diff --git a/core/embed/sec/secret/unix/secret.c b/core/embed/sec/secret/unix/secret.c
index 64ee3e13d1..970f951acc 100644
--- a/core/embed/sec/secret/unix/secret.c
+++ b/core/embed/sec/secret/unix/secret.c
@@ -1,15 +1,137 @@
+#include <trezor_model.h>
+#include <trezor_rtl.h>
+
 #include <sec/secret.h>
+#include <sys/mpu.h>
+#include <util/flash.h>
 
 #ifdef KERNEL_MODE
 
-void secret_write_header(void) {}
+static secbool bootloader_locked_set = secfalse;
+static secbool bootloader_locked = secfalse;
 
-secbool secret_optiga_present(void) { return secfalse; }
+secbool secret_verify_header(void) {
+  uint8_t* addr = (uint8_t*)flash_area_get_address(&SECRET_AREA, 0,
+                                                   sizeof(SECRET_HEADER_MAGIC));
 
-void secret_optiga_erase(void) {}
+  if (addr == NULL) {
+    return secfalse;
+  }
 
-secbool secret_bootloader_locked(void) { return sectrue; }
+  mpu_mode_t mpu_mode = mpu_reconfig(MPU_MODE_SECRET);
 
-void secret_prepare_fw(secbool allow_run_with_secret, secbool _trust_all) {}
+  bootloader_locked =
+      memcmp(addr, SECRET_HEADER_MAGIC, sizeof(SECRET_HEADER_MAGIC)) == 0
+          ? sectrue
+          : secfalse;
+
+  mpu_restore(mpu_mode);
+
+  bootloader_locked_set = sectrue;
+  return bootloader_locked;
+}
+
+secbool secret_bootloader_locked(void) {
+  if (bootloader_locked_set != sectrue) {
+    // Set bootloader_locked.
+    secret_verify_header();
+  }
+
+  return bootloader_locked;
+}
+
+void secret_write_header(void) {
+  uint8_t header[SECRET_HEADER_LEN] = {0};
+  memcpy(header, SECRET_HEADER_MAGIC, 4);
+  secret_write(header, 0, SECRET_HEADER_LEN);
+}
+
+void secret_write(const uint8_t* data, uint32_t offset, uint32_t len) {
+  mpu_mode_t mpu_mode = mpu_reconfig(MPU_MODE_SECRET);
+  ensure(flash_unlock_write(), "secret write");
+  for (int i = 0; i < len; i++) {
+    ensure(flash_area_write_byte(&SECRET_AREA, offset + i, data[i]),
+           "secret write");
+  }
+  ensure(flash_lock_write(), "secret write");
+  mpu_restore(mpu_mode);
+}
+
+secbool secret_read(uint8_t* data, uint32_t offset, uint32_t len) {
+  if (sectrue != secret_verify_header()) {
+    return secfalse;
+  }
+
+  uint8_t* addr = (uint8_t*)flash_area_get_address(&SECRET_AREA, offset, len);
+
+  if (addr == NULL) {
+    return secfalse;
+  }
+
+  mpu_mode_t mpu_mode = mpu_reconfig(MPU_MODE_SECRET);
+  memcpy(data, addr, len);
+  mpu_restore(mpu_mode);
+
+  return sectrue;
+}
+
+secbool secret_wiped(void) {
+  uint32_t size = flash_area_get_size(&SECRET_AREA);
+  secbool wiped = sectrue;
+
+  mpu_mode_t mpu_mode = mpu_reconfig(MPU_MODE_SECRET);
+
+  for (int i = 0; i < size; i += 4) {
+    uint32_t* addr = (uint32_t*)flash_area_get_address(&SECRET_AREA, i, 4);
+    if (addr == NULL) {
+      wiped = secfalse;
+      break;
+    }
+    if (*addr != 0xFFFFFFFF) {
+      wiped = secfalse;
+      break;
+    }
+  }
+
+  mpu_restore(mpu_mode);
+
+  return wiped;
+}
+
+void secret_erase(void) {
+  mpu_mode_t mpu_mode = mpu_reconfig(MPU_MODE_SECRET);
+  ensure(flash_area_erase(&SECRET_AREA, NULL), "secret erase");
+  mpu_restore(mpu_mode);
+}
+
+secbool secret_optiga_set(const uint8_t secret[SECRET_OPTIGA_KEY_LEN]) {
+  secret_erase();
+  secret_write_header();
+  secret_write(secret, SECRET_OPTIGA_KEY_OFFSET, SECRET_OPTIGA_KEY_LEN);
+  return sectrue;
+}
+
+secbool secret_optiga_get(uint8_t dest[SECRET_OPTIGA_KEY_LEN]) {
+  return secret_read(dest, SECRET_OPTIGA_KEY_OFFSET, SECRET_OPTIGA_KEY_LEN);
+}
+
+secbool secret_optiga_present(void) {
+  return (sectrue != secret_wiped()) * sectrue;
+}
+
+secbool secret_optiga_writable(void) { return secret_wiped(); }
+
+void secret_optiga_erase(void) { secret_erase(); }
+
+void secret_prepare_fw(secbool allow_run_with_secret, secbool _trust_all) {
+#ifdef USE_OPTIGA
+  if (sectrue != allow_run_with_secret && sectrue != secret_wiped()) {
+    // This function does not return
+    show_install_restricted_screen();
+  }
+#endif
+}
+
+void secret_init(void) {}
 
 #endif  // KERNEL_MODE