“`html

In today’s digital landscape, it is crucial to safeguard our data. The Advanced Encryption Standard (AES) is among the most widely utilized and reliable encryption techniques for securing data or information. Whether you need to surf the web, perform online transactions, or protect your personal files, AES aids in keeping your information secure. It is intended to supersede the obsolete DES algorithm, which lacks resistance against contemporary attacks due to modern technologies.

This article will cover essential aspects of AES encryption, including its functioning, varieties, applications, characteristics, and how it stacks up against other encryption mechanisms like DES and RSA.

Table of Contents:

• What is Advanced Encryption Standard?
• History and Development
• Key Features of AES
• Types of AES
  • AES-128
  • AES-192
  • AES-256
• How does AES work?
• Why is AES Important?
• Applications of AES
• Differences Between AES and DES
• Attacks on AES Encryption
• How to Prevent Attacks on AES Encryption
• AES vs. RSA
• Conclusion

What is Advanced Encryption Standard?

AES refers to the Advanced Encryption Standard. It is a technique employed to safeguard digital information by transforming it into an incomprehensible format without the appropriate key. AES is a variant of symmetric encryption, wherein the identical secret key serves for both encryption (locking) and decryption (unlocking) processes. As a result of this characteristic, AES is both swift and effective in securing data.

AES was created to substitute the antiquated DES (Data Encryption Standard) and received formal endorsement from the U.S. government in 2001. It is now prevalent in various sectors of the technological realm, including secure online banking and shopping, protecting Wi-Fi networks, files, and personal data, among others.

History and Development

Prior to the advent of AES, DES was the encryption solution in that era of computing. However, as modern computers evolved, the necessity for a new encryption standard emerged in the 1990s when DES was considered vulnerable. In 1997, NIST launched a public contest to establish a superior encryption standard. After evaluating numerous proposals, the Rijndael algorithm, devised by Belgian cryptographers Vincent Rijmen and Joan Daemen, was chosen as the basis of AES. Subsequently, AES was officially published as FIPS PUB 197 in November 2001.

Key Features of AES

1. Symmetric Block Cipher: AES employs the same key for both encryption and decryption, enhancing speed and efficiency.
2. Block Size: AES is fixed at 128 bits.
3. Key Sizes: Available options include 128, 192, or 256 bits catering to various security levels.
4. Number of Rounds:

• 10 for 128-bit keys
• 12 for 192-bit keys
• 14 for 256-bit keys

5. High Performance: It is effective across a broad spectrum of hardware and software.
6. Robust Security: AES is impervious to all recognized practical attacks when applied properly.

Types of AES

There are three primary types of AES that are utilized in contemporary technology.

1. AES-128

The key and block sizes are 128 bits (16 bytes) each, featuring 10 rounds of encryption. AES-128 is reliable and robust for most applications. It is quick and effective on the majority of hardware. Commonly, it is employed in Wi-Fi encryption (WPA2), TLS/SSL, disk encryption, and secure communication protocols. AES-128 strikes a favorable balance between security and speed, making it suitable for most everyday encryption requirements.

2. AES-192

The key size is 192 bits (24 bytes), while the block size remains 128 bits (16 bytes). It consists of 12 rounds of encryption. AES-192 is more secure than AES-128 and offers greater resistance to brute-force attacks. It is slightly slower than AES-128 because of the additional rounds and larger key size. This variant is utilized in devices that demand enhanced security compared to AES-128, albeit with moderate performance. AES-192 delivers a commendable level of security and speed that lies between AES-128 and AES-256.

3. AES-256

The key size is 256 bits (32 bytes), and the block size is 128 bits (16 bytes). It comprises 14 rounds of encryption. It features the
“““html
highest level of security among AES variations and exhibits remarkable resilience against brute-force attempts. Its performance is slower than both AES-128 and AES-192, owing to the increased number of rounds and a larger key length. AES-256 is commonly utilized in fields requiring high-security measures, including governmental, military, and financial sectors. It delivers the most robust encryption and is the preferred choice when top-tier security is necessary.

How does AES operate?

