Working on cpp project

Author: Ricky Ubuntu 24.04

cpp/dlms_crypto_tool/src/dlms_crypto_tool.cpp

@@ -0,0 +1,78 @@
+#include "dlms_crypto_tool.h"
+#include <openssl/evp.h>
+#include <openssl/rand.h>
+#include <sstream>
+#include <iomanip>
+#include <stdexcept>
+
+std::string generate_key()
+{
+
+    unsigned char key[16];
+
+    if(!RAND_bytes(key, sizeof(key)))
+    {
+
+        throw std::runtime_error("Failed to generate encryption key");
+
+    }
+
+    std::ostringstream oss;
+
+    for (int i = 0; i < 16; ++i)
+    {
+        
+        oss << std::hex << std::setw(2) << std::setfill('0') << (int)key[i];
+
+    }
+
+    return oss.str();
+    
+}
+
+std::vector<unsigned char> create_iv(const std::string& system_title, const std::string& frame_counter)
+{
+
+    std::vector<unsigned char> iv;
+
+    iv.insert(iv.end(), system_title.begin(), system_title.end());
+    iv.insert(iv.end(), frame_counter.begin(), frame_counter.end());
+
+    return iv;
+
+}
+
+std::string encrypt_apdu(const std::string& system_title, const std::string& frame_counter,
+                         const std::string& encryption_key, const std::string& additional_auth_data,
+                         const std::string& plaintext)
+{
+
+    // Prepare key and iv
+    unsigned char key[16];
+
+    std::vector<unsigned char> iv = create_iv(system_title, frame_counter);
+
+    if(iv.size() != 12)
+    {
+
+        throw std::invalid_argument("IV must be 12 bytes");
+
+    }
+
+    for (size_t i = 0; i < encryption_key.length() / 2; ++i)
+    {
+        
+        key[i] = std::stoi(encryption_key.substr(2 * i, 2), nullptr, 16);
+
+    }
+    
+    // Prepare plaitext and AAD
+    std::vector<unsigned char> plaintext_bytes(plaintext.begin(), plaintext.end());
+    std::vector<unsigned char> aad = SECURITY_HEADER_DATA + additional_auth_data; // TODO fix error
+
+    // Prepare buffers for ciphertext and tag
+    std::vector<unsigned char> cipheretext(plaintext_bytes.size());
+    unsigned char tag[16];
+
+    
+}

cpp/dlms_crypto_tool/src/dlms_crypto_tool.h

@@ -0,0 +1,32 @@
+#ifndef DLMS_CRYPTO_TOOL_H
+#define DLMS_CRYPTO_TOOL_H
+
+#include <string>
+#include <vector>
+
+// Security header constants
+const std::string SECURITY_HEADER_AUTH = "10";
+const std::string SECURITY_HEADER_DATA = "30";
+
+// Function to generate a random 16 byte encryption key
+std::string generate_key();
+
+// Function to create an IV by concatenating system_title and frame_counter
+std::vector<unsigned char> create_iv(const std::string& system_title, const std::string& frame_counter);
+
+// Function to encrypt an APDU message
+std::string encrypt_apdu(const std::string& system_title, const std::string& frame_counter,
+                         const std::string& encryption_key, const std::string& additional_auth_data,
+                         const std::string& plaintext);
+
+// Function to decrypt an APDU message
+std::string decrypt_apdu(const std::string& system_title, const std::string& frame_counter,
+                         const std::string& encryption_key, const std::string& additional_auth_data,
+                         const std::string& ciphertext_with_tag);
+
+// Function to authenticate an APDU
+std::string decrypt_apdu(const std::string& system_title, const std::string& frame_counter,
+    const std::string& encryption_key, const std::string& authentication_key,
+    const std::string& stoc);
+
+#endif // DLMS_CRYPTO_TOOL_H