Add 0x0026a custom AES-128-CMAC secure bootloader, Week 11a notebook, and README links

0x0026a_custom-bootloader/app/include/ir.h

@@ -0,0 +1,63 @@
+/**
+ * @file ir.h
+ * @brief Header for NEC IR receiver (decoder) API
+ * @author Kevin Thomas
+ * @date 2025
+ * 
+ * MIT License
+ * 
+ * Copyright (c) 2025 Kevin Thomas
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef IR_H
+#define IR_H
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Initialize the IR receiver GPIO
+ *
+ * Configures the given `pin` as an input with pull-up for the NEC IR receiver.
+ * Call this once during board initialization before calling `ir_getkey()`.
+ *
+ * @param pin GPIO pin number connected to IR receiver output
+ */
+void ir_init(uint8_t pin);
+
+/**
+ * @brief Blocking NEC IR decoder
+ *
+ * Blocks while waiting for a complete NEC frame. On success returns the
+ * decoded command byte (0..255). On timeout or protocol error returns -1.
+ *
+ * @return decoded command byte (0..255) or -1 on failure
+ */
+int ir_getkey(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // IR_H

0x0026a_custom-bootloader/app/include/led.h

@@ -0,0 +1,63 @@
+/**
+ * @file led.h
+ * @brief LED controller driven by decoded NEC IR commands.
+ * @author Kevin Thomas
+ * @date 2026
+ *
+ * MIT License
+ * Copyright (c) 2026 Kevin Thomas
+ */
+
+#ifndef LED_H
+#define LED_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief LED controller state for the three IR-controlled LEDs.
+ *
+ * Maps each logical LED (1-3) to its GPIO pin and remembers whether the
+ * LED is currently on. Build a default instance with led_default() and
+ * drive it with led_init() and led_handle_ir().
+ */
+typedef struct {
+    uint8_t led1_pin;
+    uint8_t led2_pin;
+    uint8_t led3_pin;
+    bool led1_state;
+    bool led2_state;
+    bool led3_state;
+} simple_led_ctrl_t;
+
+/**
+ * @brief Build the default three-LED configuration (pins 16-18, all off).
+ * @param void No parameters.
+ * @return simple_led_ctrl_t Default LED controller state.
+ */
+simple_led_ctrl_t led_default(void);
+
+/**
+ * @brief Configure the three LED GPIO pins as outputs.
+ * @param leds Pointer to the LED controller to initialize.
+ * @return void No return value.
+ */
+void led_init(simple_led_ctrl_t *leds);
+
+/**
+ * @brief Dispatch a decoded NEC command to the matching LED.
+ * @param leds Pointer to the LED controller to drive.
+ * @param key  Decoded NEC command byte, or a negative value to ignore.
+ * @return void No return value.
+ */
+void led_handle_ir(simple_led_ctrl_t *leds, int key);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // LED_H

0x0026a_custom-bootloader/app/include/secret.h

@@ -0,0 +1,29 @@
+/**
+ * @file secret.h
+ * @brief AES-128-CBC protected runtime banner for the application.
+ * @author Kevin Thomas
+ * @date 2026
+ *
+ * MIT License
+ * Copyright (c) 2026 Kevin Thomas
+ */
+
+#ifndef SECRET_H
+#define SECRET_H
+
+#include <stdint.h>
+
+/** @brief AES block size in bytes used by the runtime banner. */
+#define APP_AES_BLOCK 16U
+
+/** @brief Length in bytes of the encrypted runtime banner. */
+#define APP_BANNER_LEN 32U
+
+/**
+ * @brief Decrypt the embedded AES-128-CBC banner and print it.
+ * @param void No parameters.
+ * @return int Zero on success, non-zero when decryption fails.
+ */
+int secret_print_banner(void);
+
+#endif