The: Daniel ⚡️ on Nostr: This is outstanding! Thanks to ericfj for bringing this to my attention. One of the ...

This is outstanding! Thanks to ericfj (npub10xv…g437) for bringing this to my attention. One of the biggest concerns I hear from both new and veteran users is the risk of keys being lost or compromised, and the lack of key delegation that is essential to running a business account.

Do we want to #grownostr the right way? We need to solve key management. I can’t think of a higher priority.

quoting note1ura…atlc

Like King Arthur pulling the sword Excalibur from the stone to reclaim his rightful place as king, the Excalibur system empowers Nostr users to recover control of their digital identities and networks from malicious infiltrators. This proposal introduces a robust framework for key recovery and re-association, ensuring that users can seamlessly regain control of their accounts while preserving their social connections, metadata, and event history. In an age where security and trust are paramount, Excalibur offers a practical and resilient solution to one of the most pressing challenges in decentralized networks.

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# The Importance of Key Recovery on Nostr

One of Nostr’s greatest strengths is its reliance on public and private key pairs to establish identities and ensure message authenticity. However, the simplicity of this cryptographic model comes with a significant vulnerability: key compromise. If a user’s private key is lost or stolen, they face catastrophic consequences:
* Loss of Identity: The user cannot post, interact, or manage their profile.
* Disruption of Social Graph: Followers and contacts lose their connection to the user.
* Trust Erosion: An attacker controlling the compromised key can impersonate the user, damaging their reputation.

While decentralization is a core principle of Nostr, the lack of a built-in recovery mechanism undermines long-term usability and user confidence. Excalibur addresses this gap with an innovative system for recovering compromised keys and maintaining social continuity.

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# Proposed Solution: The Excalibur System

The Excalibur system introduces a primary key and secure backup key model to Nostr, enabling users to recover their accounts and re-associate events in the event of key compromise. This system relies on a combination of cryptographic proofs, event indexing, and client/relay cooperation to ensure a seamless and secure transition.

## 1. Primary and Secure Keys

Users establish a primary key for everyday activity and a secure backup key stored offline.
The primary key broadcasts an association with the secure key using a ```set_secure_key``` event.

## 2. Key Transition Event

Upon detecting a compromise, the user activates the secure key by publishing a ```key_transition``` event.

This event includes:
* The compromised primary key.
* The new secure key.
* A cryptographic proof linking the two.
* A timestamp and optional metadata.

## 3. Social Graph Transition

Clients automatically replace the compromised key with the secure key in follow lists, contact lists, and other social data.

Followers are notified of the transition and encouraged to follow the secure key.

## 4. Unified Identity View

Historical events remain immutable but are re-indexed by relays to associate with the secure key for continuity.

Clients display a unified profile view, differentiating old and new events.

## 5. Seamless Transition for Existing Accounts

Existing Nostr users can integrate Excalibur by broadcasting a set_secure_key event linking their current primary key to a secure backup key.
While historical events and metadata associated with the primary key remain unchanged, all new events after activation of the secure key are seamlessly associated with the updated identity.
Clients should provide user-friendly tools to guide existing users through this setup process.

## 6. Endless Security Chain

Once a secure key is activated and becomes the new primary key, users must set up a new secure backup key immediately by broadcasting a new ```set_secure_key``` event.

This ensures an endless chain of security, preventing future compromises from leaving users vulnerable.

Clients should include UX enhancements such as prompts, reminders, and automated tools to help users maintain their security chain efficiently.

## 7. Insurance Model for Relays

Users pay an upfront premium to relays for re-association services, ensuring resources are available for recovery operations.

Clients act as brokers, aggregating multiple relay insurance contracts into a single, user-friendly offering. They manage user payments, distribute premiums to participating relays, and earn a commission for their services.

This brokerage model incentivizes clients to participate actively in the Excalibur system and ensures broader adoption across the network.

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# Implementation Framework

## Cryptographic Foundations

- The secure key must be pre-announced and linked to the primary key using a signed ```set_secure_key``` event.
- During key transition, the key_transition event includes a signature proving the association.

## Relay Behavior

- Relays index the key_transition event and re-link historical data to the secure key.
- Events from the old key are tagged as "deprecated" but remain accessible.

## Client Behavior

- Clients validate the ```key_transition``` event and update social graphs automatically.
- Followers are notified and prompted to follow the secure key.
- Profiles display both old and new events under a unified identity.
- Clients implement features to facilitate existing users' onboarding and provide tools to manage the security chain seamlessly.

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# Benefits of Excalibur

**Resilience**: Users can recover from key compromise without losing their digital identity or network.

**Trust**: The cryptographic proofs ensure the legitimacy of key transitions, preserving trust in the system.

**Sustainability**: The insurance premium model incentivizes relay adoption and ensures fair resource allocation.

**User-Friendly**: Automated transitions reduce the complexity for end users, making Nostr more accessible.

**Adaptability**: Existing accounts can benefit from Excalibur without disruption, ensuring broad applicability.

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Call to Action

The Excalibur system is a vital enhancement to the Nostr protocol, addressing the critical issue of key recovery while maintaining decentralization and user sovereignty. By adopting Excalibur, we can strengthen the network’s resilience, foster trust, and ensure that users retain control of their identities in an ever-evolving digital landscape. We invite the Nostr community to collaborate on refining and implementing this proposal, turning the vision of Excalibur into a reality.

Together, let’s ensure that no user is ever left powerless in the face of compromise. Let’s reclaim the sword and secure the kingdom.