Final answer:
The cryptographic key length used in DES is 56 bits, which is now considered less secure compared to modern encryption standards like AES.
Step-by-step explanation:
The length of the cryptographic key used in the Data Encryption Standard (DES) cryptosystem is 56 bits. DES uses a fixed-length key of 56 bits for encryption, which is considered relatively short by modern standards and has been superseded by more secure algorithms like AES (Advanced Encryption Standard). Despite the short key length, which was initially chosen to fit hardware constraints at the time of its development and also due to government restrictions on exportation of high-grade cryptographic technology, DES was a widely used symmetric-key encryption algorithm.