Project Introduction
LastKey is a decentralized dead-man switch for crypto inheritance built on the PortalDot V3 EVM. It allows crypto holders to securely pass on their digital assets to their loved ones without ever sharing their seed phrase. By utilizing Shamir’s Secret Sharing, automated heartbeat watchers, and soulbound NFT claim tickets, LastKey solves the critical problem of lost inheritance in self-custodial wallets.
Problem Solved
Every year, billions of dollars in cryptocurrency are lost forever because people pass away without sharing their wallet seed phrases. However, handing over a 12-24 word seed phrase while you are alive is incredibly risky—anyone with those words can instantly steal all your funds. Traditional legal wills do not work for self-custodial crypto wallets. LastKey removes this friction entirely, allowing users to set a “check-in” timer and distribute assets securely using a simple, memorable passphrase instead of a raw seed phrase.
Link
Demo Video: https://www.youtube.com/watch?v=-mLn3eUvj5Q
GitHub: GitHub - jaywon111/portaldot-hackathon-2026-lastkey-jaywon · GitHub
Pitch Deck: LastKey | PortalDot Hackathon 2026 - Google 幻灯片
Technical Highlights
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Shamir’s Secret Sharing (GF-256)
The biggest risk of a dead-man switch is the heirs not knowing the passphrase. We implemented Shamir’s Secret Sharing entirely in the browser and on-chain. The owner can split their passphrase into shards (e.g., 2-of-3). Heirs can combine their shards to unlock the vault, but no single heir can steal the funds alone. -
Automated Heartbeat (Off-chain Watcher)
If the blockchain sees the owner make any transaction (sending funds, buying an NFT), a GitHub Actions Watcher Bot detects it and automatically resets the inheritance timer by calling watcherCheckIn on the smart contract. -
Keeper Automation & Zero Centralized Custody
A hosted Node.js backend (deployed via Render) scans the owner’s wallet, checks ERC-20 token allowances, and sweeps approved tokens to the beneficiary. We do not hold centralized custody of user keys. The Keeper is an open-source script that beneficiaries run locally or on their own Render instance, ensuring a hacker breaking into our servers gains zero access to user funds. -
Soulbound Claim Tickets (ERC-721)
Beneficiaries receive non-transferable ERC-721 claim tickets minted directly to their wallets at setup. Transfers revert, preventing secondary market theft and proving their identity to the vault. -
Optimized for PortalDot pallet-revive
We aggressively optimized our complex contract down to 10.6 KB using viaIR and runs=1 to fit within PortalDot’s specific storage deposit limits, proving our deep integration with the PortalDot EVM environment. -
Real Transactions & Testnet Details
This is a fully functioning dApp with 261 passing Hardhat tests. The contract is live on the PortalDot V3 Testnet.
· Contract Address: 0x6BBE683abe51f6edF2D02b007ca722c7DF925FaC
· Deployer Address: 0xA0C42BF2406478C325a2636fF3A964976E9328B7
· Transaction Hash: 0x09a5943c932322634929f336e4d8e3ee6be3777ec9861e76a25e411c770e3521
· Block Number: 289073
· Network: PortalDot V3 Testnet (Chain ID: 420420777)
Team
LastKey — solo build by Jayisagod
· GitHub: @jaywon111
· Twitter/X: @jay1isagod
· Project nature: A single-person hackathon submission targeting the universal need for secure, private-key crypto inheritance.
Judges & Voting Fit
For Judges: LastKey features substantial, complex code (EVM compatibility, Shamir math, EIP-191 signatures) verified by 261 passing tests. It is deployed and fully functional on the PortalDot V3 testnet with verified on-chain proof (Tx Hash provided above). It addresses a universal human need and includes a realistic business model (per-claim fees).
For Community Voters: If you care about your family and hold crypto, LastKey is built for you. It removes the fear of losing your digital wealth forever. It’s a working, open-source tool that showcases the real-world utility of the PortalDot ecosystem.