Reduce key duplication by enabling hardware RNG (#8803)

* Reduce key duplication by enabling hardware RNG

* Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Apply suggestion from @Copilot

Use micros() for worst case random seed for nrf52

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Minor cleanup, remove dead code and clarify comment

* trunk

* Add useRadioEntropy bool, default false.

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Jonathan Bennett <jbennett@incomsystems.biz>

src/platform/nrf52/main-nrf52.cpp

@@ -17,6 +17,7 @@
 #include <nrfx_wdt.h>
 #include <stdio.h>
 // #include <Adafruit_USBD_Device.h>
+#include "HardwareRNG.h"
 #include "NodeDB.h"
 #include "PowerMon.h"
 #include "error.h"
@@ -398,15 +399,14 @@ void nrf52Setup()
 #endif
 
     // Init random seed
-    union seedParts {
-        uint32_t seed32;
-        uint8_t seed8[4];
-    } seed;
-    nRFCrypto.begin();
-    nRFCrypto.Random.generate(seed.seed8, sizeof(seed.seed8));
-    LOG_DEBUG("Set random seed %u", seed.seed32);
-    randomSeed(seed.seed32);
-    nRFCrypto.end();
+    uint32_t seed = 0;
+    if (!HardwareRNG::seed(seed)) {
+        LOG_WARN("Hardware RNG seed unavailable, using PRNG fallback");
+        // Use a hardware timer value as a fallback seed for better entropy
+        seed = micros();
+    }
+    LOG_DEBUG("Set random seed %u", seed);
+    randomSeed(seed);
 
     // Set up nrfx watchdog. Do not enable the watchdog yet (we do that
     // the first time through the main loop), so that other threads can

src/platform/portduino/PortduinoGlue.cpp

@@ -1,4 +1,5 @@
 #include "CryptoEngine.h"
+#include "HardwareRNG.h"
 #include "PortduinoGPIO.h"
 #include "SPIChip.h"
 #include "mesh/RF95Interface.h"
@@ -233,7 +234,9 @@ void portduinoSetup()
         std::cout << "Running in simulated mode." << std::endl;
         portduino_config.MaxNodes = 200; // Default to 200 nodes
         // Set the random seed equal to TCPPort to have a different seed per instance
-        randomSeed(TCPPort);
+        uint32_t seed = TCPPort;
+        HardwareRNG::seed(seed);
+        randomSeed(seed);
         return;
     }
 
@@ -512,7 +515,9 @@ void portduinoSetup()
 #endif
     printf("MAC ADDRESS: %02X:%02X:%02X:%02X:%02X:%02X\n", dmac[0], dmac[1], dmac[2], dmac[3], dmac[4], dmac[5]);
     // Rather important to set this, if not running simulated.
-    randomSeed(time(NULL));
+    uint32_t seed = static_cast<uint32_t>(time(NULL));
+    HardwareRNG::seed(seed);
+    randomSeed(seed);
 
     std::string defaultGpioChipName = gpioChipName + std::to_string(portduino_config.lora_default_gpiochip);
 

src/platform/rp2xx0/main-rp2xx0.cpp

@@ -1,3 +1,4 @@
+#include "HardwareRNG.h"
 #include "configuration.h"
 #include "hardware/xosc.h"
 #include <hardware/clocks.h>
@@ -98,10 +99,12 @@ void getMacAddr(uint8_t *dmac)
 
 void rp2040Setup()
 {
-    /* Sets a random seed to make sure we get different random numbers on each boot.
-       Taken from CPU cycle counter and ROSC oscillator, so should be pretty random.
-    */
-    randomSeed(rp2040.hwrand32());
+    /* Sets a random seed to make sure we get different random numbers on each boot. */
+    uint32_t seed = 0;
+    if (!HardwareRNG::seed(seed)) {
+        seed = rp2040.hwrand32();
+    }
+    randomSeed(seed);
 
 #ifdef RP2040_SLOW_CLOCK
     uint f_pll_sys = frequency_count_khz(CLOCKS_FC0_SRC_VALUE_PLL_SYS_CLKSRC_PRIMARY);