// Helper function to centralize signing/verification exceptions
static bool skipSign(MyMessage &msg)
{
bool ret;
if (mGetAck(msg)) {
SIGN_DEBUG(PSTR("Skipping security for ACK on command %d type %d\n"), mGetCommand(msg), msg.type);
ret = true;
} else if (mGetCommand(msg) == C_INTERNAL &&
(msg.type == I_NONCE_REQUEST || msg.type == I_NONCE_RESPONSE ||
msg.type == I_SIGNING_PRESENTATION ||
msg.type == I_ID_REQUEST || msg.type == I_ID_RESPONSE ||
msg.type == I_FIND_PARENT_REQUEST || msg.type == I_FIND_PARENT_RESPONSE ||
msg.type == I_HEARTBEAT_REQUEST || msg.type == I_HEARTBEAT_RESPONSE ||
msg.type == I_PING || msg.type == I_PONG ||
msg.type == I_REGISTRATION_REQUEST || msg.type == I_DISCOVER_REQUEST ||
msg.type == I_DISCOVER_RESPONSE )) {
SIGN_DEBUG(PSTR("Skipping security for command %d type %d\n"), mGetCommand(msg), msg.type);
ret = true;
} else if (mGetCommand(msg) == C_STREAM &&
(msg.type == ST_FIRMWARE_REQUEST || msg.type == ST_FIRMWARE_RESPONSE ||
msg.type == ST_SOUND || msg.type == ST_IMAGE)) {
SIGN_DEBUG(PSTR("Skipping security for command %d type %d\n"), mGetCommand(msg), msg.type);
ret = true;
} else {
ret = false;
}
return ret;
}
// Helper to process nonce request mesages
static bool signerInternalProcessNonceRequest(MyMessage &msg)
{
#if defined(MY_SIGNING_FEATURE)
#if defined(MY_NODE_LOCK_FEATURE)
nof_nonce_requests++;
SIGN_DEBUG(PSTR("Nonce requests left until lockdown: %d\n"),
MY_NODE_LOCK_COUNTER_MAX-nof_nonce_requests);
if (nof_nonce_requests >= MY_NODE_LOCK_COUNTER_MAX) {
_nodeLock("TMNR"); //Too many nonces requested
}
#endif // MY_NODE_LOCK_FEATURE
if (signerBackendGetNonce(msg)) {
if (!_sendRoute(build(msg, msg.sender, NODE_SENSOR_ID, C_INTERNAL, I_NONCE_RESPONSE))) {
SIGN_DEBUG(PSTR("Failed to transmit nonce!\n"));
} else {
SIGN_DEBUG(PSTR("Transmitted nonce\n"));
}
} else {
SIGN_DEBUG(PSTR("Failed to generate nonce!\n"));
}
#else // not MY_SIGNING_FEATURE
(void)msg;
SIGN_DEBUG(PSTR("Received nonce request, but signing is not supported (message ignored)\n"));
#endif // MY_SIGNING_FEATURE
return true; // No need to further process I_NONCE_REQUEST
}
bool signerVerifyMsg(MyMessage &msg)
{
bool verificationResult = true;
// Before processing message, reject unsigned messages if signing is required and check signature
// (if it is signed and addressed to us)
// Note that we do not care at all about any signature found if we do not require signing
#if defined(MY_SIGNING_FEATURE) && defined(MY_SIGNING_REQUEST_SIGNATURES)
// If we are a node, or we are a gateway and the sender require signatures (or just a strict gw)
// and we are the destination...
#if defined(MY_SIGNING_GW_REQUEST_SIGNATURES_FROM_ALL)
if (msg.destination == getNodeId()) {
#else
if ((!MY_IS_GATEWAY || DO_SIGN(msg.sender)) && msg.destination == getNodeId()) {
#endif
// Internal messages of certain types are not verified
if (skipSign(msg)) {
verificationResult = true;
} else if (!mGetSigned(msg)) {
// Got unsigned message that should have been signed
SIGN_DEBUG(PSTR("Message is not signed, but it should have been!\n"));
verificationResult = false;
} else {
if (!signerBackendVerifyMsg(msg)) {
SIGN_DEBUG(PSTR("Signature verification failed!\n"));
verificationResult = false;
}
#if defined(MY_NODE_LOCK_FEATURE)
if (verificationResult) {
// On successful verification, clear lock counters
nof_nonce_requests = 0;
nof_failed_verifications = 0;
} else {
nof_failed_verifications++;
SIGN_DEBUG(PSTR("Failed verification attempts left until lockdown: %d\n"),
MY_NODE_LOCK_COUNTER_MAX-nof_failed_verifications);
if (nof_failed_verifications >= MY_NODE_LOCK_COUNTER_MAX) {
_nodeLock("TMFV"); //Too many failed verifications
}
}
#endif
mSetSigned(msg,0); // Clear the sign-flag now as verification is completed
}
}
#else
(void)msg;
#endif // MY_SIGNING_REQUEST_SIGNATURES
return verificationResult;
}
static uint8_t sha256_hash[32];
Sha256Class _soft_sha256;
void signerSha256Init(void)
{
memset(sha256_hash, 0, 32);
_soft_sha256.init();
}
// Helper to process nonce response mesages
static bool signerInternalProcessNonceResponse(MyMessage &msg)
{
#if defined(MY_SIGNING_FEATURE)