AES functions by transforming human-readable data into incomprehensible code with the assistance of a secret key. It encrypts information into fixed-size blocks of 128 bits. The key used varies according to the required security level. The procedure initiates with the expansion of the secret key into multiple round keys. The data undergoes an initial round where it is combined with the first round key. AES operates on a 4*4 matrix of bytes. There are several additional rounds during which each byte is processed through tasks like substitution, row shifting, column mixing, and round key addition. The final round finalizes the encryption process without the mixing of columns.

To retrieve the original data, the identical procedures are conducted in reverse sequence utilizing the same secret key, allowing the original data to be accessible with the key.

The steps involved in AES include:

1. Sub-Bytes
2. Shift Rows
3. Mix Columns
4. Add Round Key

Let’s explore its operation with an example.

Initially, we will take an input and a secret key to comprehend the operational process step-by-step.

Input: “HELLO123WORLD456”

Secret key: “MYSECRETKEY12345”

Step 1: Transform Plaintext or Input into a 4×4 Byte Matrix (State)

Each character is converted to its ASCII byte representation and organized into a 4*4 matrix.

The input in hexadecimal is:

48 45 4C 4C 4F 31 32 33 57 4F 52 4C 44 34 35 36

And,

Key in hexadecimal is:

4D 59 53 45 43 52 45 54 4B 45 59 31 32 33 34 35

Now, the 4*4 input matrix is

And, the 4*4 key matrix is

Step 2: AddRoundKey (Initial Round 0)

Each byte of the state (input) matrix is XORed with the corresponding byte of the key matrix.

Let’s carry this out column by column.

For column 1:

Input	Key	XOR Result
48	4D	05
45	59	1C
4C	53	1F
4C	45	09

For column 2:

Input	Key	XOR Result
4F	43	0C
31	52	63
32	45	77
33	54	67

For column 3:

Input	Key	XOR Result
57	4B	1C
4F	45	0A
52	59	0B
4C	31	7D

For column 4:

Input	Key	XOR Result
44	32	76
34	33	07
35	34	01
36	35	03

The final resultant matrix (after AddRoundKey) is:

This matrix now becomes the new AES state that will progress through subsequent stages (SubBytes, ShiftRows, etc.) for Rounds 1-10.

Step 3: 9 Main Rounds, each comprising of 4 steps

Now, the following 4 steps will be executed across the 9 rounds.

Sub-Step 1: SubBytes

During this phase, each byte is substituted with its associated value in the AES S-box.

The AES S-box is a 16*16 matrix containing hexadecimal values.

“““html

	0	1	2	3	4	5	6	7	8	9	A	B	C	D	E	F
0	63	7C	77	7B	F2	6B	6F	C5	30	01	67	2B	FE	D7	AB	76
1	CA	82	C9	7D	FA	59	47	F0	AD	D4	A2	AF	9C	A4	72	C0
2	B7	FD	93	26	36	3F	F7	CC	34	A5	E5	F1	71	D8	31	15
3	04	C7	23	C3	18	96	05	9A	07	12	80	E2	EB	27	B2	75
4	09	83	2C	1A	1B	6E	5A	A0	52	3B	D6	B3	29	E3	2F	84
5	53	D1	00	ED	20	FC	B1	5B	6A	CB	BE	39	4A	4C	58	CF
6	D0	EF	AA	FB	43	4D	33	85	45	F9	02	7F	50	3C	9F	A8
7	51	A3	40	8F	92	9D	38	F5	BC	B6	DA	21	10	FF	F3	D2
8	CD	0C	13	EC	5F	97	44	17	C4	A7	7E	3D	64	5D	19	73
9	60	81	4F	DC	22	2A	90	88	46	EE	B8	14	DE	5E	0B	DB
A	E0	32	3A	0A	49	06	24	5C	C2	D3	AC	62	91	95	E4	79
B	E7	C8	37	6D	8D	D5	4E	A9	6C	56	F4	EA	65	7A	AE	08
C	BA	78	25	2E	1C	A6	B4	C6	E8	DD	74	1F	4B	BD	8B	8A
D	70	3E	B5	66	48	03	F6	0E	61	35	57	B9	86	C1	1D	9E
E	E1	F8	98	11	69	D9	8E	94	9B	1E	87	E9	CE	55	28	DF
F	8C	A1	89	0D	BF	E6	42	68	41	99	2D	0F	B0	54	BB	16

To replace a byte (e.g., 0x4C):

• Utilize the first hexadecimal digit (4) as the row number.
• Utilize the second hexadecimal digit (C) as the column number.
• Refer to the value in row 4, column C -> the value is 0xB3.

