Add subdirectory for cryptography examples

+ Add example using columnar transposition for encrypting / decrypting messages
+ Fix cmake build error from duplicate lib-bst when building from project root

cpp/CMakeLists.txt

@@ -19,6 +19,7 @@ project(
 
 add_subdirectory(algorithms)
 add_subdirectory(cmake)
+add_subdirectory(cryptography)
 add_subdirectory(datastructs)
 add_subdirectory(graphics)
 add_subdirectory(patterns)

cpp/algorithms/trees/binary/CMakeLists.txt

@@ -15,7 +15,7 @@ project (
     LANGUAGES   CXX
 )
 
-add_library(lib-bst "bst.cpp")
+add_library(lib-bst-algo "bst.cpp")
 
-add_executable(test-bst "driver.cpp")
-target_link_libraries(test-bst lib-bst)
+add_executable(test-bst-algo "driver.cpp")
+target_link_libraries(test-bst-algo lib-bst)

cpp/cryptography/CMakeLists.txt

@@ -0,0 +1,18 @@
+###############################################################################
+## Author: Shaun Reed                                                        ##
+## Legal: All Content (c) 2021 Shaun Reed, all rights reserved               ##
+## About: A root project for practicing cryptography in C++                  ##
+##                                                                           ##
+## Contact: shaunrd0@gmail.com  | URL: www.shaunreed.com | GitHub: shaunrd0  ##
+##############################################################################
+#
+cmake_minimum_required(VERSION 3.15)
+
+project (
+    #[[NAME]]   Cryptography
+    VERSION     1.0
+    DESCRIPTION "A project for practicing cryptography in C++"
+    LANGUAGES   CXX
+)
+
+add_subdirectory(columnar-transposition)

cpp/cryptography/columnar-transposition/CMakeLists.txt

@@ -0,0 +1,22 @@
+################################################################################
+## Author: Shaun Reed                                                         ##
+## Legal: All Content (c) 2021 Shaun Reed, all rights reserved                ##
+## About: A root project for practicing columnar transposition cipher in C++  ##
+##                                                                            ##
+## Contact: shaunrd0@gmail.com  | URL: www.shaunreed.com | GitHub: shaunrd0   ##
+################################################################################
+#
+
+cmake_minimum_required(VERSION 3.15)
+
+project(
+    #[[NAME]]   ColumnarTransposition
+    VERSION     1.0
+    DESCRIPTION "Practice implementing columnar transposition in C++"
+    LANGUAGES CXX
+)
+
+add_library(lib-cipher "lib-cipher.cpp")
+
+add_executable(columnar-transposition-test "driver.cpp")
+target_link_libraries(columnar-transposition-test lib-cipher)

