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Whitelisting support in signing backend

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Whitelisting is enabled using MY_SECURE_NODE_WHITELISTING in MyConfig.h.
The whitelist is provided in backend constructors.
See the SecureActuator example for a typical usecase.
This commit is contained in:
Patrick Fallberg
2015-03-16 20:21:05 +01:00
parent cf31edcb81
commit f295ef2961
7 changed files with 177 additions and 35 deletions
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libraries/MySensors/MySigningAtsha204.cpp
+47 -21
View File
@@ -36,10 +36,18 @@ static void DEBUG_ATSHA_PRINTBUF(char* str, uint8_t* buf, uint8_t sz)
#endif
MySigningAtsha204::MySigningAtsha204(bool requestSignatures, uint8_t atshaPin)
MySigningAtsha204::MySigningAtsha204(bool requestSignatures,
#ifdef MY_SECURE_NODE_WHITELISTING
uint8_t nof_whitelist_entries, const whitelist_entry_t* the_whitelist,
#endif
uint8_t atshaPin)
:
MySigning(requestSignatures),
atsha204(atshaPin),
#ifdef MY_SECURE_NODE_WHITELISTING
whitelist(the_whitelist),
whitlist_sz(nof_whitelist_entries),
#endif
verification_ongoing(false)
{
}
@@ -50,21 +58,14 @@ bool MySigningAtsha204::getNonce(MyMessage &msg) {
// We used a basic whitening technique that takes the first byte of a new random value and builds up a 32-byte random value
// This 32-byte random value is then hashed (SHA256) to produce the resulting nonce
for (int i = 0; i < 32; i++) {
// Wake device before starting operations
if (atsha204.sha204c_wakeup(rx_buffer) != SHA204_SUCCESS) {
DEBUG_ATSHA_PRINTLN("Failed to wake device");
return false;
}
if (atsha204.sha204m_execute(SHA204_RANDOM, RANDOM_NO_SEED_UPDATE, 0, 0, NULL,
RANDOM_COUNT, tx_buffer, RANDOM_RSP_SIZE, rx_buffer) != SHA204_SUCCESS) {
DEBUG_ATSHA_PRINTLN("Failed to generate nonce");
return false;
}
atsha204.sha204c_sleep();
current_nonce[i] = rx_buffer[SHA204_BUFFER_POS_DATA];
}
pRnd = sha256(current_nonce, 32);
atsha204.sha204c_sleep();
if (!pRnd) {
DEBUG_ATSHA_PRINTLN("Failed to hash random value");
@@ -134,6 +135,19 @@ bool MySigningAtsha204::signMsg(MyMessage &msg) {
return false;
}
#ifdef MY_SECURE_NODE_WHITELISTING
// Salt the signature with the senders nodeId and the unique serial of the ATSHA device
memcpy(current_nonce, &rx_buffer[SHA204_BUFFER_POS_DATA], 32); // We can reuse the nonce buffer now since it is no longer needed
current_nonce[32] = msg.sender;
(void)atsha204.getSerialNumber(&current_nonce[33]);
(void)sha256(current_nonce, 32+1+SHA204_SERIAL_SZ); // we can 'void' sha256 because the hash is already put in the correct place
memset(current_nonce, 0xAA, NONCE_NUMIN_SIZE_PASSTHROUGH);
DEBUG_ATSHA_PRINTLN("Signature salted");
#endif
// Overwrite the first byte in the signature with the signing identifier
rx_buffer[SHA204_BUFFER_POS_DATA] = SIGNING_IDENTIFIER;
// Transfer as much signature data as the remaining space in the message permits
memcpy(&msg.data[mGetLength(msg)], &rx_buffer[SHA204_BUFFER_POS_DATA], MAX_PAYLOAD-mGetLength(msg));
@@ -166,9 +180,29 @@ bool MySigningAtsha204::verifyMsg(MyMessage &msg) {
return false;
}
#ifdef MY_SECURE_NODE_WHITELISTING
// Look up the senders nodeId in our whitelist and salt the signature with that data
for (int j=0; j < whitlist_sz; j++) {
if (whitelist[j].nodeId == msg.sender) {
