protocol-medrec — Prometheus Chains

Solidity contracts for patient-owned medical records:

• L1 (Ethereum): append-only PatientRecord timeline (content-hash only)
• L2 (Base): encrypted storage by secret tag in a minimal Vault

Why

Healthcare’s data silos block trust and portability. Here the patient is the steward of a single source of truth:

• L1: integrity + ordering = seq, contentHash
• L2: storage + privacy = tag → ciphertext
• Device: does the crypto; plaintext never leaves the device

Contracts

• PatientRecord.sol — owner-only append; anchor(bytes32 contentHash, uint32 l2ChainId); seq, contentHashAt(i)
• PatientRecordFactory.sol — one record per address; createRecord(), recordOf(address)
• EEVault.sol (L2) — put(bytes ciphertext, bytes16 tag) → bytes32 envelopeId, plus reads by tag / id

Design highlights

• Anchor-first: canonicalize FHIR JSON (stable stringify) → sha256 → contentHash → append to L1.
• Deterministic crypto (done off-chain):
  One EIP-712 signature (session-only) → derive {tag(16), key(32), nonce(12)} from (root, recordAddr, index i); encrypt plaintext with AES-256-GCM; store to L2 by tag.
• Restore: iterate i = 1..seq, re-derive {tag,key,nonce}, fetch ciphertext, decrypt locally, verify sha256(pt) == contentHashAt(i).

Quickstart

Foundry

forge build
forge test -vv