AES Encryption/Decryption Tool
The AES Encryption Tool lets you encrypt and decrypt text using industry-standard AES algorithms directly in your browser. Choose between AES-128-CBC, AES-256-CBC, and AES-256-GCM modes with automatic key and IV generation.
All cryptographic operations are performed locally using the Web Crypto API — no data is ever sent to any server. Generate random encryption keys, encrypt plaintext to Base64 ciphertext, and decrypt it back with the correct key and IV.
How it works
AES (Advanced Encryption Standard) is a symmetric block cipher that encrypts data in 128-bit blocks. CBC mode chains blocks using an IV, while GCM provides authenticated encryption with built-in integrity verification. Key sizes of 128 or 256 bits determine security level.
Use cases
- Testing symmetric encryption for application development
- Learning how AES encryption modes (CBC, GCM) work
- Encrypting sensitive configuration values locally
- Verifying encryption/decryption implementations
- Generating random AES keys for development and testing
Frequently asked questions
Is this AES encryption tool secure and private?
Yes. All encryption and decryption run entirely in your browser using the built-in Web Crypto API, and no plaintext, key, or ciphertext is ever sent to a server. Because the processing is local, your data never leaves your device. For highly sensitive secrets, always run the tool on a trusted, malware-free computer.
What is the difference between AES-128 and AES-256?
The number refers to the key length in bits: AES-128 uses a 128-bit key and AES-256 uses a 256-bit key. AES-256 offers a larger keyspace and is generally preferred for long-term or high-value data, while AES-128 is still considered secure and slightly faster. Both encrypt data in 128-bit blocks regardless of key size.
What is the difference between AES-CBC and AES-GCM?
CBC (Cipher Block Chaining) only provides confidentiality and chains blocks using an initialization vector (IV). GCM (Galois/Counter Mode) provides authenticated encryption, adding a built-in integrity tag that detects any tampering with the ciphertext. GCM is usually recommended for new applications because it protects against modification, not just eavesdropping.
What is an initialization vector (IV) in AES?
An IV is a random value used to ensure that encrypting the same plaintext twice produces different ciphertext. It does not need to be secret, but it should be unique for each encryption and is required to decrypt the message. This tool generates the IV automatically and you must keep it together with the ciphertext to decrypt successfully.
Can I decrypt text without the correct key and IV?
No. AES is a symmetric cipher, so decryption requires the exact same key used to encrypt, plus the matching IV. Without both, the ciphertext cannot be recovered — that is the whole point of strong encryption. If you lose the key or IV, the encrypted data is effectively unrecoverable.