#51 init mac component from config key

coordinator/config.lua

@@ -11,6 +11,11 @@ config.TRUSTED_RANGE = 0
 -- time in seconds (>= 2) before assuming a remote device is no longer active
 config.SV_TIMEOUT = 5
 config.API_TIMEOUT = 5
+-- facility authentication key (do NOT use one of your passwords)
+-- this enables verifying that messages are authentic
+-- all devices on the same network must use the same key
+-- message authentication codes require computing a hash on each message, so this can slow things down
+-- config.AUTH_KEY = "SCADAfacility123"
 
 -- expected number of reactor units, used only to require that number of unit monitors
 config.NUM_UNITS = 4

coordinator/coordinator.lua

@@ -183,7 +183,8 @@ local function log_dmesg(message, dmesg_tag, working)
         GRAPHICS = colors.green,
         SYSTEM = colors.cyan,
         BOOT = colors.blue,
-        COMMS = colors.purple
+        COMMS = colors.purple,
+        CRYPTO = colors.yellow
     }
 
     if working then
@@ -197,6 +198,7 @@ function coordinator.log_graphics(message) log_dmesg(message, "GRAPHICS") end
 function coordinator.log_sys(message) log_dmesg(message, "SYSTEM") end
 function coordinator.log_boot(message) log_dmesg(message, "BOOT") end
 function coordinator.log_comms(message) log_dmesg(message, "COMMS") end
+function coordinator.log_crypto(message) log_dmesg(message, "CRYPTO") end
 
 -- log a message for communications connecting, providing access to progress indication control functions
 ---@nodiscard

coordinator/startup.lua

@@ -31,6 +31,7 @@ local log_sys = coordinator.log_sys
 local log_boot = coordinator.log_boot
 local log_comms = coordinator.log_comms
 local log_comms_connecting = coordinator.log_comms_connecting
+local log_crypto = coordinator.log_crypto
 
 ----------------------------------------
 -- config validation
@@ -132,6 +133,12 @@ local function main()
     -- setup communications
     ----------------------------------------
 
+    -- message authentication init
+    if type(config.AUTH_KEY) == "string" then
+        local init_time = network.init_mac(config.AUTH_KEY)
+        log_crypto("HMAC init took " .. init_time .. "ms")
+    end
+
     -- get the communications modem
     local modem = ppm.get_wireless_modem()
     if modem == nil then