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#include "TransportKeyStore.h"
#include <SHA256.h>
uint16_t TransportKey::calcTransportCode(const mesh::Packet* packet) const {
uint16_t code;
SHA256 sha;
sha.resetHMAC(key, sizeof(key));
uint8_t type = packet->getPayloadType();
sha.update(&type, 1);
sha.update(packet->payload, packet->payload_len);
sha.finalizeHMAC(key, sizeof(key), &code, 2);
if (code == 0) { // reserve codes 0000 and FFFF
code++;
} else if (code == 0xFFFF) {
code--;
}
return code;
}
bool TransportKey::isNull() const {
for (int i = 0; i < sizeof(key); i++) {
if (key[i]) return false;
}
return true; // key is all zeroes
}
void TransportKeyStore::putCache(uint16_t id, const TransportKey& key) {
if (num_cache < MAX_TKS_ENTRIES) {
cache_ids[num_cache] = id;
cache_keys[num_cache] = key;
num_cache++;
} else {
// TODO: evict oldest cache entry
}
}
void TransportKeyStore::getAutoKeyFor(uint16_t id, const char* name, TransportKey& dest) {
for (int i = 0; i < num_cache; i++) { // first, check cache
if (cache_ids[i] == id) { // cache hit!
dest = cache_keys[i];
return;
}
}
// calc key for publicly-known hashtag region name
SHA256 sha;
sha.update(name, strlen(name));
sha.finalize(&dest.key, sizeof(dest.key));
putCache(id, dest);
}
int TransportKeyStore::loadKeysFor(uint16_t id, TransportKey keys[], int max_num) {
int n = 0;
for (int i = 0; i < num_cache && n < max_num; i++) { // first, check cache
if (cache_ids[i] == id) {
keys[n++] = cache_keys[i];
}
}
if (n > 0) return n; // cache hit!
// TODO: retrieve from difficult-to-copy keystore
// store in cache (if room)
for (int i = 0; i < n; i++) {
putCache(id, keys[i]);
}
return n;
}
bool TransportKeyStore::saveKeysFor(uint16_t id, const TransportKey keys[], int num) {
invalidateCache();
// TODO: update hardware keystore
return false; // failed
}
bool TransportKeyStore::removeKeys(uint16_t id) {
invalidateCache();
// TODO: remove from hardware keystore
return false; // failed
}
bool TransportKeyStore::clear() {
invalidateCache();
// TODO: clear hardware keystore
return false; // failed
}
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