AES Encryption

Encrypt and decrypt text using AES-256 encryption algorithm.

Secret Key (password)

Plain Text

Result

What is AES Encryption?

AES (Advanced Encryption Standard) is a symmetric block cipher adopted by the U.S. National Institute of Standards and Technology (NIST) in 2001. It is the most widely used encryption algorithm in the world, securing everything from HTTPS traffic to encrypted hard drives. AES operates on fixed 128-bit blocks of data using keys of 128, 192, or 256 bits. This tool uses AES-256, which provides the highest security level.

AES Modes of Operation

CBC (Cipher Block Chaining) — Each block is XORed with the previous ciphertext before encryption. Requires an IV. Used in this tool.
GCM (Galois/Counter Mode) — Provides both encryption and authentication. Recommended for modern applications.
ECB (Electronic Codebook) — Simplest mode but insecure — identical plaintext blocks produce identical ciphertext.
CTR (Counter Mode) — Turns AES into a stream cipher. Efficient and parallelizable.

Security Best Practices

Use a strong, random secret key — avoid simple passwords
Never reuse the same IV (initialization vector) with the same key
Store keys securely — never hardcode them in source code
Use authenticated encryption (AES-GCM) to detect tampering
For password-based encryption, derive keys with PBKDF2 or Argon2

Frequently Asked Questions

What is the difference between AES-128 and AES-256?

AES-128 uses a 128-bit key (16 bytes) and AES-256 uses a 256-bit key (32 bytes). AES-256 provides a higher security margin, but both are considered secure against all known attacks. AES-128 is slightly faster.

Is the encryption done on the server?

No. All encryption and decryption is performed entirely in your browser using the Web Crypto API. Your secret key and plaintext are never transmitted to any server.

What happens if I lose my secret key?

AES encryption is mathematically unbreakable without the correct key. If you lose your secret key, the encrypted data cannot be recovered by anyone — including us.

Can I use this for production encryption?

This tool is designed for testing and learning. For production systems, use established libraries like OpenSSL, libsodium, or your language's built-in crypto modules, and follow your platform's security guidelines.