Encrypt and decrypt text using the AES (Advanced Encryption Standard) algorithm with 128, 192, or 256-bit keys. Supports GCM, CBC, and CTR cipher modes. All encryption happens locally in your browser using the Web Crypto API.
Use a strong password. You'll need this exact password to decrypt the data.
AES (Advanced Encryption Standard) - FIPS 197
PBKDF2 with SHA-256, 100,000 iterations
Authenticated encryption with 96-bit nonce
Cipher Block Chaining with PKCS7 padding
Saved Presets is a Supporter feature.
Tool History is a Supporter feature.
Tool Notes is a Supporter feature.
Select Encrypt or Decrypt mode. Choose your key size (AES-256 recommended) and cipher mode (GCM recommended). Select your preferred output format (Base64 is more compact).
Enter a strong password. This password will be used to derive the encryption key. Use a long, random password for best security. Remember: if you lose this password, you cannot decrypt your data.
For encryption, enter the plaintext you want to encrypt. For decryption, paste the encrypted output from a previous encryption operation.
Click the Encrypt or Decrypt button. Copy the result using the Copy button. Save your encrypted data securely - and remember your password!
Your password is transformed into a cryptographic key using PBKDF2 with SHA-256. We use 100,000 iterations and a random 16-byte salt. This makes brute-force attacks extremely slow and expensive. Each encryption generates a new random salt, so the same password produces different keys each time.
AES processes data in 128-bit (16-byte) blocks. It uses a substitution-permutation network with multiple rounds of operations: SubBytes (byte substitution), ShiftRows (row shifting), MixColumns (column mixing), and AddRoundKey (XOR with round key). AES-256 uses 14 rounds of these operations.
GCM (Galois/Counter Mode) combines CTR mode encryption with Galois authentication. It produces an authentication tag that detects any tampering with the ciphertext. If someone modifies the encrypted data, decryption will fail. This is called Authenticated Encryption with Associated Data (AEAD).
The encrypted output contains: salt (16 bytes) + IV (12 or 16 bytes) + ciphertext + auth tag (GCM only). This is encoded as Base64 or Hex for easy copying. The salt and IV are stored with the ciphertext because they're needed for decryption but aren't secret.
This tool uses the browser's native Web Crypto API, which provides cryptographic operations implemented in the browser's secure context. This is more secure than JavaScript crypto libraries because the implementation is written in native code and has been extensively audited.
AES (Advanced Encryption Standard) is a symmetric block cipher algorithm adopted by the U.S. government as a standard for encrypting classified information. It's one of the most secure and widely-used encryption algorithms, supporting key sizes of 128, 192, or 256 bits. AES-256 is considered secure against all known attacks including quantum computing.
