Zelf Legacy: Biometric Inheritance Protocol for Base Chain

Abstract

Zelf Legacy introduces a non-custodial inheritance infrastructure for digital assets built on Base and solidity.

Users can maintain multiple self-custody wallets across trading, savings, and on-chain applications while ensuring that, in the event of post-mortem or prolonged inactivity, rightful beneficiaries can securely recover access rights without transferring assets into custody.

Instead of locking funds inside smart contracts, Zelf Legacy coordinates inheritance through programmable access-rights verification. Instead of restricting recovery to traditional seed-phrase reconstruction, Zelf Legacy coordinates on-chain recovery by triggering signature-threshold transitions or executing smart contract ownership transfers natively aligned with ERC-4337 account abstraction structures.

The system combines:

• Solidity smart contracts
• Heartbeat Protocol liveness verification
• Guardian Oracle coordination
• ZELF ID biometric identity infrastructure
• Shamir's Secret Sharing recovery architecture

No biometric templates are stored on centralized servers or databases. Assets remain in the original wallet throughout the inheritance lifecycle.

Zelf Legacy is powered by HumanAuthn, a biometric-rooted authentication and encryption primitive that regenerates ephemeral cryptographic keys from live facial verification. This architecture enables passwordless self-custody without exposing seed phrases or relying on custodial infrastructure.

The requested $50,000 grant will fund the development of:

• Solidity inheritance contracts
• Heartbeat Protocol infrastructure
• Guardian Oracle execution layer
• Base-native SDKs
• Developer tooling
• Testnet and mainnet deployment

All Base-specific infrastructure will be built natively for Solidity and open-sourced under MIT licensing.

Why This Matters for the Base Chain Ecosystem

Base Chain secures billions of dollars in self-custodied digital assets across DeFi, trading, stablecoins, and on-chain applications, yet the ecosystem lacks native inheritance infrastructure.

Without programmable inheritance mechanisms:

• assets can become permanently inaccessible
• families may lose access to funds
• long-term self-custody adoption becomes harder for mainstream users

Zelf Legacy introduces a non-custodial inheritance coordination layer designed specifically for the Base Chain ecosystem.

The protocol expands Base Chain's capabilities beyond trading and DeFi into:

• long-term digital asset continuity
• rightful ownership transfer
• programmable beneficiary coordination
• human-rooted self-custody infrastructure

This positions Base not only as an ultra-efficient, Ethereum-secured Layer 2 environment, but also as the primary foundational infrastructure for generational digital asset ownership.

What Is Zelf?

Zelf is a cybersecurity and self-custody infrastructure platform powered by HumanAuthn, a biometric-rooted authentication and encryption primitive.

Unlike traditional authentication systems that anchor trust in hardware devices or custodial databases, HumanAuthn replaces device-rooted authentication with biometric-rooted cryptographic ephemeral key regeneration.

A live biometric scan regenerates a temporary encryption key used to decrypt wallet credentials, eliminating the need for:

• seed phrases
• password storage
• custodial recovery systems
• persistent biometric templates

This creates a device-agnostic identity layer designed for self-custody, authentication, and secure digital inheritance.

Zelf is available on: Web Extension, iOS, and Android.

What Is Zelf Legacy?

Zelf Legacy addresses one of the largest unresolved problems in self-custody:

What happens to digital assets when their owner dies or becomes permanently inactive?

Most crypto inheritance systems rely on:

• custodial escrow
• multisig dependency
• smart-contract fund locking, or
• manual legal coordination

Zelf Legacy introduces a different model. Instead of transferring assets into custody, the protocol coordinates inheritance through programmable access-rights activation.

Inheritance execution only begins after:

• inactivity verification
• grace-period expiration
• beneficiary biometric verification
• government-issued identity validation

Assets remain in the original wallet throughout the entire process.

Protocol Flow Diagram

Step 1: Create an Inheritance Policy

Users activate Legacy Mode inside the Zelf app and designate beneficiaries through ZELF ID biometric identity binding.

Each beneficiary is linked to an encrypted inheritance policy that defines:

• inheritance thresholds
• beneficiary consensus rules
• legal coordination preferences
• recovery conditions

The inheritance architecture combines:

• Solidity smart contracts deployed on Base Chain
• ZELF ID biometric verification
• IPFS and Arweave decentralized storage
• Shamir's Secret Sharing recovery logic

Policy metadata is encrypted and stored off-chain while Solidity records only verification state and execution logic.

Users can configure:

• 2-of-3 or 3-of-5 recovery thresholds
• lawyer participation
• direct beneficiary execution
• multi-beneficiary inheritance structures

Step 2: Heartbeat Protocol

Zelf Legacy introduces a Heartbeat Protocol: a cryptographic liveness verification system anchored to Base smart contracts.

