webutilkit

Text Encryption

Encrypt text with a passphrase using AES-256-GCM, entirely in your browser. Nothing is uploaded.

Encrypted text
How it works


Your passphrase is stretched into an encryption key using PBKDF2 with
100,000 iterations and a random salt, deliberately slow to make guessing
the passphrase expensive. That key encrypts your text with AES-256-GCM,
which also detects tampering — a modified or corrupted blob fails to
decrypt rather than silently returning garbage. The salt and a random IV
are bundled with the ciphertext into one block of text, so decrypting
needs only the passphrase.


Choosing a passphrase


Since the passphrase is the only key, its strength is what determines how
hard the encryption is to break. A long, random passphrase is far harder
to guess than a short or memorable one, no matter how strong the
underlying cipher is.


What this does not protect against


This protects text at rest — in a file, a message, a note — assuming the
passphrase stays secret. It does not protect against someone who already
has the passphrase, or malware capturing what you type before it is
encrypted.
Frequently asked questions
What encryption does this use?
AES-256-GCM, with the key derived from your passphrase using PBKDF2 (100,000 iterations, a random salt) via the Web Crypto API. The salt and a random IV are bundled into the output so decrypting only needs the passphrase.
What happens if I lose the passphrase?
The text cannot be recovered. There is no backdoor or reset — the passphrase is the only key, and it is never sent anywhere or stored by this tool.
Why does encrypting the same text twice give different results?
Each encryption uses a fresh random salt and IV, so identical input never produces identical output. This is intentional: it prevents an observer from telling that two encrypted messages contain the same text.