Encryption is a key feature for securing information. Encryption is basically converting any normal yet confidential message to an encoded and unreadable format for high-security purposes. This unreadable text is known as ciphertext. There are many Encryption Algorithms available today. They include Advanced Encryption Standard (AES), Triple Data Encryption Standard (DES), Rivest–Shamir–Adleman (RSA) algorithm, Blowfish, Twofish, Secure-Socket Layer (SSL), and so on.
Advanced Encryption Standard or AES Encryption is currently the best and standard encryption used. Advanced Encryption Standard, AES 256-bit also happens to be the highest level of encryption and the strongest available today. Let’s dive into this security network to know more about Encryption and Advanced Encryption Standard or AES.
Why Encryption and Types of Encryption?
As we already know, Encryption is important for security purposes. But is that it? No. Although Encryption’s most important function is the security of confidential data, there are other reasons why we need encryption as well. They are:
Authentication:
Encryption provides authentication against fraud websites and services online. The legal websites not only have a proper and authorized SSL certificate but also the public key encryption is proof that the website’s original server owns the private key.
Privacy
Privacy is a very important and key requirement especially when it comes to personal information, messages, photos, etc. Encryption gives this guarantee of privacy. Encryption ensures that no one except authorized authorities like the legitimate recipient or the data owner himself can read or access any data. This not only protects your information from cybercriminals, hackers, spammers, and internet service providers but also from the government as well. Encryption ensures your personal data stays personal.
Regulatory Compliance
Although encryption protects your personal data, many institutions, industries, and government departments require some personal information of the user under specific guidelines. While some need it for work, other organizations work on keeping your data encrypted for maximum privacy. Regulatory compliance has legal laws, which on being broken call for legal action. HIPAA, PCI-DSS, and the GDPR are few organizations that work with these laws to provide encryption.
Security
As we already know, encryption of information protects and safeguards our data. Encryption can provide high security if in cases where the device with the information (ex. Hard disk) gets stolen or misplaced. If the device is properly encrypted, data cannot be stolen from it. Encryption also saves the device from data leaks which can be risky.
Types of Encryption
There are three types of Encryption. They are –
- Symmetric Encryption Key: Also known as Private-key cryptography or secret key algorithm. It requires the sender and receiver to have access to the same key. We generally use this method for systems that do not require any third-party intrusion, i.e., closed systems. The only drawback of this method is that both the sender and receiver have to make sure that the key is securely stored and is made available only to the required software.
- Asymmetric Encryption Key: Also known as Public-key cryptography or secret key algorithm. It uses two keys – A public key and a private key. The two keys are linked mathematically. The public key is obviously freely available to everyone, but the private key restricts itself to stay with specific people only. No matter which you choose first, the user employs one key for encryption and the other for decryption. The two keys aren’t identical but paired with each other, hence is asymmetric. Another thing to know is that symmetric encryption happens to be faster than asymmetric encryption.
- Hashing: It generates a unique signature for a fixed length of dataset/messages. To make the information easily trackable, each message has its unique and specific hash. The only purpose of hashing is data verification because once the encryption takes place, original data cannot be restored or decrypted. Although many experts don’t consider hashing as an encryption method, it is an effective method to detect the tampering of data.
Path to AES Algorithm
AES or Advanced Encryption Standard, an algorithm used for high-security purposes encrypts the electronic data established by the US National Institute of Standards and Technology. It also happens to be a replacement for the DES or Data Encryption Standard. DES is also the only predecessor of AES.
DES was the federal standard for block symmetric encryption in 1977. The DES is a symmetric key block cipher that is published by the National Institute of standards and technology. It is an implementation of the Feistel cipher. DS uses 16 rounds of Feistel structure. The key length of DES is 64 bits but the effective key length is only 56 bits. The remaining 8 bits aren’t used by the encryption algorithm.
Based on feistel cipher, DES requires:
- Round function
- Key schedule
- Any additional processing including initial and final permutation
DES also satisfies both the desired properties off block cipher these properties ensure that the cipher becomes very strong. these properties are avalanche effect and completeness. avalanche effect refers to a small change in plain text that can result in great change in ciphertext. Completeness means that each bit of ciphertext depends on a single/ multiple bits of plaintext.
The major reason for this shift from DES to AES is that AES is almost six times faster than triple DES. Another reason is that the key size of DES was very small. Although triple DES was implemented to overcome this, but it didn’t. Hence, the shift from DES to AES took place.
AES – A detailed study
The Advanced Encryption Standard is a symmetric block cipher. Originally known as Rijndael, its key features are:
- Implementation of Block Encryption.
- It is 128-bit group encryption.
- Includes key lengths of 128, 192, and 256 bits.
- It is a symmetric algorithm.
- Requires only one encryption and decryption key.