Thus, SubBytes(0x4C) = 0xB3.

Sub-Step 2: ShiftRows

The rows undergo shifting by varying positions within the matrix.

• 1st Row: No shift -> 6B 7E 72 38
• 2nd Row: Shift by one position to the left -> 85 67 C5 72
• 3rd Row: Shift by two positions to the left -> 2B 7C C0 F5
• 4th Row: Shift by three positions to the left -> 7B 01 85 21

Following the row shifts, the state matrix becomes

Sub-Step 3: Mix Columns

Next, each column is altered via Galois field multiplication. This is the most intricate step mathematically, utilizing the fixed matrix:

This fixed matrix is applied to every column of the matrix using XOR and multiplication operations in GF(2^3).

Therefore, after mixing the columns, the state matrix is

Sub-Step 4: AddRoundKey (Round 1 Key)

Now, take each byte and perform an XOR operation with the Round 1 Key (from the AES Key Expansion). For this explanation, we will demonstrate using an example key column to illustrate the XOR process.

Example Round 1 Key:

After that, each byte undergoes XOR with the current round key.

First Column:
12 ⊕ A1 = B3
7C ⊕ E5 = 99
“““html

35 ⊕ C3 = F6
E5 ⊕ D4 = 31

Second Column:
28 ⊕ B2 = 9A
35 ⊕ F6 = C3
E2 ⊕ 29 = CB
9B ⊕ 7E = E5

Third Column:
F5 ⊕ C3 = 36
3D ⊕ 07 = 3A
B8 ⊕ 4B = F3
82 ⊕ 5C = DE

Fourth Column:
32 ⊕ D4 = E6
F9 ⊕ 18 = E1
D8 ⊕ 8F = 57
8D ⊕ 90 = 1D

This represents the state matrix at the conclusion of Round 1.

The identical method is repeated for rounds 2 through 9.

Step 4: Final Round (AES Round 10)

The tenth round of AES (for AES-128) differentiates from the previous nine rounds because the final round does not include Mix Columns. Therefore, it consists solely of three processes: SubBytes, Shift Rows, and Add Round Key.

Consequently, the concluding matrix will be

Step 5: Output

Upon completion of the 10 rounds, the state matrix is converted into an encrypted output. This output is referred to as Ciphertext and cannot be interpreted without utilizing the same secret key.

The encrypted hexadecimal output is:
BA F9 FB 7C 8B 96 50 FA 86 3F 4A 72 4C 34 C5 7D

Significance of AES

Here are several reasons highlighting the importance of AES:

• AES safeguards sensitive data from unauthorized access.
• It delivers robust encryption that is extremely difficult to compromise.
• It operates quickly and efficiently, performing better even on low-power devices.
• AES is utilized in banking, communication, and data storage.
• It is endorsed by governments and security organizations, ensuring its safety.
• It serves as the worldwide standard for contemporary data encryption.
• AES constitutes a form of symmetric encryption, making it straightforward and rapid.

AES Applications

1. Secure Browsing: HTTPS employs AES to encrypt websites, safeguarding login credentials, banking, and personal information. It is implemented in all modern browsers to ensure secure communication.

2. Processor Security: Modern Intel and AMD processors integrate AES support for encryption and decryption at the hardware level.

3. Wireless Security: Wi-Fi encryption is achieved through WPA2 and WPA3 standards, ensuring data protection transmitted over wireless networks. It is widely used in home routers, enterprise systems, and public hotspots.

4. General File Encryption: AES is employed in transferring encrypted files among colleagues, securing data on laptops, USB drives, and external hard drives.

5. Mobile Device Encryption: Both Android and iOS implement AES for full-device encryption, protecting contacts, messages, photos, and applications. Most smartphones enforce this by default.

6. Password Management: Applications like 1Password and LastPass utilize AES to safeguard login details in an AES-encrypted vault, ensuring protection of sensitive data with a single strong password.