DEBUG_ATSHA_PRINTLN("Sender found in whitelist");
memcpy(current_nonce, &rx_buffer[SHA204_BUFFER_POS_DATA], 32); // We can reuse the nonce buffer now since it is no longer needed
current_nonce[32] = msg.sender;
memcpy(&current_nonce[33], whitelist[j].serial, SHA204_SERIAL_SZ);
(void)sha256(current_nonce, 32+1+SHA204_SERIAL_SZ); // we can 'void' sha256 because the hash is already put in the correct place
break;
}
}
#endif
// Overwrite the first byte in the signature with the signing identifier
rx_buffer[SHA204_BUFFER_POS_DATA] = SIGNING_IDENTIFIER;
// Compare the caluclated signature with the provided signature
if (memcmp(&msg.data[mGetLength(msg)], &rx_buffer[SHA204_BUFFER_POS_DATA], MAX_PAYLOAD-mGetLength(msg))) {
DEBUG_ATSHA_PRINTBUF("Signature bad. Calculated signature:", &rx_buffer[SHA204_BUFFER_POS_DATA], MAX_PAYLOAD-mGetLength(msg));
#ifdef MY_SECURE_NODE_WHITELISTING
DEBUG_ATSHA_PRINTLN("Is the sender whitelisted?");
#endif
return false;
} else {
DEBUG_ATSHA_PRINTLN("Signature ok");
@@ -182,9 +216,6 @@ bool MySigningAtsha204::calculateSignature(MyMessage &msg) {
memset(temp_message, 0, 32);
memcpy(temp_message, (uint8_t*)&msg.data[1-HEADER_SIZE], MAX_MESSAGE_LENGTH-1-(MAX_PAYLOAD-mGetLength(msg)));
// Wake device before starting operations
if (atsha204.sha204c_wakeup(rx_buffer) != SHA204_SUCCESS) return false;
// Program the data to sign into the ATSHA204
if (atsha204.sha204m_execute(SHA204_WRITE, SHA204_ZONE_DATA | SHA204_ZONE_COUNT_FLAG, 8 << 3, 32, temp_message,
WRITE_COUNT_LONG, tx_buffer, WRITE_RSP_SIZE, rx_buffer) != SHA204_SUCCESS) {
@@ -221,21 +252,12 @@ bool MySigningAtsha204::calculateSignature(MyMessage &msg) {
// Put device back to sleep
atsha204.sha204c_sleep();
// Overwrite the first byte in the signature with the signing identifier
rx_buffer[SHA204_BUFFER_POS_DATA] = SIGNING_IDENTIFIER;
DEBUG_ATSHA_PRINTBUF("HMAC:", &rx_buffer[SHA204_BUFFER_POS_DATA], 32);
return true; // We return with the signature in rx_buffer[SHA204_BUFFER_POS_DATA]
}
// Helper to calculate a generic SHA256 digest of provided buffer (returned in rx_buffer[SHA204_BUFFER_POS_DATA]) (only supports one block)
uint8_t* MySigningAtsha204::sha256(const uint8_t* data, size_t sz) {
// Wake device before starting operations
if (atsha204.sha204c_wakeup(rx_buffer) != SHA204_SUCCESS) {
DEBUG_ATSHA_PRINTLN("Failed to wake device");
return NULL;
}
// Initiate SHA256 calculator
if (atsha204.sha204m_execute(SHA204_SHA, SHA_INIT, 0, 0, NULL,
SHA_COUNT_SHORT, tx_buffer, SHA_RSP_SIZE_SHORT, rx_buffer) != SHA204_SUCCESS) {
@@ -250,12 +272,16 @@ uint8_t* MySigningAtsha204::sha256(const uint8_t* data, size_t sz) {
// Write length data to the last bytes
temp_message[SHA_MSG_SIZE-2] = (sz >> 5);
temp_message[SHA_MSG_SIZE-1] = (sz << 3);
DEBUG_ATSHA_PRINTBUF("Data to hash (padded):", temp_message, SHA_MSG_SIZE);
DEBUG_ATSHA_PRINTBUF("Data to hash:", temp_message, SHA_MSG_SIZE);
if (atsha204.sha204m_execute(SHA204_SHA, SHA_CALC, 0, SHA_MSG_SIZE, temp_message,
SHA_COUNT_LONG, tx_buffer, SHA_RSP_SIZE_LONG, rx_buffer) != SHA204_SUCCESS) {
DEBUG_ATSHA_PRINTLN("Failed to calculate sha256");
return NULL;
}
// Put device back to sleep
atsha204.sha204c_sleep();
DEBUG_ATSHA_PRINTBUF("SHA:", &rx_buffer[SHA204_BUFFER_POS_DATA], 32);
return &rx_buffer[SHA204_BUFFER_POS_DATA];
}