railcipher.cpp

#include<iostream>
#include<string.h>

using namespace std;

void encryptMsg(char msg[], int key){
int msgLen = strlen(msg), i, j, k = -1, row = 0, col = 0;
char railMatrix[key][msgLen];

for(i = 0; i < key; ++i)
for(j = 0; j < msgLen; ++j)
railMatrix[i][j] = '\n';

for(i = 0; i < msgLen; ++i){
	railMatrix[row][col++] = msg[i];
	if(row == 0 || row == key-1)
		k= k * (-1);
	row = row + k;
}

cout<<"\nEncrypted Message: ";

for(i = 0; i < key; ++i)
for(j = 0; j < msgLen; ++j)
if(railMatrix[i][j] != '\n')
	cout<<railMatrix[i][j];
}

void decryptMsg(char enMsg[], int key){
int msgLen = strlen(enMsg), i, j, k = -1, row = 0, col = 0, m = 0;
char railMatrix[key][msgLen];

for(i = 0; i < key; ++i)
for(j = 0; j < msgLen; ++j)
railMatrix[i][j] = '\n';

for(i = 0; i < msgLen; ++i){
	railMatrix[row][col++] = '*';
	if(row == 0 || row == key-1)
		k= k * (-1);
	row = row + k;
}

for(i = 0; i < key; ++i) 
for(j = 0; j < msgLen; ++j)
if(railMatrix[i][j] == '*')
railMatrix[i][j] = enMsg[m++];
row = col = 0;
k = -1;
cout<<"\nDecrypted Message: ";

for(i = 0; i < msgLen; ++i){
	cout<<railMatrix[row][col++];

	if(row == 0 || row == key-1)
		k= k * (-1);
	row = row + k;
}
}

int main(){
char msg[] = "Hello World"; char enMsg[] = "Horel ollWd"; int key = 3;

cout<<"Original Message: "<<msg;

encryptMsg(msg, key);
decryptMsg(enMsg, key);

return 0;
}