sigill
Open app

Buy a gift card.Privately.

The chain never sees what you paid. The observer never sees the code. Only your wallet can open the envelope.

Open SigillSee it work
the app, mid-flow
We supportApp Store & iTunesLiveNetflixSpotifyGoogle PlayXbox LivePlayStationSteamRoblox
app.sigill.store/buy

Buy a gift card

Step 3 of 3
#01

App Store & iTunes · $2

2USDC
#02

Netflix · $20

Coming soon
#03

Spotify · $10

Coming soon

Sealed envelope

Product

App Store & iTunes · $2

You pay

2.505 cUSDC

Relay

0xc637…50FC

Seal & place order

The flow

How an order moves
through Sigill.

01

Pick a card

App Store & iTunes is live today; Netflix, Spotify, Google Play, Xbox, PlayStation, Steam, and Roblox are queued behind it. Whichever you pick, the product ID is encrypted in your browser before it ever touches Base.

02

Pay in cUSDC

Approve a sealed cUSDC allowance. Sigill consumes it as encrypted escrow. The amount never lands in plaintext.

03

Open the envelope

A bonded observer fulfils the order, pins an AES-encrypted code to IPFS, and wraps the AES key to your wallet. Only you can unseal it.

What goes where

Plaintext goes in.
Ciphertext goes out.

Three inputs meet the seal. Four destinations get only what they need. The encryption itself runs on Fhenix CoFHE, the engine inside the seal.

PLAINTEXT · IN

USDC

Plaintext token

PLAINTEXT · IN

Product choice

Apple, Netflix, Spotify, more

PLAINTEXT · IN

Buyer wallet

Your signer + decrypt key

THE SEAL

sigill

ENCRYPTION ENGINE

Fhenix

CIPHERTEXT · OUT

Base Sepolia

Opaque handles only

CIPHERTEXT · OUT

Observer

Decrypts product ID + paid amount

CIPHERTEXT · OUT

IPFS

AES ciphertext, gibberish on its own

CIPHERTEXT · OUT

Your wallet

Unseals the AES key, reads the code

The reveal

Wrapped to
your wallet.

The observer AES-encrypts your gift card code on the way in and pins the ciphertext to IPFS. Sigill wraps the AES key to your wallet using FHE. We never see it. The observer never sees it. Only your wallet decrypts.

Gift card · #142
???? ???? ???? ????
Sealed · awaiting your walletAES · 256

Trust

What stays
private.

  1. 01

    Encrypted in your browser

    The product ID and your sealed allowance are encrypted with Fhenix CoFHE before any transaction is signed. No server holds plaintext.

  2. 02

    Scoped decrypt permission

    FHE.allow grants the observer decrypt access to the product ID and the paid amount, nothing else. The AES key is wrapped to your wallet only.

  3. 03

    Bonded, time-bound observers

    Observers post a 0.01 ETH bond. If they miss the 10 minute deadline, you refund yourself and 50 percent of their bond is slashed.

  4. 04

    Open source on Base Sepolia

    Sigill, ConfidentialERC20, and the Observer contract are public on Base Sepolia. Read the source, verify the bytecode.

    Read on GitHub