diff --git a/src/lora/encryption.c b/src/lora/encryption.c
new file mode 100644
index 0000000..b723cc2
--- /dev/null
+++ b/src/lora/encryption.c
@@ -0,0 +1,29 @@
+#include <zephyr/device.h>
+#include <errno.h>
+#include <zephyr/sys/util.h>
+#include <zephyr/kernel.h>
+#include <stdint.h>
+
+const uint8_t XOR_KEY = 0x5A; // Einfacher, geheimer Schlüssel
+
+void xorCrypt(const char *input, char *output, uint8_t key) {
+   size_t len = strlen(input);
+   for (size_t i = 0; i < len; i++) {
+       output[i] = input[i] ^ key;
+   }
+   output[len] = '\0'; // Null-Terminierung für gültige C-Strings
+}
+ 
+uint16_t computeCRC16(const char *data) {
+    uint16_t crc = 0xFFFF;
+    for (size_t i = 0; i < strlen(data); i++) {
+        crc ^= (uint8_t)data[i] << 8;
+        for (int j = 0; j < 8; j++) {
+            if (crc & 0x8000)
+                crc = (crc << 1) ^ 0x1021;
+            else
+                crc <<= 1;
+        }
+    }
+    return crc;
+}
\ No newline at end of file
diff --git a/src/lora/synch.c b/src/lora/synch.c
new file mode 100644
index 0000000..e024e2d
--- /dev/null
+++ b/src/lora/synch.c
@@ -0,0 +1,158 @@
+#include <zephyr/kernel.h>
+#include <zephyr/device.h>
+#include <zephyr/sys/printk.h>
+#include <zephyr/sys/byteorder.h>
+#include <zephyr/drivers/lora.h>
+#include <zephyr/drivers/gpio.h>
+#include <stdlib.h>
+
+#define DEFAULT_RADIO_NODE DT_ALIAS(lora0)
+#define LED0_NODE DT_ALIAS(led0)
+#define SW0_NODE  DT_ALIAS(sw0)
+#define MAX_SAMPLES 10
+
+// 🔧 Vorwärtsdeklarationen
+void synchronite(struct k_work *work);
+K_WORK_DEFINE(sync_work, synchronite);
+
+// 📟 Hardware
+static const struct gpio_dt_spec led_green = GPIO_DT_SPEC_GET(LED0_NODE, gpios);
+static const struct gpio_dt_spec button = GPIO_DT_SPEC_GET_OR(SW0_NODE, gpios, {0});
+static struct gpio_callback button_cb_data;
+
+// 📊 Sync-Variablen
+uint32_t offsets[MAX_SAMPLES];
+uint8_t offset_count = 0;
+uint32_t sync_offset = 0;
+uint32_t sync_offset_s = 0;
+bool synchronized = false;
+
+uint32_t samples[MAX_SAMPLES];
+
+const struct device *lora_dev = DEVICE_DT_GET(DEFAULT_RADIO_NODE);
+
+struct lora_modem_config config = {
+    .frequency = 868100000,
+    .bandwidth = BW_125_KHZ,
+    .datarate = SF_7,
+    .preamble_len = 8,
+    .coding_rate = CR_4_5,
+    .tx_power = 14,
+    .tx = false,
+};
+
+BUILD_ASSERT(DT_NODE_HAS_STATUS_OKAY(DEFAULT_RADIO_NODE),
+             "No default LoRa radio specified in DT");
+
+// 📡 Callback
+void lora_receive_cb(const struct device *dev, uint8_t *data, uint16_t size,
+                     int16_t rssi, int8_t snr, void *user_data)
+{
+    if ((size >= 4) && (!synchronized)) {
+        uint32_t master_timer_value = sys_get_le32(data);  //uint8_t master_timer_value = data[0] % 60;
+        uint32_t local_now = k_uptime_get();
+
+        printk("📡 Empfangen: %u ms\n", master_timer_value);
+        gpio_pin_toggle_dt(&led_green);
+
+        if (offset_count < MAX_SAMPLES) {
+            samples[offset_count] = local_now + master_timer_value;
+            offset_count++;
+        }
+
+        if (offset_count >= MAX_SAMPLES) {
+            uint32_t offsets = 0;
+
+            printk("Intervall: %d: %d: %d\n",(MAX_SAMPLES/5), (MAX_SAMPLES*4/5), (MAX_SAMPLES * 3/5));
+            for (int i = (MAX_SAMPLES/5); i < (MAX_SAMPLES*4/5); i++) {
+                offsets += samples[i];
+            }
+            
+            sync_offset_s = offsets /( MAX_SAMPLES * 3/5);
+
+            sync_offset_s -= local_now;
+                        
+            synchronized = true;
+
+            int ret = lora_recv_async(lora_dev, NULL, NULL);
+
+            if (ret != 0){
+                printk("Problem beim deaktivieren der Synchronsation: %d\n", ret);
+            }
+
+            printk("✅ Synchronisiert! Offset: %u Sekunden\n", sync_offset_s);
+            gpio_pin_set_dt(&led_green, 1);
+            return;
+        }
+    }
+}
+
+// 🕒 Hilfsfunktion: synchronisierter Timerwert
+uint32_t get_synced_timer() {
+    if (!synchronized) return 0;
+    uint32_t now = k_uptime_get();
+    return (sync_offset > now) ? (sync_offset - now) : 0;
+}
+
+// 🔘 Button Interrupt
+void button_pressed(const struct device *dev, struct gpio_callback *cb,
+                    uint32_t pins)
+{
+    printk("🔘 Button gedrückt\n");
+    k_work_submit(&sync_work);  // startet synchronite()
+}
+
+
+// ⚙️ GPIO Initialisierung
+int init_led_and_button(void) {
+    int ret;
+
+    if (!gpio_is_ready_dt(&led_green)) return -1;
+    ret = gpio_pin_configure_dt(&led_green, GPIO_OUTPUT_INACTIVE);
+    if (ret < 0) return ret;
+
+    if (!gpio_is_ready_dt(&button)) return -1;
+    ret = gpio_pin_configure_dt(&button, GPIO_INPUT);
+    if (ret < 0) return ret;
+
+    ret = gpio_pin_interrupt_configure_dt(&button, GPIO_INT_EDGE_TO_ACTIVE);
+    if (ret < 0) return ret;
+
+    gpio_init_callback(&button_cb_data, button_pressed, BIT(button.pin));
+    gpio_add_callback(button.port, &button_cb_data);
+
+    return 0;
+}
+
+void synchronite(struct k_work *work){
+    offset_count = 0;
+    synchronized = false;
+    memset(offsets, 0, sizeof(offsets));
+    printk("Initilisierung abgeschlossen");
+    
+    int ret = lora_config(lora_dev, &config);
+
+    ret = lora_recv_async(lora_dev, lora_receive_cb, NULL);
+    printk("Empfang gestartet (ret = %d)\n", ret);
+}
+
+// 🚀 Main
+int init(void) {
+    printk("🔋 Starte LoRa-Empfänger\n");
+
+    if (init_led_and_button() != 0) {
+        printk("❌ GPIO-Initialisierung fehlgeschlagen\n");
+        return -1;
+    }
+
+    if (!device_is_ready(lora_dev)) {
+        printk("❌ LoRa nicht bereit\n");
+        return -1;
+    }
+
+	gpio_pin_set_dt(&led_green, 0);
+
+    while (1) {
+        k_msleep(1000);
+    }
+}
\ No newline at end of file