Encryption Playground (AES-GCM)
100% PrivateSecurity & Privacy UtilitiesEncrypt short text with a passphrase using AES-GCM, and decrypt it back the same way.
Runs entirely in your browser. Your input is not uploaded to Ovatly or anywhere else.
This is a playground for learning, not a vault. For real secrets, use an audited password manager or your operating system's encrypted storage. This tool's output format (see below) only works with this tool; other apps cannot open it. And if you forget the passphrase, the text is gone for good: there is no recovery.
Output starts with OVAT1. followed by Base64 of: a 1-byte version, a random 16-byte salt, a random 12-byte IV, then the AES-GCM ciphertext (256-bit key, 128-bit authentication tag). The key is derived from your passphrase with PBKDF2-HMAC-SHA-256 at 210,000 iterations. A wrong passphrase fails the GCM tag check, which is why you get a plain could-not-decrypt message instead of garbled text.
- 1Type the text and a passphrase on the Encrypt tab, then press Encrypt.
- 2Copy the OVAT1. text; that single string carries the salt, IV and ciphertext together.
- 3Switch to Decrypt, paste the string, enter the same passphrase.
- 4Press Decrypt to get your text back, or try a wrong passphrase to see the failure message.
The string OVAT1.AY2T35LSmwcqthg/FH3lhifhB29/Ni7STzQzPHDt3yhv5oZBPZGgi2TiokVf9rEH8Xv7qb3j7jgB40e+fhDRKa6qfyllxLc= was produced by this tool from the note Meet at the old depot at 9 with the passphrase library card. Paste it into the Decrypt tab with that passphrase and you get the note back; any other passphrase gives the could-not-decrypt message. Your own encryptions will look different every time, because the salt and IV are random.
- The OVAT1 format is this tool's own documented layout (version byte, 16-byte salt, 12-byte IV, then ciphertext, all Base64 encoded). It is not a standard like PGP or age, so only this tool can open it.
- Key derivation is PBKDF2-HMAC-SHA-256 with 210,000 iterations, following current OWASP guidance for that algorithm; a weak passphrase is still weak, because attackers can guess passphrases offline.
- There is no recovery. A forgotten passphrase means the text is permanently unreadable, and Ovatly never sees either the passphrase or the text.
- For real secrets, use an audited password manager or dedicated encryption software instead of a web page, however carefully built.
AES-GCM attaches an authentication tag to the ciphertext. Decryption checks it first; a wrong key fails the check, so the tool can honestly report failure instead of returning nonsense.
About this tool
The Encryption Playground encrypts short text with AES-GCM, the authenticated encryption built into your browser, using a key derived from your passphrase with PBKDF2. It exists so you can see real encryption happen end to end, with every parameter shown, before trusting the idea anywhere that matters.
Related tools
Part of Ovatly's free tools in Security & Privacy Utilities.