What's the difference between AES-256 and AES-128?

AES-256 uses a 256-bit key, offering stronger resistance to brute-force attacks compared to AES-128.

Why is an IV (Initialization Vector) required?

The IV ensures that encrypting the same plaintext with the same key produces different ciphertext each time, preventing pattern-analysis attacks.

AES-256-CBC Encryption / Decryption

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Built for developers, this tool runs 100% locally in your browser. Your key and plaintext never leave your device — there is no backend database, keeping every test fully compliant with data-security best practices.

Key (Hex, 64 chars = 32 bytes)

IV (Hex, 32 chars = 16 bytes)

Text to process

Result

Waiting for input...

FAQ

Q: Is this online tool safe to use?

A: Yes. All encryption/decryption runs purely in client-side JavaScript, meaning every operation happens on your own computer — no data is ever uploaded to a server.

Q: Why does the encrypted output differ every time?

A: That's because of the IV (Initialization Vector). Even with identical plaintext, a different IV produces completely different ciphertext, which prevents pattern-analysis attacks.