Instead of continuously tracking users or relying on custodial inactivity monitoring, the protocol enables periodic proof-of-life verification directly from the Zelf app.

Each heartbeat:

• verifies live user presence
• resets the inheritance inactivity timer
• emits signed on-chain events through Base contracts
• updates the inheritance execution state

The protocol is privacy-preserving by design:

• heartbeat credentials remain private
• no public inheritance registry exists
• no behavioral tracking is required
• liveness detection prevents spoofing attacks

Users define:

• inactivity windows (30 days to 24 months)
• grace periods
• inheritance activation conditions

Heartbeat history is compressed through verifiable credential architecture and Merkle-proof validation, reducing on-chain storage requirements by 100–1000x compared to traditional state storage models.

If heartbeat expiration and grace-period thresholds are reached, the inheritance execution pipeline begins.

This transforms inheritance from a manual legal process into programmable self-custody infrastructure.

Step 3: Access Rights Recovery

Once inactivity and grace-period conditions are satisfied, beneficiaries can initiate the inheritance claim process.

Claim execution requires three verification layers:

Design Principles

Zelf Legacy is designed around the following principles:

• Non-custodial by default
• Assets remain in the original wallet
• No biometric templates stored
• Privacy-preserving liveness verification
• Human-rooted authentication
• Programmable inheritance execution
• Off-chain encrypted metadata
• Base-native smart contract coordination
• Long-term cost sustainability

Technical Architecture

Five coordinated layers power inheritance execution without moving assets into custody.

The HumanAuthn engine and ZELF ID infrastructure are already operational.

The Base grant focuses on building the inheritance coordination layer natively on Base Chain, including:

• inheritance registry contracts
• Heartbeat Protocol infrastructure
• Guardian Oracle coordination
• claim verification pipeline
• Base wallet integration tooling
• developer tooling

The architecture is divided into four layers:

Security & Privacy

Zelf Legacy is designed to minimize custodial risk and centralized attack surfaces.

Key security properties include:

• no biometric templates stored
• private keys remain off-chain
• encrypted off-chain metadata
• liveness verification with spoof resistance
• programmable inactivity thresholds
• decentralized storage through IPFS and Arweave
• cryptographic claim verification through Solidity

The protocol coordinates access-right recovery without taking custody of user assets.

Why Base Chain?

Zelf Legacy aligns directly with Base Chain's strengths in:

• global consumer onboarding
• deep DeFi liquidity
• sub-cent transactions
• standard-setting OP Stack architecture

Inheritance is fundamentally a long-term digital ownership problem.

Base Chain provides the transaction scalability and ecosystem reach required to support programmable inheritance infrastructure at global scale.

Key reasons for choosing Base Chain include:

• Low transaction costs: Heartbeat verification must remain economically sustainable over years or decades.
• EVM Equivalence: Provides 100% bytecode compatibility with Ethereum mainnet, allowing seamless out-of-the-box integration with established Ethereum developer tooling, frameworks, and smart contract security standards.
• High throughput: Supports scalable heartbeat verification and inheritance coordination.
• Mature wallet ecosystem: Native compatibility with Coinbase Wallet (including Coinbase Smart Wallet), MetaMask, Trust Wallet, and standard EVM developer tooling.
• Large self-custody user base: Base Chain's active DeFi and retail ecosystem creates strong demand for long-term inheritance infrastructure.

Base Chain Integration Plan

Zelf Legacy is built purposefully to leverage Base's advanced account abstraction infrastructure, low-cost EVM log emitting, and native interoperability across the broader Ethereum Superchain.

Zelf Legacy is being designed as a Base-native inheritance infrastructure built around EVM smart contracts, event-driven execution, decentralized storage, and wallet interoperability.

Rather than adapting custodial inheritance systems, the protocol leverages Base Chain's low-cost execution environment to coordinate programmable access-right recovery at scale.

Base-Specific Building Blocks

What Makes This Base-Native

The protocol utilizes Base's native ecosystem scaling and cost-efficient execution pipeline to establish a seamless digital continuity layer for everyday crypto adopters.

The protocol is architected specifically around:

• EVM smart contracts
• Base Chain low-cost execution
• event-driven coordination
• EVM wallet interoperability
• Base ecosystem scalability
• decentralized storage integration

Base Integration Flow

Data flow showing exactly how Base components participate in the inheritance lifecycle:

Open Source Commitment

All Base-specific infrastructure developed through this grant will be released under MIT licensing, including:

• Solidity smart contracts
• Heartbeat Protocol infrastructure
• Guardian Oracle interfaces
• SDKs
• demo applications
• developer documentation

The HumanAuthn and ZELF ID core architecture will remain proprietary while being exposed through developer SDKs with free-tier access for Base ecosystem developers.