E2E Encryption Architecture

The Server is Blind.

We function as a blind mailbox. We hold the locked boxes, but only you have the keys to open them.

Your iPhoneHas Keys
Encrypted
Cross Paste ServerNo Keys
Still Encrypted
Your Windows PCHas Keys
AES-256-GCMRSA-OAEP 2048PBKDF2-SHA-256

The Public Lockbox Architecture

How devices share secrets without the server ever knowing them.

1

The Handshake

Device B (New) creates a public/private key pair and sends the Public Key to the server.

2

The Wrapping

Device A (Existing) grabs that Public Key, encrypts the Master Group Key with it, and sends the "Locked Box" back.

3

The Unlocking

Device B downloads the Locked Box and opens it with its Private Key. The server never sees the naked Group Key.

Zero-Trust Architecture

Client-side encryption means we literally cannot read your data.

Client-Side Encryption

Your data is encrypted before it leaves your device

Data is encrypted before it leaves your device using AES-256-GCM.

We literally cannot read your clipboard history.

If the FBI asked for your data, we'd hand them a pile of scrambled characters.

// On your device
const encrypted = AES.encrypt(
"Hello from iPhone",
groupKey
)
// What our server sees
xK9#mQ2$vL7@nR4...

Cloud Sync, Zero Knowledge

A direct answer to the most common question: yes, your clipboard goes through our server—but never in a form we can read, and never peer-to-peer.

It syncs through our server

Encrypted clips travel through our backend—not peer-to-peer over your local network. That's what keeps your devices in sync across different networks and locations, even when they're not online at the same time.

Stored as ciphertext only

The server only ever holds encrypted blobs. Your keys live on your devices, so we can't decrypt anything we store—not for ourselves, an attacker, or a legal request.

Deleted on a schedule

On the Free plan, encrypted items older than 24 hours are hidden at once and deleted from our server within the next 6 hours (your most recent item is always kept). Pro history does not expire while you have Pro.

Try it on your devices.