- Provides data security for almost 20 to 30 years.
- Accessible worldwide.
AES is a fast and secure encryption algorithm.
Working of AES
AES includes three blocks ciphers. Each of the cipher block encrypts and decrypts data blocks of 128 bits using the cryptographic keys of different bits. They are:
- AES-128: It uses a 128-bit key length that encrypts and decrypts blocks of messages. Requires 10 rounds**.
- AES-192: It uses a 192-bit key length that encrypts and decrypts blocks of messages. Requires 12 rounds.
- AES-256: It uses a 256-bit key length that encrypts and decrypts blocks of messages. Requires 14 rounds.
** A round includes multiple processing steps which include substitution, transposition, and mixing of the input plaintext to transform it into the final output of ciphertext.
Ciphers use the same key, the secret key for both encryption and decryption. Thus, both the parties need to know, safeguard, and use the same secret key. The key size required for encryption must be big enough such that it can’t be cracked easily by modern computers. Generally, for Confidential and Secret Level information, all the key lengths can be used. But, Top-secret level information uses either 192-bit or 256-bit key lengths only.
The first step of cipher generally is to write the data in the form of an array. Following this, multiple stages of transformation take place. The substitution of data in the substitution table is the first transformation in the AES encryption cipher. The second transformation is the shifting of data rows, and the third is the mixing of columns. In the mixing of columns, each column uses different parts of the encryption key. Let’s analyze these transformation steps in detail:
Transformation Step 1: Substitution of Data
Substitution of data basically means that each bit in the array is replaces or substituted by its SubByte. This alters the data in a non-linear way creating confusion. This confusion hides the relationship between the original message and the encrypted data.
Here Y(aa) is the SubByte of X(aa) in the array.
For example, Y(20) = S(X(20)) = SubByte of X20 in the Array.
Where, X(aa) and Y(aa) are the Array bits and S is the substitution of Byte or SubByte.
Transformation Step 2: Shifting of Data Rows
Also known as diffusion, the shifting of data happens in an increasing pattern per row, i.e, data is altered horizontally. This means that in the first row, there is no shift of data. In the second row, data shifts right to left by one column. In the third row, this data shift takes place by two columns and so on for an increasing number of columns. This implies that if we have n rows, the shift from right to left in the nth row would be by (n-1) columns.
Transformation Step 3: Mixing of Columns
In this step, a mathematical formula is applied to every key transforming it completely. There is no one specific way to obtain this diffused table. The formula/polynomials used may vary from code to code/ message to message. Here, the data is altered vertically.
Final step: Addition of Round key
After performing the 3 transformation steps, every byte of the array is given a round key. For the addition of this round key, we use the XOR gate.
This concludes a round of encryption. After every round of transformation, it is assigned a round key. This entire process occurs multiple times, i.e., after the round key is given, the process starts back from from the substuition process.
Difference between AES-128 and EAS-256
While AES-256 is more difficult for any attacks to occur, it requires more computing power resulting in slower execution. On the other hand, AES-128 is not as difficult as AES-256, but even this takes a long time to crack even with a huge amount of computing power, thus it isn’t an issue for the future; a hacker would need to use quantum computing to be able to generate any sort of attack. When power is becoming an issue for small devices, the AES-128 is more preferable.
Potential attacks possible on AES
- Related-Key attack: Occurred in 2009. Here, they attempted to crack the cipher by studying and understanding its operation using multiple different keys. This threat was to those AES systems that weren’t configured correctly.
- Known-Key attack: Occurred in 2009 as well, against AES-128 specifically. The target for this was the eight-round AES-128 instead of the ten-round making it a minor threat. Here, a known key was used to decrypt the encrypted structure.
- Side-Channel attacks: This is a major risk to the AES encryption. This picks up the leaked information from the system rather than trying to crack it directly. But this also reduces the number of possible combinations used to attack the AES. In this technique of attack, they use Reverse-engineering. The information collected is of the computing device while its performing cryptographic operations. They also use the timing information of different applications, their computation, electromagnetic leaks, audio clues, and optical information. This gives them additional information about the system and its methodology of processing the encryption. Preventing any data leak is the best prevention of this. Another method of prevention would be using randomization techniques. This removes any sort of relation between the leaked data and the cipher protected data.
Conclusion
AES is one of the most advanced and secure methods of encryption keeping in mind the fact that there are no leaks or sharing of the secret encryption key. Although there are a few loopholes that can cause attacks, they are mostly because of irresponsibility or any other reason. The Advanced Encryption Algorithm has 3 types, each with their own sets of advantages. Although all are safe, one is always better than the other and according to the usage required, they can be selected accordingly. The only most important thing to note again is keeping the encryption key safe. This is the only way to keep the data and information safe and away from hackers.
