bgneal@4: #ifndef CPP_ENIGMA_MACHINE_H
bgneal@4: #define CPP_ENIGMA_MACHINE_H
bgneal@4: // Copyright (C) 2012 by Brian Neal.
bgneal@4: // This file is part of Cpp-Enigma, the Enigma Machine simulation.
bgneal@4: // Cpp-Enigma is released under the MIT License (see License.txt).
bgneal@4: //
bgneal@4: // machine.h - This file contains the main Enigma machine class.
bgneal@4:
bgneal@4: #include <memory>
bgneal@4: #include <string>
bgneal@4: #include <vector>
bgneal@4: #include <cassert>
bgneal@4: #include "enigma_types.h"
bgneal@4: #include "rotor.h"
bgneal@4: #include "plugboard.h"
bgneal@4:
bgneal@4: namespace enigma
bgneal@4: {
bgneal@4: typedef std::vector<std::unique_ptr<rotor>> rotor_vector;
bgneal@4:
bgneal@4: class enigma_machine_error : public enigma_error
bgneal@4: {
bgneal@4: public:
bgneal@4: explicit enigma_machine_error(const std::string& what_arg)
bgneal@4: : enigma_error(what_arg)
bgneal@4: {}
bgneal@4: };
bgneal@4:
bgneal@4: class enigma_machine
bgneal@4: {
bgneal@4: public:
bgneal@4: // construct an Enigma machine from component parts:
bgneal@4: enigma_machine(rotor_vector rv,
bgneal@4: std::unique_ptr<rotor> reflector,
bgneal@4: const plugboard& pb);
bgneal@4:
bgneal@4: // construct an Enigma machine with a default plugboard (no cables connected):
bgneal@4: enigma_machine(rotor_vector rv,
bgneal@4: std::unique_ptr<rotor> reflector);
bgneal@4:
bgneal@4: // key-sheet style constructors:
bgneal@4: enigma_machine(const std::vector<std::string>& rotor_types,
bgneal@4: const std::vector<int>& ring_settings,
bgneal@4: const std::string& reflector_name = "B",
bgneal@4: const std::string& plugboard_settings = "");
bgneal@4:
bgneal@4: // set the rotor display (starting position) - 3 rotor version
bgneal@4: void set_display(char left, char mid, char right)
bgneal@4: {
bgneal@4: assert(rotors.size() == 3);
bgneal@4:
bgneal@4: rotors[0]->set_display(left);
bgneal@4: rotors[1]->set_display(mid);
bgneal@4: rotors[2]->set_display(right);
bgneal@4: }
bgneal@4:
bgneal@4: // set the rotor display (starting position) - 4 rotor version
bgneal@4: void set_display(char c0, char c1, char c2, char c3)
bgneal@4: {
bgneal@4: assert(rotors.size() == 4);
bgneal@4:
bgneal@4: rotors[0]->set_display(c0);
bgneal@4: rotors[1]->set_display(c1);
bgneal@4: rotors[2]->set_display(c2);
bgneal@4: rotors[3]->set_display(c3);
bgneal@4: }
bgneal@4:
bgneal@4: // return the rotor display (starting position) as a string
bgneal@4: std::string get_display() const
bgneal@4: {
bgneal@4: std::string result;
bgneal@4: for (const auto& r : rotors)
bgneal@4: {
bgneal@4: result += r->get_display();
bgneal@4: }
bgneal@4: return result;
bgneal@4: }
bgneal@4:
bgneal@4: // simulate front panel key press; returns the lamp character that is lit
bgneal@4: char key_press(char c)
bgneal@4: {
bgneal@4: step_rotors();
bgneal@4: return electric_signal(c - 'A') + 'A';
bgneal@4: }
bgneal@4:
bgneal@4: // Process a buffer of text of length n, placing the result in an output buffer.
bgneal@4: void process_text(const char* input, char* output, std::size_t n)
bgneal@4: {
bgneal@4: for (std::size_t i = 0; i < n; ++i)
bgneal@4: {
bgneal@4: *output++ = key_press(*input++);
bgneal@4: }
bgneal@4: }
bgneal@4:
bgneal@4: std::string process_text(const std::string& input)
bgneal@4: {
bgneal@4: std::string result;
bgneal@4: result.reserve(input.size());
bgneal@4:
bgneal@4: for (const auto& c : input)
bgneal@4: {
bgneal@4: result += key_press(c);
bgneal@4: }
bgneal@4: return result;
bgneal@4: }
bgneal@4:
bgneal@4: // for access to the plugboard for hill-climbing, etc
bgneal@4: plugboard& get_plugboard() { return pb; }
bgneal@4:
bgneal@4: private:
bgneal@4: rotor_vector rotors;
bgneal@4: std::unique_ptr<rotor> reflector;
bgneal@4: plugboard pb;
bgneal@4: rotor* r_rotor; // rightmost rotor
bgneal@4: rotor* m_rotor; // 2nd to right rotor
bgneal@4: rotor* l_rotor; // 3rd to right rotor
bgneal@4:
bgneal@4: void rotor_count_check();
bgneal@4:
bgneal@4: void step_rotors()
bgneal@4: {
bgneal@4: // The right-most rotor's right-side ratchet is always over a pawl, and
bgneal@4: // it has no neighbor to the right, so it always rotates.
bgneal@4: //
bgneal@4: // The middle rotor will rotate if either:
bgneal@4: // 1) The right-most rotor's left side notch is over the 2nd pawl
bgneal@4: // or
bgneal@4: // 2) It has a left-side notch over the 3rd pawl
bgneal@4: //
bgneal@4: // The third rotor (from the right) will rotate only if the middle rotor
bgneal@4: // has a left-side notch over the 3rd pawl.
bgneal@4: //
bgneal@4: // Kriegsmarine model M4 has 4 rotors, but the 4th rotor (the leftmost)
bgneal@4: // does not rotate (they did not add a 4th pawl to the mechanism).
bgneal@4:
bgneal@4: const bool l_rotate = m_rotor->notch_over_pawl();
bgneal@4: const bool m_rotate = l_rotate || r_rotor->notch_over_pawl();
bgneal@4:
bgneal@4: r_rotor->rotate();
bgneal@4: if (m_rotate)
bgneal@4: {
bgneal@4: m_rotor->rotate();
bgneal@4: }
bgneal@4: if (l_rotate)
bgneal@4: {
bgneal@4: l_rotor->rotate();
bgneal@4: }
bgneal@4: }
bgneal@4:
bgneal@4: // Simulate running an electric signal through the machine in order to
bgneal@4: // perform an encrypt or decrypt operation
bgneal@4: // signal_num - the wire (0-25) that the simulated current occurs on
bgneal@4: // Returns a lamp number to light (an integer 0-25).
bgneal@4: int electric_signal(int signal_num)
bgneal@4: {
bgneal@4: int pos = pb.signal(signal_num);
bgneal@4:
bgneal@4: for (auto r = rotors.rbegin(); r != rotors.rend(); ++r)
bgneal@4: {
bgneal@4: pos = (*r)->signal_in(pos);
bgneal@4: }
bgneal@4:
bgneal@4: pos = reflector->signal_in(pos);
bgneal@4:
bgneal@4: for (const auto& r : rotors)
bgneal@4: {
bgneal@4: pos = r->signal_out(pos);
bgneal@4: }
bgneal@4:
bgneal@4: return pb.signal(pos);
bgneal@4: }
bgneal@4: };
bgneal@4: }
bgneal@4:
bgneal@4: #endif