# AES-GCM Encrypt / Decrypt

URL: https://phishdestroy.io/developer-tools/aes-gcm-encryption
Category: Personal security
Where it runs: Runs locally (nothing you enter is uploaded)

Encrypt text with AES-256-GCM and a passphrase, or decrypt a Base64 string made by this tool. The key is a single SHA-256 hash of the passphrase, so use a long random one.

## Example input

Short message

```
Meet at the usual place at 10:00.
```

Encrypt returns Base64 of a random 12-byte IV, the ciphertext and the 16-byte tag, different on every run. Type a passphrase in Password / Key first: the tool also accepts an empty one, which protects nothing.

## FAQ

### How is the key made from my passphrase?

The AES-256 key is one SHA-256 hash of the passphrase, with no salt and no slow key derivation such as PBKDF2 or Argon2. A short or guessable passphrase can therefore be brute-forced quickly offline, so use a long random one, for example from Passphrase Generator.

### What is in the output, and can other software decrypt it?

Base64 of a random 12-byte IV, then the ciphertext and the 16-byte GCM authentication tag. Decryption shows Error: wrong key or invalid data if the passphrase is wrong or any byte changed, and other software can decrypt it only with the same SHA-256 key and byte layout.

### Is my text or passphrase sent anywhere?

No. Encryption runs in your browser with the Web Crypto API; the passphrase and the text are never uploaded or stored.

## Related tools

- [Passphrase Generator (BIP39 Words)](https://phishdestroy.io/developer-tools/passphrase-generator)
- [Password Generator](https://phishdestroy.io/developer-tools/password-generator)
- [HMAC Generator](https://phishdestroy.io/developer-tools/hmac-generator)
- [Text Hash Generator](https://phishdestroy.io/developer-tools/hash-generator)
- [Base64 Encoder / Decoder](https://phishdestroy.io/developer-tools/base64-encoder-decoder)

All tools: https://phishdestroy.io/developer-tools