מה הסיבוכיות ריצה וזיכרון של התקפת search exhaustive על מערכת קריפטוגרפית 4-DES (מערכת שמפעילה ארבע פעמים את אלגוריתם DES)?

Explanation: DES (Data Encryption Standard) uses a 56-bit key, so the complexity of a brute-force attack (exhaustive search) on single DES is 2^56 DES means running DES four times, which increases the complexity because it increases the key size to 4 *56 = 224 bits Therefore, the running complexity of an exhaustive search on a 4-DES system is O(2^224), s you need to search through all possible combinations of a 224-bit key. (The memory complexity is O(2^1 because the memory required for a brute-force attack doesn’t scale with the key size—it generally only requires storing a few intermediate values at any given time. A brute-force attack is not memory-intensive, unlike attacks such as meet-in-the-middle that require more memory.