What is AES Encryption?
AES (Advanced Encryption Standard) is one of the most widely used symmetric encryption algorithms in the world. It encrypts data using the same secret key for both encryption and decryption. Originally established by the U.S. National Institute of Standards and Technology (NIST), AES has become a global standard for securing sensitive data.
Key Features of AES:
- Symmetric Encryption: Same key for encryption and decryption.
- Block Cipher: Encrypts data in fixed-size blocks of 128 bits.
- Key Sizes: Supports 128, 192, or 256-bit keys.
- Fast & Secure: Efficient for both software and hardware implementations.
Common Uses:
- File encryption
- WiFi security (WPA2/WPA3)
- VPN connections
- Secure messaging
How AES Works
AES takes plaintext and transforms it into ciphertext using several rounds of substitution, permutation, and mixing. The number of rounds depends on the key size:
- 128-bit key → 10 rounds
- 192-bit key → 12 rounds
- 256-bit key → 14 rounds
The security of AES doesn't just rely on the algorithm — it also depends on how it's used. That's where modes of operation come in.
AES Modes of Operation
AES alone can only encrypt a single 128-bit block. To encrypt longer messages, we use modes of operation. Each mode handles data differently and is suited for different use cases.
AES Mode Comparison Table
| Mode | Pattern Security | Speed | Authenticated? | Best Use Case |
|---|---|---|---|---|
| ECB | ❌ No | ⚡ Fast | ❌ No | Rare, short data |
| CBC | ✅ Yes | 🐢 Slow | ❌ No | Files, backups |
| CTR | ✅ Yes | ⚡⚡ Fast | ❌ No | Streaming, disks |
| GCM | ✅ Yes | ⚡⚡ Fast | ✅ Yes | Web & secure apps |