WIP cryptographic design

controller/fw/src/crypto.c

@@ -0,0 +1,48 @@
+
+#include <unistd.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <aes.h>
+
+#include "crypto.h"
+#include "simulation.h"
+
+void debug_hexdump(const char *name, uint8_t *buf, size_t len);
+void debug_hexdump(const char *name, uint8_t *buf, size_t len) {
+    DEBUG_PRINTN("%20s: ", name);
+    for (size_t i=0; i<len;) {
+        for (size_t j=0; j<8 && i<len; i++, j++)
+            DEBUG_PRINTN("%02x ", buf[i]);
+        DEBUG_PRINTN(" ");
+    }
+    DEBUG_PRINTN("\n");
+}
+
+int oob_message_received(uint8_t msg[static OOB_TRIGGER_LEN]) {
+    struct AES_ctx ctx;
+    uint8_t buf[crypto_sign_BYTES];
+
+    for (size_t serial=0; serial<PRESIG_STORE_SIZE; serial++) {
+        for (size_t dom=0; dom<_TRIGGER_DOMAIN_COUNT; dom++) {
+
+            DEBUG_PRINT("Trying domain %zd serial %zd", dom, serial);
+            debug_hexdump("oob_presig_iv", oob_presig_iv, sizeof(oob_presig_iv));
+
+            memcpy(buf, presig_store[dom][serial], crypto_sign_BYTES);
+            debug_hexdump("presig", buf, sizeof(buf));
+            AES_init_ctx_iv(&ctx, msg, oob_presig_iv);
+            AES_CBC_decrypt_buffer(&ctx, buf, crypto_sign_BYTES);
+            debug_hexdump("decrypted", buf, sizeof(buf));
+
+            if (!crypto_sign_verify_detached(buf, presig_messages[dom][serial], PRESIG_MSG_LEN, oob_trigger_pubkey)) {
+                oob_trigger_activated(dom, presig_first_serial + serial);
+                return 1;
+            }
+            DEBUG_PRINTN("\n");
+        }
+    }
+
+    return 0;
+}