What is AES encryption?

AES (Advanced Encryption Standard) is the most widely used symmetric encryption algorithm. It encrypts data in 128-bit blocks using keys of 128, 192, or 256 bits. AES-256 is considered secure against all known attacks.

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

AES-128 uses a 128-bit key (16 bytes) and 10 encryption rounds. AES-256 uses a 256-bit key (32 bytes) and 14 rounds. AES-256 provides a higher security margin but is slightly slower. Both are considered cryptographically secure.

AES Encrypt & Decrypt — AES-128 / AES-256

AES (Advanced Encryption Standard) is the global standard for symmetric key encryption, adopted by the US National Institute of Standards and Technology (NIST) in 2001. It is used in TLS/HTTPS, VPNs, disk encryption (BitLocker, FileVault), and virtually every secure communication system.

AES Modes of Operation

CBC (Cipher Block Chaining): Each block is XOR'd with the previous ciphertext block before encryption. Requires an IV. Most common mode.
ECB (Electronic Codebook): Each block is encrypted independently. Deterministic — same plaintext always produces the same ciphertext. Not recommended for most uses.
CTR (Counter): Converts AES into a stream cipher. Does not require padding. Good for random access.
OFB (Output Feedback): Similar to CTR, generates a keystream that is XOR'd with plaintext. Good for streaming data.

Frequently Asked Questions

What key size should I use?

AES-256 is the recommended choice for new applications. Both AES-128 and AES-256 are considered secure against brute-force attacks, but AES-256 provides a larger security margin for long-term data protection.

What is an IV (Initialization Vector)?

An IV is a random value that ensures identical plaintexts produce different ciphertexts when encrypted with the same key. CryptoJS generates a random IV automatically and prepends it to the output.

AES Encrypt & Decrypt online

Encrypt and decrypt text with AES-128 or AES-256 — runs entirely in your browser

AES Modes of Operation

Frequently Asked Questions

What key size should I use?

What is an IV (Initialization Vector)?