Add device id to support multiple remotes

include/example_config.h

@@ -12,6 +12,9 @@ constexpr uint32_t serialBaudRate = 115200;
 
 /* Keys */
 
+// The number of remote devices
+constexpr int remoteDeviceCount = 1;
+
 // The size of the symmetric keys used for signing and verifying messages
 constexpr size_t keySize = 32;
 

include/fresh.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <stdint.h>
+#include "config.h"
 
 /**
  * @brief The size of the message counter in bytes (uint32_t)
@@ -72,13 +73,15 @@ void prepareMessageCounterUsage();
  * 
  * @return The next counter to use by the remote 
  */
-uint32_t getNextMessageCounter();
+uint32_t getNextMessageCounter(uint8_t deviceId);
 
 /**
  * @brief Print info about the current message counter to the serial output
  * 
  */
-void printMessageCounter();
+void printMessageCounters();
+
+bool isDeviceIdValid(uint8_t deviceId);
 
 /**
  * @brief Check if a received counter is valid
@@ -90,7 +93,7 @@ void printMessageCounter();
  * @return true The counter is valid
  * @return false The counter belongs to an old message
  */
-bool isMessageCounterValid(uint32_t counter);
+bool isMessageCounterValid(uint32_t counter, uint8_t deviceId);
 
 /**
  * @brief Mark a counter of a message as used.
@@ -101,7 +104,7 @@ bool isMessageCounterValid(uint32_t counter);
  * 
  * @param counter The counter used in the last message.
  */
-void didUseMessageCounter(uint32_t counter);
+void didUseMessageCounter(uint32_t counter, uint8_t deviceId);
 
 /**
  * @brief Reset the message counter.
@@ -111,4 +114,4 @@ void didUseMessageCounter(uint32_t counter);
  * used for replay attacks.
  * 
  */
-void resetMessageCounter();
+void resetMessageCounters();

include/message.h

@@ -45,6 +45,11 @@ typedef struct {
      */
     uint32_t id;
 
+    /**
+     * @brief The id of the device sending the message
+     */
+    uint8_t device;
+
 } Message;
 
 /**
@@ -97,6 +102,7 @@ enum class SesameEvent {
     MessageTimeMismatch = 5,
     MessageCounterInvalid = 6,
     MessageAccepted = 7,
+    MessageDeviceInvalid = 8,
 };
 
 /**