diff --git a/cube/User/Inc/sinkStruct.h b/cube/User/Inc/sinkStruct.h
index 85153d7..881ba6f 100644
--- a/cube/User/Inc/sinkStruct.h
+++ b/cube/User/Inc/sinkStruct.h
@@ -19,4 +19,9 @@ typedef struct __attribute__((__packed__)) {
     t_event events[SECONDS_PER_MINUTE];
 } t_minuteStruct;
 
+typedef union {
+    t_minuteStruct s;
+    uint8_t b[sizeof(t_minuteStruct)];
+} t_minuteBuffer;
+
 #endif // _SINKSTRUCT_H_
\ No newline at end of file
diff --git a/cube/User/Src/counter.c b/cube/User/Src/counter.c
index 4199dd6..66ba3b5 100644
--- a/cube/User/Src/counter.c
+++ b/cube/User/Src/counter.c
@@ -27,10 +27,6 @@ volatile static uint32_t mainsCntCnt = 0;
 static t_seconds *seconds;
 
 
-typedef union {
-    t_minuteStruct s;
-    uint8_t b[sizeof(t_minuteStruct)];
-} t_minuteBuffer;
 
 #define NUM_OF_MINUTE_BUFFERS 2
 t_minuteBuffer minuteBuffers[NUM_OF_MINUTE_BUFFERS];
diff --git a/sink/sink20169.c b/sink/sink20169.c
index df20bd4..2af320e 100644
--- a/sink/sink20169.c
+++ b/sink/sink20169.c
@@ -4,6 +4,20 @@
 #include <netinet/in.h>
 #include <string.h>
 
+#include <sinkStruct.h>
+
+
+typedef struct {
+    char deviceId[sizeof(((t_configBlock*)0)->deviceId)];
+    char sharedSecret[sizeof(((t_configBlock*)0)->sharedSecret)];
+} t_device;
+
+const t_device devices[] = {
+    { .deviceId = "MainsCnt01", .sharedSecret = "sharedSecretGanzGeheim" },
+    { .deviceId = NULL, .sharedSecret = NULL }
+};
+
+
 
 int main() {
     int sockfd;
@@ -19,13 +33,52 @@ int main() {
 
     bind(sockfd, (const struct sockaddr *) &servaddr, sizeof(servaddr));
 
-    uint8_t buf[800];
+    t_minuteBuffer buf;
 
     while (1) {
-        int n = recvfrom(sockfd, buf, sizeof(buf), MSG_TRUNC,
+        int n = recvfrom(sockfd, buf.b, sizeof(buf.b), MSG_TRUNC,
                          (struct sockaddr *) &cliaddr, &cliaddrlen);
         printf("received %d octets from %04x\n", 
                n, cliaddr.sin_addr.s_addr);
+
+        if (n != sizeof(buf.b)) {
+            printf("Illegal packet size: %d\n", n);
+            continue;
+        }
+
+        uint8_t i = 0;
+        while (1) {
+            if (strncmp(devices[i].deviceId, buf.s.deviceId, sizeof(((t_configBlock*)0)->deviceId)) == 0) {
+                printf("Device found: %s\n", devices[i].deviceId);
+
+                uint8_t receivedHash[SHA256_BLOCK_SIZE];
+                memcpy(receivedHash, buf.s.hash, SHA256_BLOCK_SIZE);
+                memcpy(buf.s.hash, devices[i].sharedSecret, SHA256_BLOCK_SIZE);
+
+                SHA256_CTX ctx;
+                uint8_t calculatedHash[SHA256_BLOCK_SIZE];
+                sha256_init(&ctx);
+                sha256_update(&ctx, buf.b, sizeof(buf.b));
+                sha256_final(&ctx, calculatedHash);
+
+                if (memcmp(receivedHash, calculatedHash, SHA256_BLOCK_SIZE) != 0) {
+                    printf("Invalid hash\n");
+                }
+
+                printf("DeviceId: %s\n", buf.s.deviceId);
+                printf("Location: %s\n", buf.s.location);
+                for (uint8_t j = 0; j < SECONDS_PER_MINUTE; j++) {
+                    printf("Time: %llu, Frequency: %lu\n", buf.s.events[j].timestamp, buf.s.events[j].frequency);
+                }
+                printf("\n");
+
+
+                break;
+            } else {
+                printf("Unknown device\n");
+            }
+        }
+
     }
 
 }