cpp/cryptography/columnar-transposition/driver.cpp

@@ -0,0 +1,85 @@
+/*##############################################################################
+## Author: Shaun Reed                                                         ##
+## Legal: All Content (c) 2021 Shaun Reed, all rights reserved                ##
+## About: An example of using columnar transposition cipher                   ##
+## + Using concept at www.braingle.com/brainteasers/codes/columnartrans.php   ##
+##                                                                            ##
+## Contact: shaunrd0@gmail.com  | URL: www.shaunreed.com | GitHub: shaunrd0   ##
+################################################################################
+*/
+
+#include "lib-cipher.hpp"
+
+#include<iostream>
+
+// Columnar transposition cipher
+// https://www.braingle.com/brainteasers/codes/columnartrans.php#form
+// NOTE: Must check the 'irregular case' box to produce same results
+// + I only used the irregular case to encrypt and decrypt
+// + I did not write any code for testing with the regular case
+
+
+/******************************************************************************/
+// Main program loop
+int main (const int argc, const char * argv[]) {
+  // Left some test cases I used commented out :)
+
+  // Using example keyword from www.braingle.com
+  // + The embedded example there doesn't seem to support numbers in keywords :(
+  CipherData cData("ZEBRAS");
+
+  // Taking user input for keyword using CipherData ctor
+//  CipherData cData;
+
+  int choice = 0;
+  bool exit = false;
+  std::string message; // Message to encrypt or decrypt
+  while (!exit) {
+
+    std::string result;
+    switch (choice) {
+      case 1:
+        std::cout << "\nEncrypting...\n";
+
+        // Encrypt example from www.braingle.com
+        result = cData.Encrypt("WEAREDISCOVEREDFLEEATONCE");
+
+        // Take input for encrypting a message
+//        result = cData.Encrypt();
+
+        std::cout << "Encrypted message: " << result << std::endl;
+        exit = true;
+        break;
+
+      case 2:
+        std::cout << "\nDecrypting...\n";
+
+        // Encrypt, decrypt example from www.braingle.com
+        result = cData.Decrypt(cData.Encrypt("WEAREDISCOVEREDFLEEATONCE"));
+
+        // Take input for previously encrypted message to decrypt
+//        result = cData.Decrypt();
+
+        std::cout << "Decrypted message: " << result << std::endl;
+        exit = true;
+        break;
+
+      default:
+        std::cout << "What would you like to do?\n1. Encrypt\n2. Decrypt\n";
+        // Take input, handle it accordingly
+        // + https://www.cplusplus.com/forum/general/207458/
+        if (!(std::cin >> choice)) {
+          std::cout << "Invalid character input, choose an option below\n";
+        }
+        else if (choice != 1 && choice != 2) {
+          std::cout << "Incorrect option entered (" << choice << ")\n";
+        }
+        std::cin.clear();
+        std::cin.ignore();
+        break;
+    }
+
+  }
+
+  return 0;
+}

cpp/cryptography/columnar-transposition/lib-cipher.cpp

@@ -0,0 +1,127 @@
+/*##############################################################################
+## Author: Shaun Reed                                                         ##
+## Legal: All Content (c) 2021 Shaun Reed, all rights reserved                ##
+## About: An example of using columnar transposition cipher                   ##
+## + Using concept at www.braingle.com/brainteasers/codes/columnartrans.php   ##
+##                                                                            ##
+## Contact: shaunrd0@gmail.com  | URL: www.shaunreed.com | GitHub: shaunrd0   ##
+################################################################################
+*/
+
+#include "lib-cipher.hpp"
+
+// Initializes orderVect to determine order columns should be used
+void CipherData::InitOrder(std::string temp)
+{
+  // Create a temp value sorted lexicographically, remove duplicate characters
+  // https://en.cppreference.com/w/cpp/string/basic_string/operator_cmp
+  std::sort(temp.begin(), temp.end());
+  auto it = std::unique(temp.begin(), temp.end());
+  temp.erase(it, temp.end());
+
+  // Step through each character in lexicographic order
+  for (int i = 0; i < temp.size(); i++) {
+    // Check each character in the keyWord for the current lexicographic char
+    for (int j = 0; j < keyWord_.size(); j++) {
+      // If they are equal, push the index of the char in keyWord to orderVect
+      if (keyWord_[j] == temp[i]) {
+        orderVect_.push_back(j);
+      }
+    }
+  }
+
+}
+
+// Allows getting keyWord when using CipherData default ctor
+std::string CipherData::GetKey()
+{
+  std::string key;
+  std::cout << "Enter the keyword: ";
+  std::getline(std::cin, key);
+  std::cout << "Keyword entered: " << key << std::endl;
+  return key;
+}
+
+// Transpose a character matrix, using a vector of strings
+void CipherData::Transpose(const std::vector<std::string> &in,
+                           std::vector<std::string> &out)
+{
+  int cols = in[0].size();
+  // JIC some other row is larger than the first
+  for (const auto &row : in) cols = (row.size() > cols) ? row.size() : cols;
+  int rows = in.size();
+
+  out.resize(cols);
+
+  for (int i = 0; i < cols; i++) {
+    for (int j = 0; j < rows; j++) {
+      if (in[j].size() <= i) continue;
+      out[i] += in[j][i];
+    }
+  }
+}
+
+std::string CipherData::Encrypt(std::string message)
+{
+  // If no message was provided, ask for one
+  if (message.empty()) {
+    std::cout << "Input message to encrypt: ";
+    std::getline(std::cin, message);
+    std::cout << "Encrypting message \"" << message << "\"\n";
+  }
+  std::string encryptedMessage;
+  std::vector<std::string> rows;
+
+  // Split the message into rows equal to the length of our keyWord
+  for (size_t i = 0; i < message.size(); i+=keyWord_.size()) {
+    std::string substr = message.substr(i, keyWord_.size());
+    rows.push_back(substr);
+  }
+
+  // Transpose the matrix of characters
+  std::vector<std::string> transposed;
+  Transpose(rows, transposed);
+
+  // Append each row of the transposed matrix to our encryptedMessage
+  for (const auto &val : orderVect_) encryptedMessage += transposed[val];
+  return encryptedMessage;
+}
+
+std::string CipherData::Decrypt(std::string message)
+{
+  // If no message was provided, ask for one
+  if (message.empty()) {
+    std::cout << "Input message to decrypt: ";
+    std::getline(std::cin, message);
+    std::cout << "Decrypting message \"" << message << "\"\n";
+  }
+  std::string result;
+  std::vector<std::string> rows;
+
+  // Split the message into rows equal to the length of our keyWord
+  int rowLength = message.size() / keyWord_.size();
+  // If dividing message and keyword size has a remainder N
+  // + There will be N rows with +1 characters
+  int fullRows = message.size() % keyWord_.size();
+
+  rows.resize(orderVect_.size());
+  // Track the ending position after each substring is taken
+  int lastPos = 0;
+  for (int i = 0; i < orderVect_.size(); i++) {
+    // If we are assigning to any row < fullRows, it should have + 1 character
+    if (orderVect_[i] < fullRows) {
+      rows[orderVect_[i]] = message.substr(lastPos, rowLength + 1);
+      lastPos += rowLength + 1;
+    }
+    else {
+      rows[orderVect_[i]] = message.substr(lastPos, rowLength);
+      lastPos += rowLength;
+    }
+  }
+
+  std::vector<std::string> transposed;
+  Transpose(rows, transposed);
+
+  for (const auto &row : transposed) result += row;
+  return  result;
+}

