play Fair Cipher:

#include <stdio.h>
#define siz 5
void encrypt(int *i, int *j)
{
(*i)++,(*j)++;
if((*i)==siz) *i=0;
else if((*j)==siz) *j=0;
}
void playfair(char ch1,char ch2, char mat[siz][siz])
{
int j,m,n,p,q,c,k;
for(j=0,c=0;(c<2)||(j<siz);j++)
for(k=0;k<siz;k++)
if(mat[j][k] == ch1)
m=j,n=k,c++;
else if(mat[j][k] == ch2)
p=j,q=k,c++;
if(m==p)
encrypt(&n,&q);
else if(n==q)
encrypt(&m,&p);
else
n+=q,q=n-q,n-=q;
printf("%c%c",mat[m][n],mat[p][q]);
}
void main()
{
char mat[siz][siz],key[10],str[25]={0};
int m,n,i,j;
char temp;

printf("Enter Key:");
gets(key);
m=n=0;
for(i=0;key[i]!='\0';i++)
{
for(j=0;j<i;j++)
if(key[j] == key[i]) break;
if(key[i]=='j') key[i]='i';
if(j>=i)
{
mat[m][n++] = key[i];
if(n==siz)
n=0,m++;
}
}
for(i=97;i<=122;i++)
{
for(j=0;key[j]!='\0';j++)
if(key[j] == i)
break;
else if(i=='j')
break;

if(key[j]=='\0')
{
mat[m][n++] = i;
if(n==siz) n=0,m++;
}
}
printf("Enter input String:");
gets(str);
printf("\n\nMatrix :\n");
for(i=0;i<siz;i++)
{
for(j=0;j<siz;j++)
printf("%c\t",mat[i][j]);
printf("\n");
}
printf("\n\nEntered text :%s\nCipher Text :",str);

for(i=0;str[i]!='\0';i++)
{
temp = str[i++];
if(temp == 'j') temp='i';
if(str[i]=='\0')
playfair(temp,'x',mat);
else
{
if(str[i]=='j') str[i]='i';
if(temp == str[i])
{
playfair(temp,'x',mat);
playfair('x',str[i],mat);
}
else
playfair(temp,str[i],mat);
}
}
}

---------------------------------------------------------------------------
Ceaser Cipher:

#include <iostream>
#include <string>
using namespace std;
int key;
char caesar(char);
int main()
{
    	string input;
    	cout<<"Enter the key:";
    	cin>>key;
        cout << "Enter the text: " << endl;
        cin>>input;
        string output = "";
        for (int x = 0; x < input.length(); x++)
        {
            output += caesar(input[x]);
        }
        cout << output << endl;
}

char caesar(char c)
{
    if (isalpha(c))
    {
        c = toupper(c);
        c = (((c - 65) + key) % 26) + 65;
    }
    return c;
}
------------------------------------------------------------------------------
RSA:

#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#include<math.h>
#include<string.h>

long int p,q,n,t,flag,e[100],d[100],temp[100],j,m[100],en[100],i;
char msg[100];
int prime(long int);
void ce();
long int cd(long int);
void encrypt();
void decrypt();
void main()
{
clrscr();
printf("\nENTER FIRST PRIME NUMBER\n");
scanf("%d",&p);
flag=prime(p);
if(flag==0)
{
    printf("\nWRONG INPUT\n");
    getch();
    exit(1);
}
printf("\nENTER ANOTHER PRIME NUMBER\n");
scanf("%d",&q);
flag=prime(q);
if(flag==0||p==q)
{
    printf("\nWRONG INPUT\n");
    getch();
    exit(1);
}
printf("\nENTER MESSAGE\n");
fflush(stdin);
scanf("%s",msg);
for(i=0;msg[i]!=NULL;i++)
m[i]=msg[i];
n=p*q;
t=(p-1)*(q-1);
ce();
printf("\nPOSSIBLE VALUES OF e AND d ARE\n");
for(i=0;i<j-1;i++)
printf("\n%ld\t%ld",e[i],d[i]);
encrypt();
decrypt();
getch();
}
int prime(long int pr)
{
int i;
j=sqrt(pr);
for(i=2;i<=j;i++)
{
    if(pr%i==0)
    return 0;
}
return 1;
}
void ce()
{
int k;
k=0;
for(i=2;i<t;i++)
{
    if(t%i==0)
    continue;
    flag=prime(i);
    if(flag==1&&i!=p&&i!=q)
    {
        e[k]=i;
        flag=cd(e[k]);
        if(flag>0)
        {
            d[k]=flag;
            k++;
        }
        if(k==99)
        break;
    }
}
}
long int cd(long int x)
{
long int k=1;
while(1)
{
    k=k+t;
    if(k%x==0)
    return(k/x);
}
}
void encrypt()
{
long int pt,ct,key=e[0],k,len;
i=0;
len=strlen(msg);
while(i!=len)
{
    pt=m[i];
    pt=pt-96;
    k=1;
    for(j=0;j<key;j++)
    {
        k=k*pt;
        k=k%n;
    }
    temp[i]=k;
    ct=k+96;
    en[i]=ct;
    i++;
}
en[i]=-1;
printf("\nTHE ENCRYPTED MESSAGE IS\n");
for(i=0;en[i]!=-1;i++)
printf("%c",en[i]);
}
void decrypt()
{
long int pt,ct,key=d[0],k;
i=0;
while(en[i]!=-1)
{
    ct=temp[i];
    k=1;
    for(j=0;j<key;j++)
    {
        k=k*ct;
        k=k%n;
    }
    pt=k+96;
    m[i]=pt;
    i++;
}
m[i]=-1;
printf("\nTHE DECRYPTED MESSAGE IS\n");
for(i=0;m[i]!=-1;i++)
printf("%c",m[i]);
}
----------------------------------------------------------------------
Vigenere

