Create Vigenere Cipher

Vigenere Cipher

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+// C++ code to implement Vigenere Cipher
+#include<bits/stdc++.h>
+using namespace std;
+string generateKey(string str, string key)
+{
+	int x = str.size();
+
+	for (int i = 0; ; i++)
+	{
+		if (x == i)
+			i = 0;
+		if (key.size() == str.size())
+			break;
+		key.push_back(key[i]);
+	}
+	return key;
+}
+string cipherText(string str, string key)
+{
+	string cipher_text;
+
+	for (int i = 0; i < str.size(); i++)
+	{
+		// converting in range 0-25
+		char x = (str[i] + key[i]) %26;
+
+		// convert into alphabets(ASCII)
+		x += 'A';
+
+		cipher_text.push_back(x);
+	}
+	return cipher_text;
+}
+
+string originalText(string cipher_text, string key)
+{
+	string orig_text;
+
+	for (int i = 0 ; i < cipher_text.size(); i++)
+	{
+		// converting in range 0-25
+		char x = (cipher_text[i] - key[i] + 26) %26;
+
+		// convert into alphabets(ASCII)
+		x += 'A';
+		orig_text.push_back(x);
+	}
+	return orig_text;
+}
+
+// Driver program to test the above function
+int main()
+{
+	string str = "GEEKSFORGEEKS";
+	string keyword = "AYUSH";
+
+	string key = generateKey(str, keyword);
+	string cipher_text = cipherText(str, key);
+
+	cout << "Ciphertext : "
+		<< cipher_text << "\n";
+
+	cout << "Original/Decrypted Text : "
+		<< originalText(cipher_text, key);
+	return 0;
+}