add encrypting for save files

add libhydrogen for encrypting and decrypting #9
2026-04-03 14:59:37 +02:00
parent abb6556fd4
commit c277ab10d9
68 changed files with 5737 additions and 74 deletions
@@ -0,0 +1,63 @@
+#include <Arduino.h>
+
+static bool
+hydro_random_rbit(uint16_t x)
+{
+    uint8_t x8;
+
+    x8 = ((uint8_t) (x >> 8)) ^ (uint8_t) x;
+    x8 = (x8 >> 4) ^ (x8 & 0xf);
+    x8 = (x8 >> 2) ^ (x8 & 0x3);
+    x8 = (x8 >> 1) ^ x8;
+
+    return (bool) (x8 & 1);
+}
+
+static int
+hydro_random_init(void)
+{
+    const char       ctx[hydro_hash_CONTEXTBYTES] = { 'h', 'y', 'd', 'r', 'o', 'P', 'R', 'G' };
+    hydro_hash_state st;
+    uint16_t         ebits = 0;
+    uint16_t         tc;
+    bool             a, b;
+
+    cli();
+    MCUSR = 0;
+    WDTCSR |= _BV(WDCE) | _BV(WDE);
+    WDTCSR = _BV(WDIE);
+    sei();
+
+    hydro_hash_init(&st, ctx, NULL);
+
+    while (ebits < 256) {
+        delay(1);
+        tc = TCNT1;
+        hydro_hash_update(&st, (const uint8_t *) &tc, sizeof tc);
+        a = hydro_random_rbit(tc);
+        delay(1);
+        tc = TCNT1;
+        b  = hydro_random_rbit(tc);
+        hydro_hash_update(&st, (const uint8_t *) &tc, sizeof tc);
+        if (a == b) {
+            continue;
+        }
+        hydro_hash_update(&st, (const uint8_t *) &b, sizeof b);
+        ebits++;
+    }
+
+    cli();
+    MCUSR = 0;
+    WDTCSR |= _BV(WDCE) | _BV(WDE);
+    WDTCSR = 0;
+    sei();
+
+    hydro_hash_final(&st, hydro_random_context.state, sizeof hydro_random_context.state);
+    hydro_random_context.counter = ~LOAD64_LE(hydro_random_context.state);
+
+    return 0;
+}
+
+ISR(WDT_vect)
+{
+}