Comparison of Meet-in-the-middle Attacks on 2-DES and 2-AES with Four Scenarios

The Data Encryption Standard (DES) is a symmetric key encryption algorithm developed in the early 1970s by IBM. The 2-DES algorithm is a DES algorithm that is encrypted two times. However, the 2-DES algorithm is theoretically vulnerable to meet-in-the-middle attacks. In this research, a Meet-in-the-middle attack is carried out on the 2-DES algorithm with the sample of 2
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and ensures the key used is in that range. Apart from 2-DES, an attack was also carried out on 2-AES as a comparison. The attack is conducted on both algorithms using four encryption modes: ECB, CBC, CFB, and OFB. The attacks were carried out in four scenarios that are encryption-encryption, encryption-decryption, decryption-encryption, and decryption-decryption. The attack results show that the MITM attack are successfully recovered the secret keys used on both algorithms for all modes and all scenarios. The consuming time of the attacks observed on both algorithms do not show that the scenario affects the consuming time on each algorithm. On the other hand, the encryption mode OFB and CFB need longer time than other modes on DES, but has no effect on AES for all scenarios.