7. Financial Transactions: AES encrypts payment information in credit card terminals, being used in EMV chips and mobile wallets like Google Pay. It facilitates secure communication between terminals and banks.

8. Document Protection: Password-protected PDFs, Word, and Excel files leverage AES to encrypt and decrypt content and metadata. AES prevents unauthorized access, viewing, or modifications.

Comparison Between AES and DES

Attribute	AES (Advanced Encryption Standard)	DES (Data Encryption Standard)
Developed By	NIST (2001)	IBM, accepted by NIST (1977)
Key Size	128, 192, or 256 bits	56 bits
Block Size	128 bits	64 bits
Security Level	Extremely High	Low (easily breakable today)
Speed & Performance	Rapid and efficient	Slower and outdated
Rounds	10, 12, or 14 (depending on key size)	16 rounds
Encryption Structure	Substitution, followed by Permutation Network	Feistel Network
Resistance to Attacks	Robust against brute-force & cryptanalysis	Susceptible to brute-force, differential cryptanalysis
Hardware/Software Support	Widely supported, including AES-NI	Primarily historical or legacy systems
Use Cases	Contemporary encryption: Wi-Fi, VPNs, HTTPS, file encryption	Legacy systems, historical significance

Attacks Against AES Encryption

1. Brute-Force Attack

A brute-force attack is an endeavor to try every potential key. AES has such a vast key space that a brute-force attack is virtually impossible with current technology.

2. Side-Channel Attacks

Side-channel attacks primarily focus on the implementation rather than the AES algorithm itself. They measure power consumption, timing, and electromagnetic emissions, potentially revealing keys if AES is inadequately implemented.

3. Related-Key Attacks

The related-key attack exploits relationships between similar keys to uncover the encryption key. This method theoretically only applies to reduced-round variants of AES and is not practically feasible.

4. Weak Key / Password Usage

This attack occurs when predictable or reused passwords are chosen as encryption keys, rendering AES vulnerable.

5. Fault Injection Attacks

Physically manipulating devices to induce errors and extract key information constitutes a fault injection attack. Such actions can also weaken AES due to hardware flaws.

Mitigating Attacks on AES Encryption

• Utilize strong and random keys generated by secure cryptographic frameworks.
• Employ password managers for the secure storage of credentials.
• Avoid hard-coding keys within applications.
• Activate AES-NI in your system to minimize side-channel vulnerabilities.
• Adopt secure modes like GCM or CBC.
• Limit access…
  “““html
• Grant physical entry to devices through AES processes.
• Implement multifactor authentication on your device or system.
• Moreover, deploy a firewall or anti-malware application on your system.

AES versus RSA

Characteristic	AES (Advanced Encryption Standard)	RSA (Rivest-Shamir-Adleman)
Algorithm Type	Symmetric key encryption	Asymmetric key encryption
Key Function	Identical key for both encryption and decryption	Public key for encryption, private key for decryption
Performance	Extremely rapid and efficient	Slower, particularly for substantial data
Key Size	128, 192, or 256 bits	Typically 2048 or 3072 bits
Security Foundation	Substitution, hence, forms a permutation network	Grounded in the challenge of factoring large primes
Applications	Encrypting large data, files, and communications	Secure key exchanges, digital signatures
Computational Expense	Low	High
Example Applications	Wi-Fi, VPNs, disk encryption	SSL/TLS handshakes, email encryption

Final Thoughts

The Advanced Encryption Standard (AES) plays a crucial role in contemporary digital security. AES boasts commendable speed, efficiency, and strong encryption to safeguard your data. It was developed to supplant the now-obsolete DES algorithm. AES comprises three key sizes: 128, 192, and 256. Each tier of encryption offers varying levels of security across industries, from wireless communications to financial transactions. While AES is robust and effective, challenges may arise from improper AES implementation and weak user passwords. Therefore, grasping the nuances of AES, its types, operational mechanics, features, and methods to avert attacks will enhance your ability to utilize AES and protect your information more effectively.

Advanced Encryption Standard (AES) – Frequently Asked Questions

The post Advanced Encryption Standard (AES) appeared first on Intellipaat Blog.

“`