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71 lines
2.2 KiB
C++
71 lines
2.2 KiB
C++
/*This is a C++ Program to implement Vigenere cipher. The Vigenère cipher is a method of encrypting alphabetic text by using a series of different Caesar ciphers based on the letters of a keyword. It is a simple form of polyalphabetic substitution.*/
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#include <iostream>
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#include <string>
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using namespace std;
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class Vigenere
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{
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public:
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string key;
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Vigenere(string key)
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{
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for (int i = 0; i < key.size(); ++i)
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{
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if (key[i] >= 'A' && key[i] <= 'Z')
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this->key += key[i];
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else if (key[i] >= 'a' && key[i] <= 'z')
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this->key += key[i] + 'A' - 'a';
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}
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}
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string encrypt(string text)
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{
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string out;
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for (int i = 0, j = 0; i < text.length(); ++i)
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{
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char c = text[i];
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if (c >= 'a' && c <= 'z')
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c += 'A' - 'a';
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else if (c < 'A' || c > 'Z')
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continue;
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out += (c + key[j] - 2 * 'A') % 26 + 'A';
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j = (j + 1) % key.length();
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}
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return out;
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}
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string decrypt(string text)
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{
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string out;
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for (int i = 0, j = 0; i < text.length(); ++i)
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{
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char c = text[i];
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if (c >= 'a' && c <= 'z')
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c += 'A' - 'a';
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else if (c < 'A' || c > 'Z')
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continue;
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out += (c - key[j] + 26) % 26 + 'A';
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j = (j + 1) % key.length();
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}
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return out;
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}
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};
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int main()
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{
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Vigenere cipher("VIGENERECIPHER");
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string original =
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"Beware the Jabberwock, my son! The jaws that bite, the claws that catch!";
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string encrypted = cipher.encrypt(original);
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string decrypted = cipher.decrypt(encrypted);
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cout << original << endl;
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cout << "Encrypted: " << encrypted << endl;
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cout << "Decrypted: " << decrypted << endl;
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}
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/*
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Beware the Jabberwock, my son! The jaws that bite, the claws that catch!
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Encrypted: WMCEEIKLGRPIFVMEUGXQPWQVIOIAVEYXUEKFKBTALVXTGAFXYEVKPAGY
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Decrypted: BEWARETHEJABBERWOCKMYSONTHEJAWSTHATBITETHECLAWSTHATCATCH
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