Slim down dummy signing driver.

libraries/MySensors/MySigningDriverDummy.cpp

@@ -36,51 +36,17 @@ static void DEBUG_DUMMY_PRINTBUF(char* str, uint8_t* buf, uint8_t sz)
 #endif
 
 MySigningDriverDummy::MySigningDriverDummy() : MySigningDriver() {
-	verification_ongoing = false;
-	current_nonce = 0;
 }
 
 bool MySigningDriverDummy::getNonce(MyMessage &msg) {
-	uint8_t nonce_buf[2];
-	nonce_buf[0] = SIGNING_IDENTIFIER;
-	// This is normally a buffer but for our minimal driver we use a single byte
-	// We at least use a new nonce for every session
-	nonce_buf[1] = ++current_nonce;
-	msg.set(nonce_buf, 2);
-	verification_ongoing = true;
-	timestamp = millis(); // Set timestamp to determine when to purge nonce
-	// Be a little fancy to handle turnover (prolong the time allowed to timeout after turnover)
-	// Note that if message is "too" quick, and arrives before turnover, it will be rejected
-	// but this is consider such a rare case that it is accepted and rejects are 'safe'
-	if (timestamp + VERIFICATION_TIMEOUT_MS < millis()) timestamp = 0;
 	return true;
 }
 
 bool MySigningDriverDummy::checkTimer() {
-	if (verification_ongoing) {
-		if (millis() < timestamp || millis() > timestamp + VERIFICATION_TIMEOUT_MS) {
-			DEBUG_DUMMY_PRINTLN("Verification timeout");
-			// Purge nonce
-			current_nonce = 0; // purge nonce when used
-			verification_ongoing = false;
-			return false; 
-		}
-	}
 	return true;
 }
 
 bool MySigningDriverDummy::putNonce(MyMessage &msg) {
-	if (mGetLength(msg) != 2) {
-		DEBUG_DUMMY_PRINTLN("Incoming nonce with incorrect size");
-		return false; // We require a signing identifier and a 1byte nonce
-	}
-
-	if (((uint8_t*)msg.getCustom())[0] != SIGNING_IDENTIFIER) {
-		DEBUG_DUMMY_PRINTLN("Incorrect signing identifier");
-		return false; 
-	}
-
-	current_nonce = ((uint8_t*)msg.getCustom())[1];
 	return true;
 }
 
@@ -90,54 +56,15 @@ bool MySigningDriverDummy::signMsg(MyMessage &msg) {
 		DEBUG_DUMMY_PRINTLN("Cannot fit any signature to this message");
 		return false; 
 	}
-
-	// Calculate signature of message
 	mSetSigned(msg, 1); // make sure signing flag is set before signature is calculated
-	DEBUG_DUMMY_PRINTBUF("Message to sign:", (uint8_t*)&msg.data[1-HEADER_SIZE], MAX_MESSAGE_LENGTH-1-(MAX_PAYLOAD-mGetLength(msg)));
-	uint8_t signature = msg.data[0] ^ current_nonce;
 	msg.data[mGetLength(msg)] = SIGNING_IDENTIFIER; // Add signing identifier
-	msg.data[mGetLength(msg)+1] = signature;
-	current_nonce = 0; // purge nonce when used
 	return true;
 }
 
 bool MySigningDriverDummy::verifyMsg(MyMessage &msg) {
-	if (!verification_ongoing) {
+	if (msg.data[mGetLength(msg)] != SIGNING_IDENTIFIER)
-		DEBUG_DUMMY_PRINTLN("No active verification session");
+		return false;
-		return false; 
+	else
-	} else {
+		return true;
-		// Make sure we have not expired
-		if (!checkTimer()) {
-			return false; 
-		}
-
-		verification_ongoing = false;
-
-		if (msg.data[mGetLength(msg)] != SIGNING_IDENTIFIER) {
-			DEBUG_DUMMY_PRINTLN("Incorrect signing identifier");
-			return false; 
-		}
-
-		DEBUG_DUMMY_PRINTBUF("Message to verify:", (uint8_t*)&msg.data[1-HEADER_SIZE], MAX_MESSAGE_LENGTH-1-(MAX_PAYLOAD-mGetLength(msg)));
-		DEBUG_DUMMY_PRINTBUF("Signature in message:", (uint8_t*)&msg.data[mGetLength(msg)], 2);
-
-		// The dummy signing is the nonce XOR the first payload byte,
-		// so we "verify" by redoing that calculation with the nonce we transmitted
-		// Message without a payload this implementation always accepts as signed and messages that cannot
-		// fit a signature are also accepted as signed
-		if (mGetLength(msg) && mGetLength(msg) < MAX_PAYLOAD-2) {
-			uint8_t signature = msg.data[0] ^ current_nonce;
-			if (msg.data[mGetLength(msg)+1] != signature) {
-				DEBUG_DUMMY_PRINTBUF("Signature bad. Calculated signature:", &signature, 1);
-				return false;
-			} else {
-				DEBUG_DUMMY_PRINTLN("Signature ok");
-				return true;
-			}
-		} else {
-			DEBUG_DUMMY_PRINTLN("No signature in message");
-			return false; 
-		}
-	}
 }
 #endif

libraries/MySensors/MySigningDriverDummy.h

@@ -10,11 +10,8 @@
 #include "MySigningDriver.h"
 #include <stdint.h>
 
-// The dummy signing driver implements the most rudimentary form of signing
+// The dummy signing driver that can be used for nodes
-// No pre-shared key is used, nonce is simply incremeted each turn and signature
+// not requiring signing
-// is only calculated on the fist byte using data XOR nonce.
-// This driver is intended for library debugging and sensor network integrity
-// verification (signed messages will force the radio to transmit all 32 bytes of data).
 // It does check SIGNING_IDENTIFIER byte to avoid illegal mixing of signing back-ends in
 // the network (as seen by this node) and it does verify proper execution order on the API.
 // The dummy driver rejects all other back-ends.
@@ -27,10 +24,6 @@ public:
 	bool putNonce(MyMessage &msg);
 	bool signMsg(MyMessage &msg);
 	bool verifyMsg(MyMessage &msg);
-private:
-	unsigned long timestamp;
-	bool verification_ongoing;
-	uint8_t current_nonce;
 };
 
 #endif