#include <iostream>
#include <string>
#include <math.h>
using namespace std;
int main()
{
    char plaintext[3];
    int key[3][3];
    cout<<"Enter the elements for the key(integers only):"<<endl;
    for(int i=0;i<3;i++)
        for(int j=0;j<3;j++)
            cin>>key[i][j];
    cout<<"The entered key is :"<<endl;
    for(int i=0;i<3;i++)
    {
        cout<<"\n";
        for(int j=0;j<3;j++)
            cout<<key[i][j]<<" ";
    }
    cout<<"\n";
    cout<<"Enter a three letter word:"<<endl;
    cin>>plaintext;
    int message[3][1];
    for(int k=0;k<3;k++)
        for(int j=0;j<1;j++)
            message[k][j]=((int)plaintext[k]-97);
    cout<<"The message matrix is:"<<endl;
    for(int i=0;i<3;i++)
    {
        cout<<"\n";
        for(int j=0;j<1;j++)
            cout<<message[i][j];
    }
    cout<<"\n";
    cout<<"The multiplied matrix is:"<<endl;
    int k,i,j;
    int c[3][1];
    for(i=0;i<3;++i)
    {
        for(j=0;j<1;++j)
        {
            c[i][j]=0;
            for(k=0;k<3;++k)
                c[i][j]=c[i][j]+(key[i][k]*message[k][j]);
            cout<<c[i][j]<<" ";
        }
        cout<<"\n";
	}
    cout<<"The encrypted data is:"<<endl;
    for(int i=0;i<1;i++)
    {
    	cout<<"\n";
        for(int j=0;j<3;j++)
            cout<<(char)((fmod(c[i][j],26)+97));
    }
    cout<<"\n";
    float det=0;
    float ikey[3][3];
    for(i = 0; i < 3; i++)
        det=det + (key[0][i] * (key[1][(i+1)%3] * key[2][(i+2)%3] - key[1][(i+2)%3] * key[2][(i+1)%3]));
    cout<<"Inverse of matrix is:"<<endl;
    for(i = 0; i < 3; i++){
        for(j = 0; j < 3; j++)
        {
            cout<<((key[(j+1)%3][(i+1)%3] * key[(j+2)%3][(i+2)%3]) - (key[(j+1)%3][(i+2)%3] * key[(j+2)%3][(i+1)%3]))/det<<"\t";
            ikey[i][j]=((key[(j+1)%3][(i+1)%3] * key[(j+2)%3][(i+2)%3]) - (key[(j+1)%3][(i+2)%3] * key[(j+2)%3][(i+1)%3]))/det;
        }
        cout<<"\n";
    }
    float decrypt[3][1];
    for(i=0;i<3;i++)
    {
        for(j=0;j<1;j++)
        {
            decrypt[i][j]=0;
            for(k=0;k<3;k++)
                decrypt[i][j]=decrypt[i][j]+(ikey[i][k]*c[k][j]);
            cout<<decrypt[i][j]<<" ";
        }
        cout<<"\n";
    }
    cout<<"The decrypted data is:"<<endl;
    for(i=0;i<3;i++)
        cout<<(char)(fmod(decrypt[i][0],26)+97);
}
---------------------------------------------------------------------------------

Vignere Cipher:

#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <process.h>
void vigenereCipher(char *,char *);
void encipher();
void decipher();
int main()
{
     int choice;
     while(1)
     {
          printf("1. Encrypt Text \n");
          printf("2. Decrypt Text \n");
          printf("3. Exit \n");
          printf("Enter Your Choice : ");
          scanf("%d",&choice);
          fflush(stdin);
          if(choice == 3)
               exit(0);
          else if(choice == 1)
               encipher();
          else if(choice == 2)
               decipher();
          else
               printf("Please Enter Valid Option.");
     }
     return 0;
}
void encipher()
{
     unsigned int i,j;
     char input[257],key[33];
     printf("Enter Text to be Encrypted [Max. 256 characters/ only alphabets]:n ");
     gets(input);
     printf("Enter Encryption Key [Max. 32 Characters/ only alphabets]: ");
     gets(key);
     for(i=0,j=0;i<strlen(input);i++,j++)
     {
          if(j>=strlen(key))
          {
               j=0;
          }
          printf("%c",65+(((toupper(input[i])-65)+(toupper(key[j])-65))%26));
     }
}
void decipher()
{
     unsigned int i,j;
     char input[257],key[33];
     int value;
     printf("Enter Text to be Decrypted [Max. 256 characters/ only alphabets]:n ");
     gets(input);
     printf("Enter Decryption Key [Max. 32 Characters/ only aphabets]: ");
     gets(key);
     for(i=0,j=0;i<strlen(input);i++,j++)
     {
          if(j>=strlen(key))
          {
               j=0;
          }
          value = (toupper(input[i])-64)-(toupper(key[j])-64);
          if( value < 0)
          {
               value = value * -1;
          }
          printf("%c",65 + (value % 26));
     }
}