Published as a FIPS 197 standard in 2001, the AES (Advanced Encryption Standard) data encryption was meant to substitute the 1976 DES (Data Encryption Standard) has shown vulnerabilities and been considered antiquated. It should be noted that the AES is not a single institution’s product but rather a result of an open competition that attracted multiple research teams from around the world. Though both AES and DES are examples of symmetric block ciphers, AES is a more elegant and efficient cryptographic algorithm empowered by improved mathematical foundations. The main power of AES rests in a variety of key lengths (Aleisa, 2015). Generally, the longer a key is, the better the security that comes with it. Not only that but a variety in the key length allows for future-proofing the algorithm in case the performance of exhaustive key searches advances (Aleisa, 2015). Therefore, AES is superior to DES since the latter only supports the 56-bit key length while with the former, the key length can be 128-bits, 192-bits, and 256-bits.
When it comes to the structure, DES employs the Feistel network whose major disadvantage is the limited capacity for parallelization, which slows down the algorithm. Besides, Feistel ciphers only transform part of the internal state each round (Rihan, Khalid & Osman, 2015). In contrast, AES relies on permutation-substitution, which implies a series of substitution and permutation steps that create an encrypted block. The structure of AES makes it inherently less susceptible to cryptanalysis. What further adds to the strength of AES is the flexibility in the number of rounds (example: 10 rounds for 128 bit, 12 rounds for 192 bit, and 14 rounds for 256 bits).
Reference
Aleisa, N. (2015). A Comparison of the 3DES and AES Encryption Standards. International Journal of Security and Its Applications, 9(7), 241-246.
Rihan, S. D., Khalid, A., & Osman, S. E. F. (2015). A performance comparison of encryption algorithms AES and DES. International Journal of Engineering Research & Technology (IJERT), 4(12), 151-154.