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Documentation

Using Cadence

Cadence is a self-custodial digital inheritance and wealth preservation protocol. It secures Paxos USDG and crypto wealth across generations through multi-signal proof-of-life consensus, zero-knowledge Merkle allocations, and automated yield-bearing streams.

Before you start

  • EVM-Compatible Wallet: MetaMask, Rabby, Coinbase Wallet, or any wallet supporting Arbitrum Sepolia (Chain ID 421614) or Robinhood Chain Testnet (Chain ID 46630).
  • Testnet Gas & Assets: Native testnet ETH for contract interaction gas, and Paxos USDG testnet tokens to deposit into your vault.
  • Designated Guardians: Prepare 2 or 3 trusted Ethereum addresses or email contacts to participate in the decentralized proof-of-life consensus quorum.
  • Self-Custodial Guarantee: Tokens remain exclusively in your own smart vault until the consensus quorum and grace period countdown have both irreversibly elapsed. Living owners retain 100% control at all times.

Core concepts & parameters

The core protocol primitives governing automated proof-of-life, privacy protection, and estate streaming:

Proof-of-Life Heartbeat
The periodic on-chain check-in interval (e.g. 90, 180, or 365 days). Calling checkIn() resets the countdown timestamp and confirms owner activity.
Guardian Quorum
A 2-of-3 threshold consensus managed by GuardianRegistry.sol. Guardians only attest to incapacitation after a heartbeat lapse; individual guardians cannot execute alone.
14-Day Grace Period
A mandatory buffer initiated after quorum. The owner receives automated sentinel alerts and can dismiss false-alarm claims gaslessly with an off-chain EIP-712 typed signature.
Blinded Merkle Root
Heir public keys and percentage splits are double-hashed client-side into allocationRoot. Zero plaintext heir identities or balances ever touch on-chain storage.
Cadence Streams
Autonomous streaming trusts releasing an immediate 10% emergency buffer, streaming the remaining 90% second-by-second to prevent phishing drainers and estate dumping.
Aave v3 Yield Engine
Unvested streaming balances deposit directly into Aave v3 on Arbitrum Sepolia, generating borrower-paid interest with zero cross-chain bridge exposure.
Anti-Drainer Defense
Appointed guardians or verified backup cold wallets can call pauseStream() and redirectStream() if an heir wallet is compromised.

Setting up a vault

  • Deploy Your Vault: Open the Cadence app, connect your wallet, and deploy your custom non-custodial vault instance via VaultFactory.sol. Configure your desired heartbeat cadence (e.g., 180 days).
  • Client-Side Heir Encryption: Add your beneficiaries and percentage splits. The Cadence interface asymmetrically encrypts the manifest using ECIES-secp256k1 and calculates the cryptographic Merkle root.
  • Register Guardian Quorum: Nominate 3 trusted guardians. Link email addresses or webhooks so the sentinel service can notify guardians when a heartbeat expires.
  • Deposit Assets & Activate Stream Terms: Transfer Paxos USDG or ETH into your vault and define the stream vesting parameters (immediate liquidity unlock + linear vesting duration).
  • Sign Once to Commit: Authorize the initial setup transaction. Your assets stay in your control, and you can adjust terms, deposit more capital, or check in at any time.

Settlement & claiming

Cadence replaces fragile on-chain dead man's switches with a two-phase fail-safe liquidation model designed to prevent accidental triggers during emergencies:

1. Attestation & Grace
If a check-in lapses, guardians submit attestations. When 2 of 3 confirm, a 14-day grace window begins. The owner is alerted via multiple channels and can abort the release with zero gas.
2. Merkle Proof Claim
Once grace ends, beneficiaries access the Claim Portal, decrypt their allocation package, and submit their cryptographic Merkle proof on-chain to unlock their allotment.
3. Streaming Release
The 10% emergency buffer is released immediately. The remaining 90% streams second-by-second into an autonomous smart contract, shielding heirs from drainers and market dumps.
4. Guardian Circuit Breaker
If an heir's key is compromised, guardians can call pauseStream() or redirect unvested stream outflows to a pre-registered backup cold storage address.

Verified smart contracts

Cadence contracts are verified and deterministic across testnet deployments. Inspect the verified source code directly on the respective block explorer:

Primary USDG Vault
0x07f9...525d
Paxos USDG Token
0x75ef...66fb
Consensus Engine
0xe340...8ae1
Guardian Registry
0xe09c...ade7
Vault Factory
0xac0f...8622
Beneficiary Factory
0xebbC...EbAf
Stylus WASM Verifier
0x583e...671E

Public APIs & Sentinel endpoints

Read endpoints return JSON and require no API key. Sensitive actions require cryptographic EIP-712 signatures:

GET /api/vaults
Active vault configuration, heartbeat countdown, balance commitments, and active stream status for an owner.
GET /api/monitored-vaults
Sentinel monitoring feed of vaults nearing heartbeat expiration or currently in grace period. Guardian contact info is cryptographically masked.
POST /api/bind
Binds a guardian Ethereum address to an email notification endpoint using an off-chain EIP-712 signature with lockout protection.
GET /api/proof?vault=
Generates the verified cryptographic Merkle proof for an authenticated heir to claim on-chain without exposing siblings.
POST /api/dismiss
Relays a gasless EIP-712 dismissal signature signed by the vault owner to immediately abort false-alarm grace periods.

Security & verification

  • Zero Plaintext On-Chain: Family net worth, heir identities, and percentage splits are never stored in plaintext smart contract storage. Double-hashed Merkle trees and ECIES-secp256k1 client-side encryption ensure zero forensic linkage.
  • Arbitrum Stylus WASM Verification: Merkle allocation validation implemented in Rust as a compiled WASM contract (stylus_merkle), demonstrating sub-cent gas execution and bit-for-bit equivalence with OpenZeppelin Solidity.
  • 11-Point Security Suite: The backend and sentinel services are audited with an automated test matrix covering rate limiting, EIP-712 replay resistance, brute-force lockout, timing-safe authorization, and CSP compliance.
  • Open Source & Verified: All contract source code is verified on Arbiscan, Robinhood Explorer, and Etherscan. View the full specification on GitHub.