Decentralized 'Forgot my password', to onboard the next billion users
First note on the demo: my macbook didn't like recording whilst doing ZK work. I used an earlier demo video not specific to this hackathon.
Nihilium
Nihilium is a novel, context-agnostic cryptographic primitive that solves one of crypto’s most persistent problems: losing access to your keys.
Unlike existing approaches such as social recovery, MPC, or account abstraction recovery, Nihilium operates directly on the keys themselves in an off-chain manner. It enables developer to define flexible, composable recovery conditions (timelocks, zk email proofs, zk identity proocs, multi-party thresholds, or anything else expressed as a smart contract in any combination) while maintaining fully self-custodial.
A core element of Nihilium is auditable access attempts, every recovery attempt is observable and verifiable. This creates a new layer of trust and accountability that current recovery methods lack.
Because it is key-native and context-agnostic, Nihilium can be integrated into virtually any existing system, traditional EOAs,, multisig setups, embedded wallets, Bitcoin, or non-EVM chains, privacy tooling and encrypted data, all without requiring users to migrate to smart accounts or change their current key management workflow.
Key features:
Directly on the keys: No smart contract wrappers or on-chain migration required
Off-chain by design: Fast, gasless setup and execution of recovery logic
Auditable recovery attempts: Transparent and verifiable access logs
Composable conditions: Build complex, customizable recovery policies
Fully context-agnostic: Works across wallets, chains, and applications
Potential Impact
Nihilium can dramatically reduce onboarding friction and user drop-off in crypto wallets while opening the door to more secure and user-friendly experiences in decentralized social platforms, identity, privacy-focused applications, DAO treasury management and opens up applications previously only available for power users.
By turning key recovery from a fragile, all-or-nothing process into a programmable, auditable, and flexible primitive, Nihilium aims to make self-custody safe and accessible for the next wave of users.
Why on Arbitrum?
Nihilium is setup as an application level optimistic setup with provable mishaviour as slashing mechanism. This means for normal operation a user never interacts with the chain and makes it technically capable to scale massively.
However, there is a single element that requires an on-chain transaction, that is a single transaction per block/epoch for the entire protocol. Having this cheap and fast (not 10 seconds) allows for a 'snappier' experience.
Links:
https://linktr.ee/nihiliumio
Core contracts: https://github.com/nihilium/nihilium-core/tree/main/packages/core/contracts
Arbitrum deployment + testing on Arbitrum One during hackathon: https://arbiscan.io/txs?a=0xd08dee75dc7ebb76a69c15a3f77af42975655534&p=10
Product Canvas: https://docs.google.com/presentation/d/12P4hQhBSEaWCiIlGugsw3JllLLKU-lTTTigTlFgIvFc/edit?usp=sharing
GMT Canvas link: https://docs.google.com/presentation/d/1psL41cOSL4gdcDZXyfI6Dc-hGQi9v6XpKSajQx3vCMU/edit?usp=sharing
Demo link: https://recovery.nihilium.io
It was a nice chance from normal hackathons to mostly focus on product, positioning and GTM. Although Nihilium was maybe not the directly targeted project I got good feedback and learned a lot. There is still much to do
Unfunded, not actively raising, but always welcome introductions with parties that might be intereseted
