bool signerAtsha204SoftSignMsg(MyMessage &msg) {
// If we cannot fit any signature in the message, refuse to sign it
if (mGetLength(msg) > MAX_PAYLOAD-2) {
DEBUG_SIGNING_PRINTBUF(F("Message too large"), NULL, 0);
return false;
}
// Calculate signature of message
mSetSigned(msg, 1); // make sure signing flag is set before signature is calculated
signerCalculateSignature(msg);
if (DO_WHITELIST(msg.destination)) {
// Salt the signature with the senders nodeId and the (hopefully) unique serial The Creator has provided
_signing_sha256.init();
for (int i=0; i<32; i++) _signing_sha256.write(_signing_hmac[i]);
_signing_sha256.write(msg.sender);
for (int i=0; i<SHA204_SERIAL_SZ; i++) _signing_sha256.write(_signing_node_serial_info[i]);
memcpy(_signing_hmac, _signing_sha256.result(), 32);
DEBUG_SIGNING_PRINTBUF(F("SHA256: "), _signing_hmac, 32);
DEBUG_SIGNING_PRINTBUF(F("Signature salted with serial"), NULL, 0);
}
// Overwrite the first byte in the signature with the signing identifier
_signing_hmac[0] = SIGNING_IDENTIFIER;
// Transfer as much signature data as the remaining space in the message permits
memcpy(&msg.data[mGetLength(msg)], _signing_hmac, MAX_PAYLOAD-mGetLength(msg));
DEBUG_SIGNING_PRINTBUF(F("Signature in message: "), (uint8_t*)&msg.data[mGetLength(msg)], MAX_PAYLOAD-mGetLength(msg));
return true;
}
// 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
}
