What is the Advanced Encryption Standard (AES)?
The Advanced Encryption Standard (AES) is a symmetric encryption algorithm used by governments, corporations, and security software to protect highly-sensitive data.
AES encryption converts plain text or data into encrypted and secure ciphertext. The data is encrypted by the sender and can only be decrypted by the intended recipient.
AES is a symmetric cipher, which means it uses the same key for both encryption and decryption. AES is considered the industry standard for symmetric cipher encryption because it is fast and basically unbreakable.
If data that’s encrypted using AES is intercepted during transmission, it can’t be read or used without the encryption key.
AES was developed by The National Institute of Standards and Technology (NIST) to replace the Data Encryption Standard (DES) after it became vulnerable to modern brute force attacks.
The National Security Agency (NSA) then approved the AES encryption algorithm to protect the most sensitive government data.
Here’s a comparison of AES and DES based on their most important attributes:
|Year of Introduction||2001||1977|
|Key Length||128, 192, 256 bits||56 bits|
|Block Size||128 bits||64 bits|
|Structure||Substitution–permutation network||Feistel cipher|
|Security||Considered secure for most purposes||Vulnerable to brute-force attacks|
|Performance||Slower than DES due to larger block size, but more secure||Faster but less secure|
|Use Cases||Broad use in government, commercial sectors for secure data||Limited use, often replaced by AES or 3DES|
|Developed By||National Institute of Standards and Technology (NIST), USA||National Bureau of Standards, USA|
|Known Attacks||Side-channel attacks, Related-key attacks (under certain conditions)||Brute force, Differential cryptanalysis, Linear cryptanalysis|
The Different Types of AES: Key Lengths Explained
In cryptography, “key length” refers to the size of the secret key used in an encryption algorithm. The key is measured in “bits” and determines the output of the encryption function.
Key length is directly related to the strength of the security provided by the encryption algorithm.
In general, the longer the key, the more secure the encrypted data. A longer key means that there are more possible keys that an attacker would have to try in order to break the encryption.
AES makes use of three different encryption key lengths:
- 128-bit key length
- 192-bit key length
- 256-bit key length
At the simplest level, these three key lengths represent increasingly more robust levels of encryption, with AES-256 being the most secure.
The numbers 128, 192, and 256 represent the number of plaintext blocks the algorithm can turn into ciphertext. For example, AES-256 can turn 256 plaintext blocks into 256 ciphertext blocks, applying different cryptographic keys to each block.
When the AES algorithm converts data into ciphertext, the conversion is done in rounds; 10 rounds for the 128-bit key length, 12 for the 192-bit, and 14 rounds for 256-bit.
Here’s a diagram explaining this process:
The more rounds of encryption the plaintext goes through, the more difficult it is for someone without the correct decryption key to access the encrypted data. That’s what makes 256-bit the most secure version of AES.
Where Is AES Encryption Used, and What For?
AES is an open standard, which means it is freely available for use by public and private companies for both commercial and non-commercial use.
Originally, AES was established by The National Institute of Standards and Technology (NIST) and ratified by the NSA to secure government and military data marked Secret or Top Secret.
Since it’s an open standard, it has since been adopted by a wide range of companies and organizations, including major corporations, VPN services, global banks, national security organizations, and the military. Companies like Google, AWS, Oracle, and IBM all use AES to secure their data.
AES is also commonly used to protect customer payment data and other sensitive information in mobile apps. WhatsApp, Snapchat, and Facebook messages are all encrypted using AES.
As of 2023, AES encryption has now become the standard for secure encrypted browsing and general file encryption.
Is AES the Best Encryption Method?
There’s a lot to consider when comparing AES to other encryption methods, including performance, compatibility, and the specific requirements of a given application.
Generally speaking, AES is considered to be one of the most secure and practical options in most cases. The “most secure” cipher can depend on the specific use-case, but the gold standard for symmetric-key encryption is generally AES-256.
AES-256 has become the industry-standard for encryption because it remains impervious to brute-force attacks, even after over 20 years.
AES is also easy to implement, making it popular with businesses and developers. It requires less computational power than most alternatives, which means it’s exceptionally efficient at encrypting large amounts of data.
Other commonly used algorithms include 3DES and RSA, but these serve different purposes. Here’s a table comparing the AES algorithm to other similar forms of encryption:
|Encryption Algorithm||Type||Key Sizes||Applications||Pros||Cons|
|AES (Advanced Encryption Standard)||Symmetric||128-bit, 192-bit, 256-bit||Secure storage, Secure data transmission, U.S. Government for encrypting classified information||Very secure, Fast, Efficient, Approved for sensitive government data||Vulnerable to side-channel attacks in certain implementations|
|3DES (Triple Data Encryption Standard)||Symmetric||168 bits (effectively 112 bits due to meet-in-the-middle attacks)||Finance, Some Microsoft offerings||More secure than DES||Slower than AES, Less secure than AES, Set to be retired|
|RSA (Rivest–Shamir–Adleman)||Asymmetric (public key)||Up to 4096 bits||SSL/TLS, Digital signatures, Secure email||Can be used for encryption and digital signatures, Doesn’t require key sharing||Slower than symmetric algorithms, Large key sizes|
|ECDSA (Elliptic Curve Digital Signature Algorithm)||Asymmetric (public key)||Variable, based on the chosen curve||SSL/TLS, Bitcoin and other cryptocurrencies, SSH||More efficient than RSA at equivalent security levels||More complex, Potential issues if curve parameters aren’t chosen carefully|
3DES — or “Triple DES” — is another symmetric key algorithm that was developed as a more secure version of DES. It works by running the data through the DES algorithm three times with three different keys.
3DES is slower than AES and is no longer considered as secure. While it’s still used in some sectors like finance, it’s expected to be retired soon.
RSA, on the other hand, is a public-key encryption algorithm and is used in different contexts compared to AES. It’s typically used for secure data transmission rather than data encryption at rest. The gold standard for public-key encryption is RSA-4096.
It’s important to note that the security of these algorithms also depends heavily on proper implementation and key management. AES, for instance, is considered secure, but various implementations have been subject to side-channel attacks.
It’s worth noting that this is a simplified comparison, and it does not cover all aspects of these encryption methods. Their actual security and performance can depend heavily on the circumstances of how each algorithm is implemented and used — the “best” method often depends on the specific requirements of the application in question.