PHP-Fusion Powered Website - Articles: C++ Program to Decrypt Message using Playfair Cipher

Users Online

· Guests Online: 44

· Members Online: 0

· Total Members: 188
· Newest Member: meenachowdary055

Forum Threads

Newest Threads

No Threads created

Hottest Threads

No Threads created

Latest Articles

· Do while loop
· The for loop in C
· C while loop
· Pointers in C
· Functions in C

Oh no! Where's the JavaScript?
Your Web browser does not have JavaScript enabled or does not support JavaScript. Please enable JavaScript on your Web browser to properly view this Web site,
or upgrade to a Web browser that does support JavaScript; Firefox, Safari, Opera, Chrome or a version of Internet Explorer newer then version 6.

Articles Hierarchy

Articles Home » C++ » C++ Program to Decrypt Message using Playfair Cipher

C++ Program to Decrypt Message using Playfair Cipher

This C++ program decodes any message encoded using the technique of traditional playfair cipher. The Playfair cipher or Playfair square is a manual symmetric encryption technique and was the first literal digraph substitution cipher. Input is not case sensitive and works only for characters from ‘a’ to ‘z’ and ‘A’ to ‘Z’.

This C++ program is successfully compiled and tested on our system. The program output is given below.

```
/*
```

 * C++ Program to Decode a Message Encoded Using Playfair Cipher

```
 */
```
```
#include<iostream>
```
```
#include<vector>
```
```
using namespace std;
```
```
 
```

const char encoder[5][5] = {{'A','B','C','D','E'},

                      {'F','G','H','I','K'},

                      {'L','M','N','O','P'},

                      {'Q','R','S','T','U'},

                      {'V','W','X','Y','Z'}};

```
 
```
```
void input_string(vector<char>& a)
```
```
{
```
```
    char c;
```
```
    while (1)
```
```
    {
```
```
        c=getchar();
```
```
        if (c >= 97 && c <= 122)
```
```
        c -= 32;
```
```
        if (c == '\n')
```
```
            break;
```
```
        else if (c==' ')
```
```
            continue;
```
```
        else if (c == 'J')
```
```
        a.push_back('I');
```
```
        a.push_back(c);
```
```
    }
```
```
    return;
```
```
}
```
```
 
```
```
 
```
```
 
```
```
void get_pos(char p, int& r, int& c)
```
```
{
```
```
    if (p < 'J')
```
```
    {
```
```
        r = (p - 65) / 5;
```
```
        c = (p - 65) % 5;
```
```
    }
```
```
    else if (p > 'J')
```
```
    {
```
```
        r = (p - 66) / 5;
```
```
        c = (p - 66) % 5;
```
```
    }
```
```
    return;
```
```
}
```
```
 
```

void same_row(int r, vector<char>& code, int c1, int c2)

```
{
```

    code.push_back(encoder[r][(c1 + 4) % 5]);

    code.push_back(encoder[r][(c2 + 4) % 5]);

```
    return;
```
```
}
```
```
 
```

void same_column(int c, vector<char>& code, int r1, int r2)

```
{
```

    code.push_back(encoder[(r1 + 4) % 5][c]);

    code.push_back(encoder[(r2 + 4) % 5][c]);

```
    return;
```
```
}
```
```
 
```

void diff_col_row(int r1, int c1, vector<char>& code, int r2, int c2)

```
{
```
```
    code.push_back(encoder[r1][c2]);
```
```
    code.push_back(encoder[r2][c1]);
```
```
    return;
```
```
}
```
```
 
```
```
 
```
```
void encode(vector<char> msgx, int len)
```
```
{
```
```
    vector<char> code;
```
```
    int i = 0, j = 0;
```
```
    int r1, c1, r2, c2;
```
```
    while (i < len)
```
```
    {
```
```
        get_pos(msgx[i], r1, c1);
```
```
        i++;
```
```
        get_pos(msgx[i], r2, c2);
```
```
        if (r1 == r2)
```
```
        {
```
```
            same_row(r1, code, c1, c2);
```
```
        }
```
```
        else if (c1 == c2)
```
```
        {
```

            same_column(c1, code, r1, r2);

```
        }
```
```
        else
```
```
        {
```

            diff_col_row(r1, c1, code, r2, c2);

```
        }
```
```
        i++;
```
```
    }
```
```
    cout<<"\nCODE: ";
```
```
    for (j = 0;j < code.size();j++)
```
```
    {
```
```
        if (code[j] == 'X')
```
```
        continue;
```
```
        cout<<code[j];
```
```
    }
```
```
    return;
```
```
}
```
```
 
```
```
 
```
```
int main()
```
```
{
```
```
    vector<char> msg;
```

    std::cout<<"Enter the Encrypted Message:";

```
    input_string(msg);
```
```
    int len=msg.size();
```
```
    encode(msg,len);
```
```
    return 0;
```
```
}
```

Output:
 
Enter the Encrypted Message:CBNVMPPO
CODE: BALLOON

Users Online

Forum Threads

Latest Articles

Articles Hierarchy

C++ Program to Decrypt Message using Playfair Cipher

C++ Program to Decrypt Message using Playfair Cipher

Comments

Post Comment

Ratings