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zkPhoto: Private Authentic Photo Sharing

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Now launched on Harmony testnet! Try it at https://testnet.zkphoto.one

Backstory

This proposal aims to be a small stepping stone toward #2 of Brian Gu’s Six ZK Moonshots. The idea is to have an on-chain data marketplace where users can trade private data, for example, “a high-res image that downsamples to a known low-res image”, using ZK. Within the scope of this proposal, the MVP is to implement a dApp that (0) use ZK to prove that the low-res image is downsized from an actual high-res image, (1) mint an NFT that contains the downsized image, *as well as the hash of the original image, (2) implement an in-browser camera for authentic on-chain photo-taking, and *(3) a marketplace providing secured transfer of the underlying full-res image.

*=optional/nice to have

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Github repos

GitHub - socathie/zkPhoto: Private authentic photo sharing using ZKP

This project demonstrates a small stepping stone toward #2 of Brian Gu's Six ZK Moonshots. The idea is to have an on-chain data marketplace where users can trade private data, for example, "a high-res image that downsamples to a known low-res image", using ZK.

github.com

GitHub - socathie/zkPhoto: Private authentic photo sharing using ZKP

GitHub - socathie/zkPhoto-ui: frontend for zkPhoto

This project was bootstrapped with Create React App. In the project directory, you can run: Runs the app in the development mode. Open http://localhost:3000 to view it in the browser. The page will reload if you make edits. You will also see any lint errors in the console.

github.com

GitHub - socathie/zkPhoto-ui: frontend for zkPhoto

Phase 0: downsizing photo with ZKP

MVP: a verifier contract that takes a private input of the fixed-size high-res image and outputs the low-res image *and the hash of the original image

Input: an image of resolutions 1024x1024 in png format

Output: a downsized image of resolutions 64x64 and the hash of the original image

Requirements:

circuit to downsize a slice of the image and hash the slice private input: a bytes32 array of dimensions (256,256,3) that corresponds to the RGB values of 1/16 of the image of resolutions 1024x1024 outputs: a bytes32 array of length 64 corresponding to the downsized image of resolutions 16x16 bundling every 4 pixels together + a bytes 32 hash method: bilinear interpolation

~~tests in hardhat to deploy and run the verifier contract~~

~~companion javascript to read image files to turn into input format and save output format into an image file~~

Extensions:

circuits that accept other image sizes

Phase 1: NFT minting

MVP: a smart contract that mints an NFT given the downsized image and *the hash of the high-res image

Requirements of the zkPhoto smart contract

~~a method to mint a new NFT given a snarkjs proof from phase 0~~

~~a method to extract the low res image from the contract URI given an NFT id~~

~~a method to verify a local image is the original image of the corresponding NFT~~

~~a method to write string as a base 64 tokenURI~~

~~hardhat tests~~

~~avoid double minting of the same image~~

reduce gas fee

Extensions:

a stateless version of the same contract

Phase 2: on-chain photo taking

MVP: an in-browser js camera that takes a photo then mints a zkPhoto NFT directly

Requirement:

~~a frontend to upload an image and (1) mint an NFT or (2) verify that it is the original image of the NFT~~

~~a frontend to display the low-res image of a given NFT id~~

~~a frontend to compare the image in tokenURI and the data within the contract~~

Phase 3: secured transfer of private data

TBC