ADFGVX cipher: Difference between revisions
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ATTACKAT1200AM
</pre>
=={{header|C++}}==
<syntaxhighlight lang="c++">
#include <algorithm>
#include <cstdint>
#include <fstream>
#include <iostream>
#include <random>
#include <sstream>
#include <stdexcept>
#include <string>
#include <unordered_set>
#include <vector>
const std::string ADFGVX = "ADFGVX";
const std::string ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
std::random_device random;
std::mt19937 mersenne_twister(random());
std::vector<std::vector<char>> initialise_polybius_square() {
std::vector<char> letters(ALPHABET.begin(), ALPHABET.end());
std::shuffle(letters.begin(), letters.end(), mersenne_twister);
std::vector<std::vector<char>> result = { 6, std::vector<char>(6, 0) };
for ( int32_t row = 0; row < 6; ++row ) {
for ( int32_t column = 0; column < 6; ++column ) {
result[row][column] = letters[6 * row + column];
}
}
return result;
}
// Create a key using a word from the dictionary 'unixdict.txt'
std::string create_key(const uint64_t& size) {
if ( size < 7 || size > 12 ) {
throw std::invalid_argument("Key should contain between 7 and 12 letters, both inclusive.");
}
std::vector<std::string> candidates;
std::fstream file_stream;
file_stream.open("../unixdict.txt");
std::string word;
while ( file_stream >> word ) {
std::transform(word.begin(), word.end(), word.begin(), [](const char& ch){ return std::toupper(ch); });
if ( word.length() == size
&& word.length() == std::unordered_set<char>{ word.begin(), word.end() }.size()
&& word.find_first_not_of(ALPHABET) == std::string::npos ) {
candidates.emplace_back(word);
}
}
std::shuffle(candidates.begin(), candidates.end(), mersenne_twister);
std::string key = candidates[0];
return key;
}
std::string encrypt(const std::string& plain_text,
const std::vector<std::vector<char>>& polybius,
const std::string& key) {
std::string code = "";
for ( const char& ch : plain_text ) {
for ( int32_t row = 0; row < 6; ++row ) {
for ( int32_t column = 0; column < 6; ++column ) {
if ( polybius[row][column] == ch ) {
code += ADFGVX[row];
code += ADFGVX[column];
}
}
}
}
std::string encrypted = "";
for ( const char& ch : key ) {
for ( uint64_t i = key.find(ch); i < code.length(); i += key.length() ) {
encrypted += code[i];
}
encrypted += " ";
}
return encrypted;
}
std::string decrypt(const std::string& encrypted_text,
const std::vector<std::vector<char>>& polybius,
const std::string& key) {
const uint64_t space_count = std::count(encrypted_text.begin(), encrypted_text.end(), ' ');
const uint64_t code_size = encrypted_text.length() - space_count;
std::vector<std::string> blocks;
std::stringstream stream(encrypted_text);
std:: string word;
while ( stream >> word ) {
blocks.emplace_back(word);
}
std::string code = "";
for ( int32_t i = 0; code.length() < code_size; ++i ) {
for ( const std::string& block : blocks ) {
if ( code.length() < code_size ) {
code += block[i];
}
}
}
std::string plain_text = "";
for ( uint64_t i = 0; i < code_size - 1; i += 2 ) {
int32_t row = ADFGVX.find(code[i]);
int32_t column = ADFGVX.find(code[i + 1]);
plain_text += polybius[row][column];
}
return plain_text;
}
int main() {
const std::vector<std::vector<char>> polybius = initialise_polybius_square();
std::cout << "The 6 x 6 Polybius square:" << std::endl;
std::cout << " | A D F G V X" << std::endl;
std::cout << "--------------" << std::endl;
for ( int32_t row = 0; row < 6; ++row ) {
std::cout << ADFGVX[row] << "|";
for ( int32_t column = 0; column < 6; ++column ) {
std::cout << " " << polybius[row][column];
}
std::cout << std::endl;
}
std::cout << std::endl;
const std::string key = create_key(9);
std::cout << "The key is " << key << std::endl << std::endl;
const std::string plain_text = "ATTACKAT1200AM";
std::cout << "Plain text: " << plain_text <<std::endl << std::endl;
const std::string encrypted_text = encrypt(plain_text, polybius, key);
std::cout << "Encrypted: " << encrypted_text << std::endl << std::endl;
const std::string decrypted_text = decrypt(encrypted_text, polybius, key);
std::cout << "Decrypted: " << decrypted_text << std::endl;
}
</syntaxhighlight>
{{ out }}
<pre>
The 6 x 6 Polybius square:
| A D F G V X
--------------
A| X Q I Z 1 K
D| A O Y 2 S 5
F| G 7 J R 9 T
G| 0 3 E P C V
V| N 6 D L H B
X| U 4 F W M 8
The key is HORSETAIL
Plain text: ATTACKAT1200AM
Encrypted: DVDV AAG FXG XDA FAG XFA DXD AAA GVX
Decrypted: ATTACKAT1200AM
</pre>
=={{header|F_Sharp|F#}}==
<syntaxhighlight lang="fsharp">
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