memory hygiene code

src/util/hygiene.c

@@ -0,0 +1,31 @@
+#include "hygiene.h"
+
+#include <stdint.h>
+#include <string.h>
+
+static void* (*volatile volatileMemset)(void*, int, size_t) = memset;
+
+void bravais_hygiene_zero(void* ptr, size_t len) {
+    if (!ptr || len <= 0) {
+        return;
+    }
+
+    volatileMemset(ptr, 0, len);
+}
+
+bool bravais_ct_equal(const void* a, const void* b, size_t len) {
+    if (!a || !b || len <= 0) {
+        return false;
+    }
+
+    const volatile uint8_t* left = a;
+    const volatile uint8_t* right = b;
+
+    uint8_t diff = 0;
+
+    for (size_t i = 0; i < len; i++) {
+        diff |= (uint8_t)(left[i] ^ right[i]);
+    }
+
+    return diff == 0;
+}

src/util/hygiene.h

@@ -0,0 +1,15 @@
+// hygiene.h
+// Memory hygiene utils - primarily for keys
+
+#ifndef BRAVAIS_HYGIENE_H
+#define BRAVAIS_HYGIENE_H
+
+#include <stddef.h>
+
+// Zero out a memory region
+void bravais_hygiene_zero(void* ptr, size_t len);
+
+// Constant-time equality check
+bool bravais_ct_equal(const void* a, const void* b, size_t len);
+
+#endif // BRAVAIS_HYGIENE_H