Final answer:
The real world key length for DES is only 56-bits because of the limitations of the algorithm's design and the computing capabilities at the time. However, 56-bits is no longer considered secure enough.
Step-by-step explanation:
The real world key length for DES (Data Encryption Standard) is only 56-bits because of the limitations of the algorithm's design. DES was developed in the 1970s, when computers were not as powerful as they are today. At the time, a 56-bit key was considered to be secure enough for most applications.
The key length was intentionally kept at 56-bits to ensure compatibility with the hardware available at that time. With a 56-bit key, there are a total of 2^56 possible combinations, which was believed to be sufficient to protect against brute-force attacks.
However, as computing power has increased over the years, 56-bits is no longer considered secure enough. Today, it is recommended to use more secure encryption algorithms, such as AES (Advanced Encryption Standard), which supports key lengths of 128, 192, and 256 bits.