cpp/cryptography/columnar-transposition/lib-cipher.hpp

@@ -0,0 +1,48 @@
+/*##############################################################################
+## Author: Shaun Reed                                                         ##
+## Legal: All Content (c) 2021 Shaun Reed, all rights reserved                ##
+## About: An example of using columnar transposition cipher                   ##
+## + Using concept at www.braingle.com/brainteasers/codes/columnartrans.php   ##
+##                                                                            ##
+## Contact: shaunrd0@gmail.com  | URL: www.shaunreed.com | GitHub: shaunrd0   ##
+################################################################################
+*/
+
+#ifndef COLUMNARTRANSPOSITION_LIB_CIPHER_HPP
+#define COLUMNARTRANSPOSITION_LIB_CIPHER_HPP
+
+#include <iostream>
+#include<algorithm>
+#include<vector>
+
+/******************************************************************************/
+// CipherData struct to hold data and methods related to encrypting / decrypting
+struct CipherData {
+  // Can't create this object without providing a keyWord to initialize order
+  explicit CipherData(std::string keyWord) : keyWord_(std::move(keyWord))
+  {
+    InitOrder(keyWord_);
+  }
+  CipherData() : keyWord_(GetKey()) { InitOrder(keyWord_);}
+
+  /****************************************************************************/
+  // Member functions
+
+  // Initializes orderVect, pass by value to create local copy of keyWord
+  void InitOrder(std::string temp);
+
+  static std::string GetKey();
+
+  static void
+  Transpose(const std::vector<std::string> &in, std::vector<std::string> &out);
+
+  // Default values for param allows calling with no message
+  std::string Encrypt(std::string message="");
+  std::string Decrypt(std::string message="");
+
+private:
+  std::string keyWord_;
+  std::vector<int> orderVect_;
+};
+
+#endif // COLUMNARTRANSPOSITION_LIB_CIPHER_HPP