Overview On Advanced Encryption Standard (AES)
By: Muhammad Maaz Irfan
Tags: Encryption, Cryptography, Deep Learning

Keywords: Advanced Encryption Standard (AES); cryptography; cryptanalysis; Cryptographic algorithms; encryption; Privacy-preserving; Security

Introduction:

In the last era when the internet is getting popular and users increased day by day. Security and privacy concerns are growing, because of the accessibility of big data; the collection of heterogeneous data is more convenient nowadays. Vulnerability raises major concerns in security-sensitive environments. Leakage of private data is caused by network attacks or eavesdropping tricks yet these opportunities come with some challenges related to data security and privacy. Cryptography is an essential component for secure communication and transmission of information through secure services. However, it has serious threats in many applications, recent algorithms such as DES known as Data Encryption Standard only has the 56-bit key which is small and cannot use in today’s applications [1]. Since triple-DES can solve the length of keys. But the DES is mainly designed for hardware encryptions, now a day’s majority of applications that used in software which comparatively inefficient. To overcome such issues there are few security cryptosystems in 1997, the National Institute of Standard and Technology known as NIST introduced a new algorithm named Advanced Encryption Standard (AES) which is the replacement of previously used cryptosystems DES. AES algorithm provides good security in both application hardware and also in software, it may require a trade-off between different speed/ area. And used various applications such as mobile phones, RFID cards (smart cards), etc. other applications, such as WWW servers and ATMs. Digital video recording which requires speed area ratio. In AES architectural optimizations make use of duplicating the round units, while algorithmic optimizations explore simplification inside each encryption/decryption round unit. In this article, we will focus on the AES method which gives secure computation and usage in different applications. The working of the AES algorithm, Also how researchers modified the current technique and give the overview. And in the end, we will conclude our article in the last section.

Advanced Encryption Standard algorithm describes as AES which is a symmetric-key block cipher (same key used for both encryption and decryption) for the user’s data. It is available in various different sets. AES is the first and only cipher approved accessible by National Security Agency (NSA) [2]. AES algorithm designed on principal to work on both software and hardware also on cutting-edge IoT, unlike previously based cryptosystem such as DES, AES block size is 128 bits and a key size of 128,192 or 256 bits [3]. Their algorithm performs on two-dimensional array bytes called the state and each byte consist of 8 bits. They have four rows of bytes and each row contains Nb bytes. Nb = 128 / (4 x 8) = 4 bytes. In each column of four bytes array form a 32-bit word, the row number is taking as an index for the four bytes in each

[3] Figure 1: An array of input bytes

word. In the first phase, for the input bytes of the array, it is mapped on state array as followed on fig 1, taking 128- bits can have expressed as 16 bytes, the encryption, and decryption performed on the state, in the end, the final value is mapped to the output bytes. The main part of AES algorithm is the key which mapped on 4 rows of bytes in a similar way, apart from the number of bytes in each row which is denoted as Nk it can be 4, 6, or 8 it depends on the length of the key, K is 128, 192, or 25 bits correspondingly. It is an iterative algorithm, total number of rounds Nr is 10 when

Nk = 4 , Nk =12 when Nk = 6 and Nr = 14 when Nk =8. At the beginning of the encryption, it will take input and copied to the state array. In the initial round key, take as the addition, Nr rounds of encryption are performed. The first Nr — 1 rounds are the same, with a small difference in the final round. As mentioned in fig 2 each Nr — 1 round contains 4 transformations are followed: Sub bytes, Shift Rows, Add Round Key and Mix

[3] Figure 2: Encryption Structure of the AES algorithm.

Columns comes in final round. In every step, each round consists of four layers. In the first layer, the S-box of order 8 is applied to each byte. For linear mixing, the second and third layer is used. In these layers, the column are mixed and rows of the array are shifted, the subkey bytes are XOR with each byte of the array in the fourth layer. On the key size round operation done iteratively. In decryption, a similar process will take place with the same sequence as in encryption but it will be in reverse order [4].

AES has some characteristics which are the following:

1. It gives compactness of code with good efficiency on a large range of platforms.

2. AES having a simple design.

3. It gives secure computation and gives protection with every single attack.

4. Cryptography is an essential

5. component for secure communication and transmission of

6. information through security services like confidentiality, data

7. integrity, access control, authentication, and non-repudiation.

Conclusion

In this report, we focused on a cryptosystem based algorithm known as Advance encryption system, whereas we discussed the security issues and cryptosystem and also use in other applications, its an innovative method for helping two unknown parties to communicate securely. We also focus on the working of AES. This method is authentic and not considered as vulnerable to attacks. In the last paragraph, we tried to discuss briefly the mechanism with the given example.

Reference:

[1] RSA Data Security Inc., www.rsa.com

[2] Burns, Thomas L. (1990). “The Origins of the National Security Agency”

[3] Zhang, Xinmiao, and Keshab K. Parhi. “Implementation approaches for the advanced encryption standard algorithm.” IEEE Circuits and Systems Magazine 2.4 (2002): 24–46.

[4]Mushtaq, Muhammad Faheem, et al. “A survey on the cryptographic encryption algorithms.” International Journal of Advanced Computer Science and Applications 8.11 (2017): 333–344.

[5] https://mortendahl.github.io/2017/09/03/the-spdz-protocol-part1/