What is AES?
AES (Advanced Encryption Standard) is a symmetric block cipher algorithm adopted by the U.S. government as the standard for encrypting classified information. It encrypts data in fixed-size blocks of 128 bits using keys of 128, 192, or 256 bits.
Quick Facts
| Full Name | Advanced Encryption Standard |
|---|---|
| Created | 2001 by NIST (algorithm by Daemen and Rijmen) |
| Specification | Official Specification |
How It Works
AES was established by NIST in 2001 after a five-year selection process, replacing the older DES standard. The algorithm, originally called Rijndael, was designed by Belgian cryptographers Joan Daemen and Vincent Rijmen. AES operates on a 4x4 matrix of bytes called the state, applying multiple rounds of substitution, permutation, and mixing operations. AES-128 uses 10 rounds, AES-192 uses 12 rounds, and AES-256 uses 14 rounds. It's widely used in SSL/TLS, file encryption, VPNs, and secure messaging.
Key Characteristics
- Symmetric encryption (same key for encrypt/decrypt)
- Block cipher with 128-bit block size
- Key sizes: 128, 192, or 256 bits
- Fast in both hardware and software
- No known practical attacks against full AES
- U.S. government approved for classified data
Common Use Cases
- File and disk encryption
- SSL/TLS secure communication
- VPN tunneling
- Secure messaging apps
- Database encryption
Example
Loading code...Frequently Asked Questions
What is the difference between AES-128, AES-192, and AES-256?
The numbers refer to the key length in bits. AES-128 uses a 128-bit key with 10 rounds, AES-192 uses a 192-bit key with 12 rounds, and AES-256 uses a 256-bit key with 14 rounds. Longer keys provide stronger security but require slightly more processing time.
Is AES still considered secure?
Yes, AES remains highly secure and is considered unbreakable with current technology when properly implemented. There are no known practical attacks against full AES. It is still approved by the U.S. government for protecting classified information up to the TOP SECRET level.
What is the best AES encryption mode to use?
AES-GCM (Galois/Counter Mode) is generally recommended for most applications because it provides both encryption and authentication (AEAD). CBC mode is also widely used but requires a separate MAC for authentication. ECB mode should be avoided as it reveals patterns in the data.
What is the difference between AES and RSA?
AES is a symmetric encryption algorithm, meaning the same key is used for encryption and decryption. RSA is an asymmetric algorithm using a public-private key pair. AES is much faster and used for bulk data encryption, while RSA is typically used for key exchange and digital signatures.
Why is AES called a block cipher?
AES is called a block cipher because it encrypts data in fixed-size blocks of 128 bits (16 bytes). Data larger than 128 bits is divided into blocks, and each block is encrypted separately. Different modes of operation (CBC, CTR, GCM) determine how these blocks are chained together.