What is AES?
Advanced Encryption Standard is a symmetric encryption algorithm adopted by the U.S. government and used worldwide. It's the gold standard for encrypting sensitive data, used in everything from HTTPS to disk encryption.
Also known as: Advanced Encryption Standard, Rijndael
AES replaced the aging DES standard in 2001 after a public competition. The winning algorithm, Rijndael, became AES and has proven unbreakable through two decades of intense scrutiny.
Key Sizes
- AES-128: 128-bit key (sufficient for most uses)
- AES-192: 192-bit key (rarely used)
- AES-256: 256-bit key (classified/top-secret grade)
All three are considered secure. The difference is future-proofing, not current vulnerability.
How AES Works
- Block Processing: Divides data into 128-bit blocks
- Rounds: Each block goes through multiple transformation rounds
- AES-128: 10 rounds
- AES-192: 12 rounds
- AES-256: 14 rounds
- Operations per round:
- SubBytes (substitution)
- ShiftRows (permutation)
- MixColumns (mixing)
- AddRoundKey (XOR with key)
Modes of Operation
AES encrypts fixed-size blocks. Modes handle larger data:
- GCM (Galois/Counter Mode): Authenticated encryption, most recommended
- CBC (Cipher Block Chaining): Common but needs careful IV handling
- CTR (Counter Mode): Turns block cipher into stream cipher
- ECB (Electronic Codebook): Never use - patterns leak
Where You Encounter AES
- HTTPS/TLS: Web traffic encryption
- VPNs: WireGuard, OpenVPN
- Disk encryption: BitLocker, FileVault, VeraCrypt
- File encryption: 7-Zip, most archive tools
- Messaging: Signal, WhatsApp (part of the protocol)
- WiFi: WPA2/WPA3 security
"Military-Grade Encryption"
Marketing often claims "military-grade encryption." This usually means AES-256, which is:
- Approved for U.S. classified information
- Practically unbreakable through brute force
- The actual standard, not marketing fluff
Performance
AES is extremely fast, especially with hardware acceleration:
- Modern CPUs have AES-NI instructions
- Can encrypt at gigabytes per second
- Negligible performance impact
Related Terms
Encryption
The process of converting information into a code to prevent unauthorized access. Encryption transforms readable data (plaintext) into an unreadable format (ciphertext) using a cryptographic algorithm and key. Only those with the correct key can decrypt and read the original data.
Symmetric Encryption
An encryption method where the same secret key is used for both encrypting and decrypting data. While fast and efficient, the challenge lies in securely sharing the key between parties.