Whenever you send a message, pay online, or backup files to the cloud, encryption is operating behind the scenes to keep your information safe using AES cryptography. In the centre of this secure digital experience is the Advanced Encryption Standard (AES).<\/p>\n
AES was officially approved by NIST (National Institute of Standards and Technology) in 2001 to replace the ageing DES algorithm, a new standard for the entire world’s encryption. This article details the explanation of AES in a simple format suitable for interview preparation.
\nBefore learning about Advanced Encryption Standard (AES), its classification must be understood first symmetric encryption.<\/p>\n
Symmetric Encryption<\/strong> Asymmetric Encryption<\/strong> AES is an algorithm type of Block Cipher which encrypts the data in a fixed-size block (128 bits). Unlike stream ciphers that handle data bit by bit, block ciphers like AES process chunks of information, offering stronger and more structured security.<\/p>\n Advanced Encryption Standard (AES) is supported with three key lengths<\/p>\n Most generally, the longer the encryption key, the harder it is to crack. Take AES-128, for example, cracking it by brute force with today\u2019s computing power would take billions of years, making it practically unbreakable.<\/p>\n Although AES is very good in itself, the issue of how to handle encryption keys is something that remains a major challenge. Ensuring how keys are stored, shared and handled during their entire lifecycle forms a major factor in the security of any encrypted system.<\/p>\n AES uses a process called key expansion, or key scheduling, to generate a series of round keys from the original key. This makes sure that each round of encryption or decryption uses a different key derived from the main one.<\/p>\n Advanced Encryption Standard (AES Cryptography) encryption transforms plaintext into ciphertext through a series of mathematical operations known as rounds. The number of rounds in AES encryption changes based on the length of the key used in the process.<\/p>\n Each round of AES involves four main steps<\/p>\n This is a substitution step.<\/p>\n This is a permutation step.<\/p>\n Each row of the matrix is moved to the left.<\/p>\n Before<\/p>\n [ b0 | b1 | b2 | b3 ] After<\/p>\n [ b0 | b1 | b2 | b3 ] Another permutation step.<\/p>\n Example transformation<\/p>\n [ c0 ] [ 2 3 1 1 ] [ b0 ] (Note: This step is not performed in the final round.)<\/p>\n The AES process proceeds for all the rounds. The final round of AES skips the MixColumns step.<\/p>\n AES decryption works by reversing the steps of the encryption process. Each block (128 bits) passes through 10, 12, or 14 rounds depending on the key size.<\/p>\n Each round of decryption goes through these steps<\/p>\n XORs the state with the round key.<\/p>\n Matrix multiplication is performed using a constant matrix that differs from the one used in encryption.<\/p>\n Example<\/p>\n [ b0 ] [ 14 11 13 9 ] [ c0 ] The row shifts are reversed by moving them to the right.<\/p>\n The bytes are replaced using the inverse S-box, which undoes the SubBytes transformation.<\/p>\n These reversed steps collectively restore the original plaintext from the ciphertext.<\/p>\n AES generates a different round key for each stage using a key scheduling algorithm.<\/p>\n Start with the initial cipher key.<\/p>\n For each new round key<\/p>\n This ensures cryptographic uniqueness for every round.<\/p>\n Frequently Asked Questions in the interview<\/p>\n Conclusion<\/strong><\/p>\n AES is a basic element in current data protection. From its initial design of having symmetric constructs to its transformational processes, this building block has become a permanent structure in securing communication in different platforms and industries. Its popularity and strong architecture demonstrate its efficiency and resistance to modern risks.<\/p>\n Whether you are learning about cybersecurity, getting yourself ready for technical interviews or working with modern AES cryptography technologies, knowledge of AES is beneficial for the long term, professionally. It is not only with technical understanding but also with awareness regarding the importance of data protection in a growing digital environment \u2013 the more one knows about how AES works, the better.<\/p>\n","protected":false},"excerpt":{"rendered":" Whenever you send a message, pay online, or backup files to the cloud, encryption is operating behind the scenes to keep your information safe using AES cryptography. In the centre of this secure digital experience is the Advanced Encryption Standard (AES). AES was officially approved by NIST (National Institute of Standards and Technology) in 2001 […]<\/p>\n","protected":false},"author":52,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-19520","post","type-post","status-publish","format-standard","hentry","category-miscellaneous"],"yoast_head":"\n
\nSymmetric encryption depends on a single shared secret key for both encrypting and decrypting data. AES is one of the most commonly used examples of this method.<\/p>\n
\nIn Asymmetric encryption, there is a pair of keys, a public and a private, with one key encrypting the data, and another key decrypting the data. RSA is an example of this method.<\/p>\nBlock Cipher Basics<\/h2>\n
Key Size in AES<\/h2>\n
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Importance of Key Management<\/h3>\n
Creation of Round Keys<\/h2>\n
The AES Encryption: A Step-by-Step Guide<\/h2>\n
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High-Level Overview<\/h2>\n
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SubBytes<\/h3>\n
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ShiftRows<\/h3>\n
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\n[ b4 | b5 | b6 | b7 ]
\n[ b8 | b9 | b10 | b11 ]
\n[ b12 | b13 | b14 | b15 ]<\/p>\n
\n[ b5 | b6 | b7 | b4 ]
\n[ b10 | b11 | b8 | b9 ]
\n[ b15 | b12 | b13 | b14 ]<\/p>\nMix Columns<\/h3>\n
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\n[ c1 ] = [ 1 2 3 1 ] x [ b1 ]
\n[ c2 ] [ 1 1 2 3 ] [ b2 ]
\n[ c3 ] [ 3 1 1 2 ] [ b3 ]<\/p>\nAdd Round Key<\/h3>\n
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AES Decryption<\/h2>\n
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AddRoundKey<\/h3>\n
Inverse MixColumns<\/h3>\n
\n[ b1 ] = [ 9 14 11 13 ] x [ c1 ]
\n[ b2 ] [ 13 9 14 11 ] [ c2 ]
\n[ b3 ] [ 11 13 9 14 ] [ c3 ]<\/p>\nInverse ShiftRows<\/h3>\n
Inverse SubBytes<\/h3>\n
AES Key Expansion (Key Schedule)<\/h2>\n
Key Expansion Process<\/h3>\n
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Why AES cryptography is Highly Trusted<\/h2>\n
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Real-World Applications<\/h2>\n
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AES in Interview Preparation<\/h2>\n
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