C++ refactoring (#91)

TactilityCore/Source/crypt/Crypt.h

@@ -0,0 +1,69 @@
+/** @file secure.h
+ *
+ * @brief Hardware-bound encryption methods.
+ * @warning Enable secure boot and flash encryption to increase security.
+ *
+ * Offers AES 256 CBC encryption with built-in key.
+ * The key is built from data including:
+ *  - the internal factory MAC address
+ *  - random data stored in NVS
+ *
+ * It's important to use flash encryption to avoid an attacker to get
+ * access to your encrypted data. If flash encryption is disabled,
+ * someone can fetch the key from the partitions.
+ *
+ * See:
+ * https://docs.espressif.com/projects/esp-idf/en/latest/esp32/security/secure-boot-v2.html
+ * https://docs.espressif.com/projects/esp-idf/en/latest/esp32/security/flash-encryption.html
+ */
+#pragma once
+
+#include <cstdio>
+#include <cstdint>
+
+namespace tt::crypt {
+
+/**
+ * @brief Fills the IV with zeros and then creates an IV based on the input data.
+ * @param data input data
+ * @param data_length input data length
+ * @param iv output IV
+ */
+void get_iv_from_data(const void* data, size_t data_length, uint8_t iv[16]);
+
+/**
+* @brief Fills the IV with zeros and then creates an IV based on the input data.
+ * @param input input text
+ * @param iv output IV
+ */
+void get_iv_from_string(const char* input, uint8_t iv[16]);
+
+/**
+ * @brief Encrypt data.
+ *
+ * Important: Use flash encryption to increase security.
+ * Important: input and output data must be aligned to 16 bytes.
+ *
+ * @param iv the AES IV
+ * @param data_in input data
+ * @param data_out output data
+ * @param length data length, a multiple of 16
+ * @return the result of esp_aes_crypt_cbc() (MBEDTLS_ERR_*)
+ */
+int encrypt(const uint8_t iv[16], uint8_t* in_data, uint8_t* out_data, size_t length);
+
+/**
+ * @brief Decrypt data.
+ *
+ * Important: Use flash encryption to increase security.
+ * Important: input and output data must be aligned to 16 bytes.
+ *
+ * @param iv AES IV
+ * @param data_in input data
+ * @param data_out output data
+ * @param length data length, a multiple of 16
+ * @return the result of esp_aes_crypt_cbc() (MBEDTLS_ERR_*)
+ */
+int decrypt(const uint8_t iv[16], uint8_t* in_data, uint8_t* out_data, size_t length);
+
+} // namespace