Substitution cipher:Which one? - c++

Question

I'm a beginner and I have a question(somehow silly and stupid :) )...Today I decided to challenge myself and I came around the challenge that wanted me to create a program that ciphers (or encrypts) the message using the substitution cipher method...I solved the challenge by myself but mine is way different than the solution itself...I just want to know which one is better and why? and also is there anything I missed in my own code?
So here is the code I've written:
#include <iostream>
#include <string>
using namespace std;
int main()
{
string secretMessage {};
string alphabet {"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"};
string key {"XZNLWEBGJHQDYVTKFUOMPCIASRxznlwebgjhqdyvtkfuompciasr"};
cout << "Enter your secret message: ";
getline(cin, secretMessage);
//Encryption
for(size_t i{0}; i<secretMessage.length(); ++i){
for(size_t j{0}; j<alphabet.length(); ++j){
if (secretMessage.at(i) == alphabet.at(j)){
secretMessage.at(i) = key.at(j);
break;
}
}
}
cout << "Encrypting The Message..." << endl;
cout << "Encrypted Message: " << secretMessage << endl;
//Decryption
for(size_t i{0}; i<secretMessage.length(); ++i){
for(size_t j{0}; j<key.length(); ++j){
if (secretMessage.at(i) == key.at(j)){
secretMessage.at(i) = alphabet.at(j);
break;
}
}
}
cout << "\nDecrypting The Encryption..." << endl;
cout << "Decrypted: " << secretMessage << endl;
return 0;
}
And here is the solution:
#include <iostream>
#include <string>
using namespace std;
int main()
{
string secretMessage {};
string alphabet {"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"};
string key {"XZNLWEBGJHQDYVTKFUOMPCIASRxznlwebgjhqdyvtkfuompciasr"};
string encryptedMessage {};
string decryptedMessage {};
cout << "Enter your secret message: ";
getline(cin, secretMessage);
cout << "\nEncrypting Message..." << endl;
//Encryption
for(char c:secretMessage){
size_t position = alphabet.find(c);
if (position != string::npos){
char newChar {key.at(position)};
encryptedMessage += newChar;
} else{
encryptedMessage += c;
}
}
cout << "Encrypted Message: " << encryptedMessage << endl;
//Decryption
cout << "\nDecrypting Message..." << endl;
for(char c:encryptedMessage){
size_t position = key.find(c);
if (position != string::npos){
char newChar {alphabet.at(position)};
decryptedMessage += newChar;
} else{
decryptedMessage += c;
}
}
cout << "Decrypted Message: " << decryptedMessage << endl;
return 0;
}
Note:I have also included the decryption part too

Answer 1

I find both code snipets rather complex.
Please have a look at this more easy solution
#include <iostream>
#include <string>
#include <algorithm>
int main()
{
// The encoding alphabet and key
constexpr std::string_view alphabet{ "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ _" };
constexpr std::string_view key{ "ZYXWVUTSRQPONMLKJIHGFEDCBAzyxwvutsrqponmlkjihgfedcba_ " };
// String to encrypt
std::string message{"Hello world"};
// Here we will store the result
std::string result;
std::transform(message.begin(), message.end(), std::back_inserter(result), [&key, &alphabet](const char c)
{ size_t pos{ alphabet.find(c) }; return (pos != std::string::npos) ? key[pos] : '_'; });
// Show result
std::cout << "\nEncrypted: " << result << "\n";
message = result;
result.clear();
std::transform(message.begin(), message.end(), std::back_inserter(result), [&key, &alphabet](const char c)
{ size_t pos{ alphabet.find(c) }; return (pos != std::string::npos) ? key[pos] : '_'; });
// Show result
std::cout << "\nDecrypted: " << result << "\n";
return 0;
}
This is using more modern C++ language elements. Encrypting and decrypting is implemented via one std::transform statement each.
Of course you should never use such encoding in real live, because the key is visible in the exe file.
Anyway, maybe it helps you to have some more ideas . . .