Cisco Certified Network Associate (CCNA) Practice Exam

What algorithm can use multiple 56-bit keys to enhance security and is still considered secure?

1. Data Encryption Standard (DES)

2. Advanced Encryption Standard (AES)

3. Triple DES (3DES)

4. Blowfish Algorithm

The correct answer is: Triple DES (3DES)

The algorithm that enhances security by utilizing multiple 56-bit keys is Triple DES (3DES). This algorithm improves upon the original Data Encryption Standard (DES) by applying the DES encryption process three times with either two or three different keys. The fundamental principle behind 3DES is its approach to encryption, which significantly increases the effective key strength compared to DES alone. While DES uses a single 56-bit key, 3DES can use either two separate 56-bit keys for a total effective key length of 112 bits or three keys for a total effective key length of 168 bits. This means that even if a brute-force attack is attempted against it, the number of possible keys is vastly increased, making it far more challenging to break. 3DES was designed to be backward compatible with DES and to strengthen security in environments where a migration to stronger algorithms could not be immediately accomplished. Although newer algorithms like AES offer better performance and security efficiencies, 3DES remains a viable option in scenarios where legacy systems still rely on DES. Other encryption options like AES and Blowfish have their strengths, but they do not specifically utilize the same methodology of employing multiple keys as part of their standard operations. AES has a different structure based on substitution-permutation rather