altos: Use standard FIPS testing for chaoskey

[fw/altos] / src / drivers / ao_trng_send.c

diff --git a/src/drivers/ao_trng_send.c b/src/drivers/ao_trng_send.c
index 171a345fbe2db047feebaab19c25a55ba03410e9..85034efd767f7337ebbabbff75a428fccd6b8e73 100644 (file)
--- a/src/drivers/ao_trng_send.c
+++ b/src/drivers/ao_trng_send.c
@@ -3,7 +3,8 @@
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; version 2 of the License.
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful, but
  * WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -22,7 +23,7 @@
 #include <ao_exti.h>
 #include <ao_power.h>
 
-static struct ao_task  ao_trng_send_task, ao_trng_send_raw_task;
+static struct ao_task  ao_trng_send_task;
 static uint8_t         trng_running;
 static AO_TICK_TYPE    trng_power_time;
 
@@ -30,6 +31,10 @@ static AO_TICK_TYPE  trng_power_time;
 
 static uint8_t         random_mutex;
 
+#if AO_USB_HAS_IN2
+
+static struct ao_task  ao_trng_send_raw_task;
+
 static void
 ao_trng_get_raw(uint16_t *buf)
 {
@@ -90,18 +95,9 @@ ao_trng_send_raw(void)
        }
 }
 
-/* Make sure there's at least 8 bits of variance in the samples */
-#define MIN_VARIANCE           (128 * 128)
-
-/* Make sure the signal is spread around a bit */
-#define MAX_VARIANCE           (512 * 512)
-
-#define ADD_STATS(value) do {                  \
-               sum += (value);                 \
-               sum2 += (value) * (value);      \
-       } while(0)
+#endif
 
-#define VARIANCE(n)    ((sum2 - (sum / (n) * sum)) / (n))
+static uint32_t        previous[AO_USB_IN_SIZE / sizeof (uint16_t)];
 
 static int
 ao_trng_get_cooked(uint16_t *buf)
@@ -109,29 +105,24 @@ ao_trng_get_cooked(uint16_t *buf)
        uint16_t        i;
        uint16_t        t;
        uint32_t        *rnd = (uint32_t *) ao_adc_ring;
-       int32_t         sum, sum2, var;
+       uint8_t         mismatch = 0;
 
-       sum = sum2 = 0;
        t = ao_adc_get(AO_USB_IN_SIZE) >> 1;            /* one 16-bit value per output byte */
        for (i = 0; i < AO_USB_IN_SIZE / sizeof (uint16_t); i++) {
                uint32_t        v;
-               uint16_t        v1, v2;
 
                /* Fetch two values in one operation */
                v = rnd[t];
+               if (v != previous[i]) {
+                       mismatch = 1;
+                       previous[i] = v;
+               }
                t = (t + 1) & ((AO_ADC_RING_SIZE >> 1) - 1);
 
                *buf++ = ao_crc_in_32_out_16(v);
-
-               v1 = v;
-               v2 = v >> 16;
-
-               ADD_STATS(v1);
-               ADD_STATS(v2);
        }
        ao_adc_ack(AO_USB_IN_SIZE);
-       var = VARIANCE(2 * AO_USB_IN_SIZE / sizeof (uint16_t));
-       return var >= MIN_VARIANCE && var <= MAX_VARIANCE;
+       return mismatch;
 }
 
 #define AO_TRNG_START_WAIT     1024
@@ -181,7 +172,9 @@ ao_trng_send(void)
        if (failed > AO_TRNG_START_CHECK / 4)
                ao_panic(AO_PANIC_DMA);
 
+#if AO_USB_HAS_IN2
        ao_add_task(&ao_trng_send_raw_task, ao_trng_send_raw, "trng_send_raw");
+#endif
 
 #ifdef AO_USB_START_DISABLED
        ao_usb_enable();