// Proceed with signing if nonce has been received
SIGN_DEBUG(PSTR("Nonce received from %d.\n"), msg.sender);
if (msg.sender != _msgSign.destination) {
SIGN_DEBUG(PSTR("Nonce did not come from the destination (%d) of the message to be signed! "
"It came from %d.\n"), _msgSign.destination, msg.sender);
SIGN_DEBUG(PSTR("Silently discarding this nonce\n"));
} else {
SIGN_DEBUG(PSTR("Proceeding with signing...\n"));
signerBackendPutNonce(msg);
if (!signerBackendSignMsg(_msgSign)) {
SIGN_DEBUG(PSTR("Failed to sign message!\n"));
} else {
SIGN_DEBUG(PSTR("Message signed\n"));
_signingNonceStatus = SIGN_OK; // _msgSign now contains the signed message pending transmission
}
}
#else
(void)msg;
SIGN_DEBUG(PSTR("Received nonce response, but signing is not supported (message ignored)\n"));
#endif
return true; // No need to further process I_NONCE_RESPONSE
}
bool signerSignMsg(MyMessage &msg)
{
bool ret;
#if defined(MY_SIGNING_FEATURE)
// If destination is known to require signed messages and we are the sender,
// sign this message unless it is identified as an exception
if (DO_SIGN(msg.destination) && msg.sender == getNodeId()) {
if (skipSign(msg)) {
ret = true;
} else {
// Send nonce-request
_signingNonceStatus=SIGN_WAITING_FOR_NONCE;
if (!_sendRoute(build(_msgSign, msg.destination, msg.sensor, C_INTERNAL,
I_NONCE_REQUEST).set(""))) {
SIGN_DEBUG(PSTR("Failed to transmit nonce request!\n"));
ret = false;
} else {
SIGN_DEBUG(PSTR("Nonce requested from %d. Waiting...\n"), msg.destination);
// We have to wait for the nonce to arrive before we can sign our original message
// Other messages could come in-between. We trust _process() takes care of them
unsigned long enter = hwMillis();
_msgSign = msg; // Copy the message to sign since message buffer might be touched in _process()
while (hwMillis() - enter < MY_VERIFICATION_TIMEOUT_MS &&
_signingNonceStatus==SIGN_WAITING_FOR_NONCE) {
_process();
}
if (hwMillis() - enter > MY_VERIFICATION_TIMEOUT_MS) {
SIGN_DEBUG(PSTR("Timeout waiting for nonce!\n"));
ret = false;
} else {
if (_signingNonceStatus == SIGN_OK) {
// process() received a nonce and signerProcessInternal successfully signed the message
msg = _msgSign; // Write the signed message back
SIGN_DEBUG(PSTR("Message to send has been signed\n"));
ret = true;
// After this point, only the 'last' member of the message structure is allowed to be altered if the
// message has been signed, or signature will become invalid and the message rejected by the receiver
} else {
SIGN_DEBUG(PSTR("Message to send could not be signed!\n"));
ret = false;
}
}
}
}
} else if (getNodeId() == msg.sender) {
mSetSigned(msg, 0); // Message is not supposed to be signed, make sure it is marked unsigned
SIGN_DEBUG(PSTR("Will not sign message for destination %d as it does not require it\n"),
msg.destination);
ret = true;
} else {
SIGN_DEBUG(PSTR("Will not sign message since it was from %d and we are %d\n"), msg.sender,
getNodeId());
ret = true;
}
#else
(void)msg;
ret = true;
#endif // MY_SIGNING_FEATURE
return ret;
}
void signerPresentation(MyMessage &msg, uint8_t destination)
{
prepareSigningPresentation(msg, destination);
#if defined(MY_SIGNING_REQUEST_SIGNATURES)
msg.data[1] |= SIGNING_PRESENTATION_REQUIRE_SIGNATURES;
SIGN_DEBUG(PSTR("Signing required\n"));
#endif
#if defined(MY_SIGNING_NODE_WHITELISTING)
msg.data[1] |= SIGNING_PRESENTATION_REQUIRE_WHITELISTING;
SIGN_DEBUG(PSTR("Whitelisting required\n"));
#endif
if (!_sendRoute(msg)) {
SIGN_DEBUG(PSTR("Failed to transmit signing presentation!\n"));
}
if (destination == GATEWAY_ADDRESS) {
SIGN_DEBUG(PSTR("Waiting for GW to send signing preferences...\n"));
wait(2000, C_INTERNAL, I_SIGNING_PRESENTATION);
}
}
// Helper to process presentation mesages
static bool signerInternalProcessPresentation(MyMessage &msg)
{
const uint8_t sender = msg.sender;
#if defined(MY_SIGNING_FEATURE)
if (msg.data[0] != SIGNING_PRESENTATION_VERSION_1) {
SIGN_DEBUG(PSTR("Unsupported signing presentation version (%d)!\n"), msg.data[0]);
return true; // Just drop this presentation message
}
// We only handle version 1 here...
