Добавил свое решение для сервера

tasks/reverse/server/khabalov.c

@@ -0,0 +1,51 @@
+#include <time.h>
+#include <stdio.h>
+#include <stdlib.h>
+#define _GNU_SOURCE
+#include <string.h>
+
+
+unsigned int MakeChecksum(unsigned char *buffer, int len)
+{
+  unsigned int result;
+
+  result = 0;
+  for (int i = 0; i < len; i = i + 1) {
+    result = (result << 3 | result >> 0x1d) ^ buffer[i];
+  }
+
+  return result;
+}
+
+
+unsigned char *make_message(const unsigned char* s) {
+    int len = strlen(s);
+    unsigned char* message = (char*) calloc(1, len + 11);
+
+    message[8] = len + 7;
+    message[10] = len;
+
+    message[9] = 0x2A;
+
+    memcpy(message + 11, s, len);
+
+    *((unsigned int*)message + 1) = time(0LL);
+    
+    *(unsigned int*) message = MakeChecksum(message + 4, len + 7);
+
+    return message;
+}
+
+int main() {
+    unsigned char message[] = "g1mm3_th3_k3y";
+
+    size_t len = strlen(message);
+
+    for (int i = 0; i < len; i++) {
+        message[i] ^= 42;
+    }
+
+    fwrite(make_message(message), 1, strlen(message) + 11, stdout);
+
+    return 0;
+}