From 01/15/23: these represent the plan as of Summer 2023. Things have changed a lot as our team learns more but there’s still some good nuggets here!

Based on conversations with Rachel, Althea, Richard, Barry WhiteHat, and yush Originally from

An attempt to return to private ownership of content, but still digital-native. A world in between vinyl records and Spotify. A future enabled by signatures and ZK. A tactile and smooth interaction powered by NFC chips.

Things in bold are deliverables we need to perform initial user research at SBC.

Reasons for existing

  1. Enables more intimate, human interactions in an increasingly digital and artificial world
  2. Tactile representation of private data ownership and the capability of ZK
  3. Efficient & folding friendly ZK proofs with Baby jub jub signatures
  4. Improves on-boarding experience to Ethereum
    • Can make a wallet once you collect enough of these signatures to do useful/interesting things on-chain
    • Don’t need to already have a wallet to start collecting, but get similar guarantees
  5. Operational security & liveness
    • Many NFC solutions use AES encryption chips as they are cheaper
    • They no longer need to maintain security of 100 symmetric encryption keys + make sure their server is up
    • Can have a smart contract that handles logic

Use cases

These are the main use cases we have identified for these cards:

  1. Private POAPs that don’t require a wallet + gas

    • Can be used for
      • Pure joy of collection, like digital merchandise
      • Loyalty programs (restaurants, artists)
      • Proof of connection in physical world
    • Events to be dployed at
      • Conferences (talks, subevents)
      • Concerts / festivals
      • Parties
      • Government events (town halls)
  2. Zupass replacement / Semaphore-equivalent identity

    • Cards with BJJ curve + PLUME + encryption key storage can do all functionality of Zupass
      • PLUME gives you Semaphore-equivalent nullifiers
      • Encryption key can encrypt/decrypt your data from some external storage, likely cloud
    • Can also have ECDH functionality for encrypted communication
  3. Private digital art / NFT replacement

    • Enable collectors to have private yet digitally meaningful pieces of digital art
    • Each signature comes with an RNG value, which if combined with generative art could give collectors their own unique pieces that no one else sees
    • No more “copy paste your NFT jpeg” meme
  4. Private dynamic signature image, using encryption

    • Allow users to upload an encrypted version of their signature image that is private
      • Receivers need to be able to decrypt; perhaps encryption key to image is also passed along
    • Can be used for contact cards / business cards at conferences
    • Can make a privacy focused version of a “close friends story”
    • Upcoming event notifications to people that went to a venue or bar or house
  5. Artist evangelism with merch that generates signatures

    • Fans have merch that gives out signatures to anyone that taps
    • Can give friends of fans a unique gift or video, or just a link to an album or the fan’s favorite song
    • Can be used to grant other permissions
      • Early access to new song
      • Early access to tickets
      • License to use an AI speech model of the artist to say a specific phrase :O

Project components

We break the project into a few key components:

  1. Where the signatures are stored
  2. Auxiliary infrastructure to the signatures like ZK proofs/verificatins
  3. Applied ZK research we need

(1) Storage solutions

Here are a few storage options for securely storing signatures on mobile phones, which is the primary interface users will use to interact with the NFC technology:

  1. Apple Passes
    • Stored in the Wallet app for iOS devices using the the PKPass file format.
    • Signatures sync across user’s Apple account, so that e.g. passes are also available on Apple Watch.
    • Apps are able to query for passes to generate ZK proofs on the private signatures.
  2. Google Wallet
    • Constraints are similar to Apple wallet, except needs more testing across the different Android architectures.
    • Need to move private service account key to within the browser to prevent sending signatures to a (potentially) malicious server.
  3. Cloud-based password managers
    • Comes default with most devices, and easily interoperates with mobile browsers to generate ZK proofs.
    • Can just store the list of signatures as a “password” in the password manager
      • Bit of a hijacking, but provides a decent backup
      • Don’t need to deal with setting up a secure store
  4. In-app storage
    • Non-cloud app storage is local-only and is removed with deletion of the app.
    • If on phone, can encrypt data with secure enclave ECDH
    • If on watch, can use more easily (similar to NYC metro)
  5. Cloud storage with end-to-end encryption key a. Key stored in single-write card b. Key derived from master password c. Key derived with WebAuthn PRF
    • Only available on Chrome canary right now
    • Would be great to keep an eye on as PRF expands as a framework
  6. Data stored in accessories
    • Smart accessories just as rings, chip wristbands, etc.
    • Purest solution; akin to self-custody; no storing on any server

(2) Auxiliary infrastructure

Additional components are necessary to support an end-to-end working version of Project Vinyl.

  1. ZK verifier on smart contract that gates behavior such as minting soulbound NFT
    • This could be useful for crypto conferences, for attendees to get a SBT for each of the NFC signatures they collect
    • Shows how this tech enables chain onboarding
  2. Map from public key to signature image
    • To start off, we can use a persistent database such as Postgres or Airtable.
    • For more high-stakes use cases, we’ll want to use storage on a smart contract.
  3. Web app for updating the public key to signature map
    • A simple version of this could just be the Airtable UI.
    • More complex version looks more like a custom web app that makes ethers.js calls to the smart contract.
  4. Mobile app that mimics the ability of cards, with secure enclave option
    • Can allow people to give out signatures with an incrementing nonce without cards, using QR codes initially
    • Easier to collect user feedback, maybe we don’t need cards at all
    • Worse security; if user can access private key can forge the nonce
    • If iPhones / Androids can be an NFC sender, we can mimic the exact flow of cards with phones
  5. FHE PIR lookup of images using
    • Otherwise, service hosting the images can see what images a user is requesting and break their privacy slightly

(3) Applied ZK Research

These are projects in applied ZK research that the project will require in order to generate the most interesting NFC setups.

  1. Generate Groth16 proofs for baby jub jub ECDSA signatures from the cards.
    • From spartan-ecdsa, we know takes 3,039 R1CS constraints for Efficient ECDSA verification and 17,544 for full ECDSA verification
    • This compares to 5,544 constraints in a Semaphore signalling circuit with Merkle tree depth 20
  2. Nova proofs to count and/or compute properties over multiple distinct signatures
    • Can use the bn254/grumpkin cycle to efficiently verify baby jub jub signatures
  3. Signature witness encryption to allow signature collectors to decrypt a private image
    • Could enable dynamic signature images that are private, without having to encrypt to different private keys

Scattered thoughts

From Lakshman:

  • Artists are community leaders these days
    • Online mediums have allowed them to scale their audiences faster
  • This technology allows them to interact more closely with their people
  • An important social signal is “being part of the same tribe”
    • This often boils down to “being in the same place at the same time”
    • These sorts of attestations can power that
  • “iykyk” is an exclusive energy but also a connective one