OneFreePlace
TOOL #374 · AUTHENTICATED ENCRYPTION WORKBENCH

AES Encrypt / Decrypt

Encrypt text or files locally with modern AES-GCM, exact byte controls, authenticated metadata, portable envelopes, PBKDF2 passphrase derivation, raw-key workflows and a clearly isolated AES-CBC compatibility mode. Nothing is uploaded.

AES-GCM authenticated encryptionAES-128 / 192 / 256PBKDF2-SHA-256Raw keys + secure generationAAD + tag controlsPortable JSON envelopeLocal file encryptionTamper detection100% local

Plaintext / bytes

exact input

Key material

Passphrase
A fresh random salt is generated for every encryption and stored with the envelope.

Additional authenticated data (AAD)

authenticated · not encrypted

GCM decryption requires the exact same AAD. The envelope stores it as Base64URL so byte identity is preserved.

Mode—
Plain bytes—
Cipher bytes—
IV bytes—
Tag bytes—
Key fingerprint—

Raw components

IV / nonce
—
Ciphertext
—
Auth tag
—
PBKDF2 salt
—

Security audit

Fresh IV generatedEach encryption receives new random IV bytes.
Authenticated mode by defaultAES-GCM protects ciphertext integrity and optional AAD.
No key in envelopeThe portable envelope contains parameters, never your passphrase or raw key.

Encrypted envelope

Waiting

Decryption secret

Envelope inspector

Status
Paste an envelope and inspect it.

Encrypt a local file

Uses AES-GCM and the key settings from the Encrypt tab. The result is a portable .ofpaes.json file containing encrypted bytes and metadata.

No file selected.

Decrypt an .ofpaes file

Select an envelope file created by this tool. The secret comes from the Decrypt tab, so you can inspect exactly which key material is being used.

No envelope selected.
File operations happen in memory in your browser. For very large files or production archival encryption, use a streaming file-encryption tool designed for that workload.

Web Crypto · raw key · AES-GCM

Node.js · AES-GCM
Envelope contract
Portable design rule
The envelope records algorithm, IV, ciphertext, authentication tag, optional AAD and KDF parameters. It deliberately excludes the secret. Keep the envelope and secret separate.


Use GCM for new designs
AES-GCM combines encryption and authentication. Reusing an IV with the same key is dangerous, so this tool generates fresh random IVs automatically.
AAD is authenticated metadata
AAD is not hidden, but any modification causes GCM authentication failure. It is useful for protocol versions, record IDs or contextual metadata.
Passphrases need a KDF
Human passwords are not AES keys. The passphrase workflow derives a fixed-length key with PBKDF2-SHA-256 and a fresh random salt stored in the envelope.
CBC compatibility mode
AES-CBC is included for interoperability only and does not provide integrity by itself. Pairing CBC with authentication is protocol work; do not invent a new CBC construction.
Privacy
Encryption, decryption and file processing are performed locally using the browser Web Crypto API. The package contains no analytics or network dependencies.
Key recovery
There is no recovery mechanism. If you lose the raw key or passphrase, the tool cannot decrypt your data.