implement decrypt method

src/Encryptor.cpp

@@ -36,8 +36,28 @@ uint64_t Encryptor::blowfish_encrypt(std::vector<char> &input_buf,
   return input_buf.size();
 }
 
-uint64_t Encryptor::blowfish_decrypt(std::vector<char> const &input_buf,
-                            std::string const &key, uint64_t in_size){
-                              
-                            }
+uint64_t Encryptor::blowfish_decrypt(std::vector<char> &input_buf,
+                                     std::string const &key, uint64_t in_size) {
+  uint32_t L = 0, R = 0;
+  int block_size = sizeof(uint32_t);
+  Blowfish blowfish(key);
+
+  for (size_t i = 0; i < in_size; i += (block_size * 2)) {
+    L = str_to_uint32(
+        std::string(input_buf.data() + i, input_buf.data() + i + block_size),
+        block_size);
+    R = str_to_uint32(std::string(input_buf.data() + i + block_size,
+                                  input_buf.data() + i + 2 * block_size),
+                      block_size);
+    blowfish.decrypt(L, R);
+    std::string block = uint32_to_str(L, block_size);
+    block += uint32_to_str(R, block_size);
+    int j = i;
+    std::for_each(block.begin(), block.end(), [&](char b) {
+      input_buf[j] = b;
+      j++;
+    });
+  }
+  return input_buf.size();
+}
 } // namespace krypto