What it does Free beta

One function: receive what people send you.

Lite provides an encrypted-drop workflow. Senders drop, you host, and nothing crosses the wire in the clear.

Anonymous drops

Senders need no account or email. They use a QR invite you approve. Each drop is encrypted to your key on the sender's own device, and the sender keeps no copy.

One-way → sender to host, end-to-end

You host it, two ways

Run a personal vault across your own devices, or an organisation inbox that receives from many external senders. Both live on your device.

On your device → personal or org

Control over senders

Approve or decline each sender, set per-sender file and storage limits, and monitor storage use. Drops are stored append-only. They cannot be altered or removed without your action.

Quotas → per-sender · append-only

The app iOS · Android · desktop

Set it up in minutes. Receive from anyone you invite.

Organisation inbox

Senders & approvals

Settings & identity

Storage & quota

Capabilities in Lite today

Four properties, live in Lite.

In Lite 01 · Encryption

End-to-end, client-side

Each drop is encrypted with AES-256-GCM on the sender's machine before it is uploaded. SpaceBox stores a ciphertext bundle it cannot open.

AES-256-GCM · SBXB v2 bundle

In Lite 02 · Post-quantum

Quantum-resistant keys

Key exchange uses ML-KEM-768 (NIST FIPS 203 / Kyber). Data captured today remains protected against the cryptographically-relevant quantum machines expected in the 2030s.

ML-KEM-768 · liboqs

In Lite 03 · Non-custodial

You hold the keys

Your private key is generated locally and stored only in your device's secure storage. i46 cannot decrypt your data, and neither can a court order served on i46.

Secure storage · zero-knowledge

In Lite 04 · Passwordless

No password to steal

Login is a cryptographic challenge: the server encapsulates a secret to your public key and only your device can recover it. No password or shared secret leaves your machine.

KEM challenge–response

The life of a drop step through it

From the sender's device to yours.

Your device

creates an ML-KEM-768 keypair

↓ one keypair, two halves

Private key

secure storage · never transmitted

On device

Public key

leaves only to register

Step 01 · keypair

Keys are generated locally

The first time you host a SpaceBox, your device generates an ML-KEM-768 keypair. The private key is written to your device's secure storage and never transmitted.

OQS_KEM_ml_kem_768_keypair() · device secure storage

Your device

sends a display name + public key

↓ public key only · no password

Server

learns nothing that can decrypt

Step 02 · register

Only the public half leaves

Registration sends your public key and a display name. There is no password and no private material. The server learns nothing that could decrypt your drops.

POST /api/users · auth_public_key

Server challenge

a random secret sealed to your public key

↓ only your private key can open it

Your device proves it

no shared secret crosses the wire

Verified

Step 03 · login

Proof without a password

To sign in, the server encapsulates a random secret to your public key. Only your private key can decapsulate it, which proves your identity. No shared secret crosses the wire.

/api/auth/challenge → decaps → /verify

Sender's file

plaintext, on their machine

↓ AES-256-GCM · key wrapped to yours

SBXB v2 bundle

sealed to your key before it leaves

Sealed

Step 04 · encrypt

The drop is encrypted on the sender's machine

A sender you have approved encrypts each file with a fresh AES-256-GCM key, then wraps that key to your ML-KEM-768 public key, producing the SBXB v2 bundle. Plaintext never exists outside their device.

AES-256-GCM + ML-KEM wrap · sealed to host

Sealed bundle

lands in your inbox

↓ stored verbatim · append-only

Your SpaceBox

ciphertext only · noise without your key

Step 05 · store

Your SpaceBox holds only ciphertext

The opaque bundle lands in your inbox and is stored verbatim, append-only, alongside its metadata. Compelled or breached, all anyone obtains is noise without your private key to match.

append-only SBXB blob · zero-knowledge

Ciphertext

pulled from your inbox

↓ decrypted on your device

Plaintext

exists only on your device

Only you

Step 06 · open

Open it on your device

When a drop arrives you decapsulate the wrapped key with your private key and decrypt the file locally. The plaintext exists only on your device, never on the server and never with us.

decaps → AES-256-GCM open · local only

Three guarantees core principles

i.

Zero-knowledge

Encryption happens on the device. The server stores ciphertext and metadata only; it never holds a key that could open it.

ii.

Post-quantum

ML-KEM-768 key exchange with AES-256-GCM bodies, resistant to harvest-now-decrypt-later attacks.

iii.

Non-custodial

Your private key lives in your device's secure storage and never leaves it. No back door, no reset, no master key.

Legal limits what we can produce

What a court order to i46 cannot produce.

×

Your drops

We hold ciphertext. Without your private key, which we never receive, it stays unreadable, even to us.

×

Your password

There isn't one. Authentication is a key-exchange challenge, so there's no credential to seize or reset.

×

A back door

Your private key lives only in your device's secure storage. There is no master key and no support path that can open a SpaceBox.

The primitives for the cryptographers

Key encapsulationML-KEM-768. NIST FIPS 203 (Kyber), via liboqs. 1184 B public key, 1088 B ciphertext.

Content encryptionAES-256-GCM. 256-bit key, 96-bit nonce, 128-bit auth tag.

Bundle formatSBXB v2. One independent AES-GCM entry per host; the key is wrapped under the host's ML-KEM public key.

AuthenticationKEM challenge–response. The server encapsulates to your public key; you decapsulate to prove identity. No passwords.

SendersAnonymous. A device-generated ML-KEM keypair, invited by QR or link and approved by the host. No account, no email.

Key custodyDevice secure storage (Keychain / Keystore); a 24-word recovery phrase arrives with SpaceBox Ground.

TransportTLS to spacebox.i46.cz; the payload is already end-to-end encrypted beneath it.

Post-quantum · non-custodial · anonymous drops · in the free Lite beta today.

Get started

SpaceBox Lite is free, and out now.

Turn your device into a SpaceBox in a few minutes. Keys are generated on-device, drops are sealed before they reach you, and there is nothing for us to hand over.

Get SpaceBox Lite → How the crypto works

The full vault (two-way sharing, ownership transfer, digital inheritance and 24-word recovery) is SpaceBox Ground. Orbital storage is SpaceBox Space.

Receive files, encrypted on the sender's device.