cipher core

This is the repo of cipher, an artwork by Paul Seidler. If you are interested in experimenting with ZK-encrypted data on-chain, head over to the Geheimnis Repository, which is a better starting point because it generates clean circuits and contracts.

Cipher is already opinionated toward encrypting and verifying specific Turmite data, so use this repo only if you are interested in understanding Cipher — otherwise head over to Geheimnis Repository.

The main part of cipher is an ERC-721 extension that stores encrypted metadata on-chain and enforces zero-knowledge proof-verified re-encryption on every transfer.

Token metadata is encrypted using Poseidon symmetric encryption, keyed via ECDH on the Baby Jubjub curve. Standard transferFrom is replaced by verifiedTransferFrom, which requires a Groth16 proof that the sender correctly decrypted the old ciphertext and re-encrypted it for the new owner — without revealing the plaintext on-chain. An additional reCipher operation lets the owner re-encrypt their data under a new keypair at any time.

See EIP-XXXX.md for the full technical specification.

Mainnet deployments

Contract	Address
EncryptedERC721	0x0fbc8f60cdfc6412f7068c3d71041e2c1f78ed7d
CipherMinter	0xff158f4b0b1d71b6d666747df79c47325fcf29b4
Groth16Verifier (transfer)	0xe8fad310055f8607e3afd15c05d8b1c794e78afd
Groth16Verifier (recipher)	0x0820baedf4418a84f66ede6b555eca2ff3327cbe
renderMetadata	0x7963f1a78c989e0c55732a3ab20aaabd3b17a5cc
NFTMarketplace	0x25f77d92b771cfa7ddf5944bbc0c4e688e2f4ee7

Repo structure

cipher/
├── circuits/       ZK circuits and proof generation scripts
│   ├── circuits/   Circom source files
│   ├── scripts/    Circuit build scripts (compile + trusted setup)
│   └── calldata/   Pre-generated proof calldata examples
└── contracts/
    ├── src/        Solidity contracts
    ├── script/     Foundry deploy scripts
    └── test/       Foundry tests

Requirements

• Node.js + npm
• Foundry
• circom (for circuit compilation)

Setup

make install

Build

make build           # build circuits then contracts
make build-circuits  # circuits only
make build-contracts # contracts only (forge build)

Circuit compilation downloads a Powers of Tau file and runs the Groth16 trusted setup — this takes several minutes the first time.

Test

make test

Proof generation

Runs a full simulation of the mint → transfer → recipher flow and writes proof artifacts to circuits/build/:

make generate-proofs

Circuit files

Config

• circomkit.json — circomkit include paths
• circuits.json — declares the two circuits with their template names and public signal lists
• package.json — npm dependencies and build scripts

Circuit source (circuits/circuits/)

• ecdh.circom — ECDH shared key derivation on Baby Jubjub. Takes a private key + public key, outputs the shared secret point
• poseidon-cipher.circom — Poseidon symmetric encryption/decryption over BN254, operating on blocks of 3 field elements
• poseidon-constants-old.circom — Poseidon MDS matrix and round constants, used by poseidon-cipher.circom
• ecdh-poseidon-cipher.circom — main circuit logic combining ECDH + Poseidon. Contains the deployed templates: EcdhPoseidonCipherKeyDerivationTransfer (transfer) and EcdhPoseidonEncrypt/Decrypt (used by add-new-data)
• verification-encoded-data.circom — validates the encoded Turmite slot data and wraps the ECDH+Poseidon operations for mint/recipher. Contains AddNewDataEncryptWithOptionalCheck which enforces an optional "only one slot value changed" constraint

Entry points (circuits/circuits/main/)

• ecdh-poseidon-key-derivation-cipher-transfer.circom — entry point for the transfer verifier
• add-new-data-encrypt-with-check.circom — entry point for the mint/recipher verifier

Build scripts (circuits/scripts/)

• buildEcdhPoseidonKeyDerivation.js — compiles the transfer circuit, runs Groth16 trusted setup, generates a proof with test inputs
• buildAddNewDataEncryptWithCheck.js — same for the mint/recipher circuit

JS utilities

• cryptoUtils.js — key generation, ECDH shared key derivation, JSON file reading
• encodingUtils.js — encode/decode the three 256-bit slot values storing Turmite state (positions, rulesets, color, parameters) as packed hex strings
• generateProofData.js — end-to-end simulation of mint → transfer → recipher → transfer-without-recipher, generating all four proof artifacts