Add method to load and save keyfiles

GCryptLib/include/GCrypt/Key.h

@@ -17,6 +17,12 @@ namespace Leonetienne::GCrypt {
       //! Will generate a random key from actual randomness (std::random_device)
       static Key Random();
 
+      //! Loads a keyfile
+      static Key LoadFromFile(const std::string& path);
+
+      //! Will save a keyfile
+      void WriteToFile(const std::string& path);
+
       Key();
       Key(const Key& k);
       Key(const Block& b);

GCryptLib/src/Key.cpp

@@ -3,6 +3,8 @@
 #include "GCrypt/Util.h"
 #include <random>
 #include <cassert>
+#include <sstream>
+#include <fstream>
 
 namespace Leonetienne::GCrypt {
 
@@ -30,6 +32,55 @@ namespace Leonetienne::GCrypt {
     return Key(Block(ss.str()));
   }
 
+  Key Key::LoadFromFile(const std::string& path) {
+    // Read this many chars
+    const std::size_t maxChars = BLOCK_SIZE / 8;
+
+    // Open ifilestream for keyfile
+    std::ifstream ifs(path, std::ios::in | std::ios::binary);
+
+    // Is the file open now? Or were there any issues...
+    if (!ifs.good()) {
+      throw std::runtime_error(std::string("Unable to open ifilestream for keyfile \"") + path + "\"! Aborting...");
+    }
+
+    // Read these chars to buffer
+    char* ckeyfileContent = new char[maxChars];
+    memset(ckeyfileContent, 0, maxChars * sizeof(char));
+    ifs.read(ckeyfileContent, maxChars);
+    ifs.close();
+
+    // Convert the buffer to a bit block of key size
+    std::stringstream ss;
+    for (std::size_t i = 0; i < maxChars; i++)
+      ss << std::bitset<8>(ckeyfileContent[i]);
+
+    Block key(ss.str());
+
+    // And delete the buffer
+    delete[] ckeyfileContent;
+    ckeyfileContent = nullptr;
+
+    // Return it
+    return key;
+  }
+
+  void Key::WriteToFile(const std::string& path) {
+    // Transform key to bytes
+    const std::string keybytes = BitsToBytes(to_string());
+
+    // Create an ofilestream
+    std::ofstream ofs(path, std::ios::out | std::ios::binary);
+
+    // Write the key
+    ofs.write(keybytes.data(), BLOCK_SIZE/8);
+
+    // Close the file handle
+    ofs.close();
+
+    return;
+  }
+
   Key::Key() : Block() {
   }