Advanced Encryption Standard(AES)

3 min readOct 15, 2020


Overview of AES

If you are a part of a company that uses cyber security solutions, you surely know about the Advanced Encryption Standard before. In this blog, we will take a closer look at AES and its importance which results in its use in companies all over the world.

Advanced Encryption Standard(AES) was made official in 2001 and was considered as a successor to Data Encryption Standard (DES) by the National Institute of Standards and Technology (NIST).

The developers of AES are Joan Deamen and Vincent Rijmen. They proposed their block cipher to the National Institute of Standards and Technology during the selection process of an AES. To attain a secure AES, NIST considered three different block ciphers from the Rijndael family of ciphers.

After proper research, the block cipher developed by Rijmen and Daemen was selected. The AES was first used in the United States but after a while, it became popular all over the world.

Advanced Encryption Standard is characterized as being a symmetric block cipher, in other words it uses the same key for encryption and decryption.

Working of AES

AES uses substitutions and permutations in its operation. AES uses bytes in its operation instead of bits. 128 bits are converted into 16 bytes and these 16 bytes are placed in the form of a matrix(4x4 matrix). Rounds in AES depends on the length of key which was not the case in DES. The rounds used by AES in 128 bit are 10, 12 for 192 bit and for 256 bit, 14 rounds are used.

Each round consists of 4 steps which are Sub Bytes, Shift Rows, Mix Columns and Add Round Key.

In Sub Bytes, all the values in the 4x4 matrix are substituted. Shift Rows involves the shifting of rows to left but in different ways. First row values are not shifted, second row is shifted by one, third row by two and lastly fourth row by 3 values to the left. Mix Columns takes one column from the matrix and performs a mathematical function on it. This function gives new outputs which replace the previous values of the column before the transformation. After all the 4 columns are transformed, a new matrix is obtained containing different values. The matrix of 16 bytes are now converted back to 128 bit and XOR function is used with the round key. After the operation there are two possibilities, if this is the last round, the obtained output is the cipher text else we start the next round by converting them again into 16 bytes.

Need for developing AES

The Data Encryption Standard (DES) was being used before AES but it was becoming increasingly vulnerable to brute force attacks. NIST realized that there was an imminent need for a better and more developed replacement of DES. Hence AES was introduced as a better, newer and more advanced encryption algorithm.

Nowadays, AES is used by various organizations for free in their various programs. But the assurance of AES can only be safeguarded by its correct use and perfect management.


AES algorithm is very fast and accurate, but its percentage of accuracy depends on how it’s utilized. Effective attacks are typically launched on the implementation and not on the algorithm itself unlike the brute force attacks. It can be equated to phishing attacks — versus attacking the technology behind the service that may be hard to breach.

It is true that I like going with a effective security option, a lot of AES encryption is occuring without us even knowing it. AES encryption is locking down spots of the internet that would otherwise be wide open. It is important to know how to identify the open holes and be able to know how to plug them.

So to conclude I would like to say that appreciate the encryption implementations we have, use the best ones when needed, and happy discovering new ones!