if (msg.data[1] & SIGNING_PRESENTATION_REQUIRE_SIGNATURES) {
// We received an indicator that the sender require us to sign all messages we send to it
SIGN_DEBUG(PSTR("Mark node %d as one that require signed messages\n"), sender);
SET_SIGN(sender);
} else {
// We received an indicator that the sender does not require us to sign all messages we send to it
SIGN_DEBUG(PSTR("Mark node %d as one that do not require signed messages\n"), sender);
CLEAR_SIGN(sender);
}
if (msg.data[1] & SIGNING_PRESENTATION_REQUIRE_WHITELISTING) {
// We received an indicator that the sender require us to salt signatures with serial
SIGN_DEBUG(PSTR("Mark node %d as one that require whitelisting\n"), sender);
SET_WHITELIST(sender);
} else {
// We received an indicator that the sender does not require us to sign all messages we send to it
SIGN_DEBUG(PSTR("Mark node %d as one that do not require whitelisting\n"), sender);
CLEAR_WHITELIST(sender);
}
// Save updated tables
hwWriteConfigBlock((void*)_doSign, (void*)EEPROM_SIGNING_REQUIREMENT_TABLE_ADDRESS,
sizeof(_doSign));
hwWriteConfigBlock((void*)_doWhitelist, (void*)EEPROM_WHITELIST_REQUIREMENT_TABLE_ADDRESS,
sizeof(_doWhitelist));
// Inform sender about our preference if we are a gateway, but only require signing if the sender
// required signing unless we explicitly configure it to
#if defined(MY_GATEWAY_FEATURE)
prepareSigningPresentation(msg, sender);
#if defined(MY_SIGNING_REQUEST_SIGNATURES)
#if defined(MY_SIGNING_GW_REQUEST_SIGNATURES_FROM_ALL)
msg.data[1] |= SIGNING_PRESENTATION_REQUIRE_SIGNATURES;
#else
if (DO_SIGN(sender)) {
msg.data[1] |= SIGNING_PRESENTATION_REQUIRE_SIGNATURES;
}
#endif
#endif // MY_SIGNING_REQUEST_SIGNATURES
#if defined(MY_SIGNING_NODE_WHITELISTING)
#if defined(MY_SIGNING_GW_REQUEST_SIGNATURES_FROM_ALL)
msg.data[1] |= SIGNING_PRESENTATION_REQUIRE_WHITELISTING;
#else
if (DO_WHITELIST(sender)) {
msg.data[1] |= SIGNING_PRESENTATION_REQUIRE_WHITELISTING;
}
#endif
#endif // MY_SIGNING_NODE_WHITELISTING
if (msg.data[1] & SIGNING_PRESENTATION_REQUIRE_SIGNATURES) {
SIGN_DEBUG(PSTR("Informing node %d that we require signatures\n"), sender);
} else {
SIGN_DEBUG(PSTR("Informing node %d that we do not require signatures\n"), sender);
}
if (msg.data[1] & SIGNING_PRESENTATION_REQUIRE_WHITELISTING) {
SIGN_DEBUG(PSTR("Informing node %d that we require whitelisting\n"), sender);
} else {
SIGN_DEBUG(PSTR("Informing node %d that we do not require whitelisting\n"), sender);
}
if (!_sendRoute(msg)) {
SIGN_DEBUG(PSTR("Failed to transmit signing presentation!\n"));
}
#endif // MY_GATEWAY_FEATURE
#else // not MY_SIGNING_FEATURE
#if defined(MY_GATEWAY_FEATURE)
// If we act as gateway and do not have the signing feature and receive a signing request we still
// need to do make sure the requester does not believe the gateway still require signatures
prepareSigningPresentation(msg, sender);
SIGN_DEBUG(
PSTR("Informing node %d that we do not require signatures because we do not support it\n"),
sender);
if (!_sendRoute(msg)) {
SIGN_DEBUG(PSTR("Failed to transmit signing presentation!\n"));
}
#else // not MY_GATEWAY_FEATURE
// If we act as a node and do not have the signing feature then we just silently drop any signing
// presentation messages received
(void)msg;
(void)sender;
SIGN_DEBUG(PSTR("Received signing presentation, but signing is not supported (message ignored)\n"));
#endif // not MY_GATEWAY_FEATURE
#endif // not MY_SIGNING_FEATURE
return true; // No need to further process I_SIGNING_PRESENTATION
}
// Helper function to centralize signing/verification exceptions
static bool skipSign(MyMessage &msg) {
if mGetAck(msg) {
SIGN_DEBUG(PSTR("Skipping security for ACK on command %d type %d\n"), mGetCommand(msg), msg.type);
return true;
} else if (mGetCommand(msg) == C_INTERNAL &&
