The Risks of Using Global FHE Key in Blockchain

**By Gurgen Arakelov** ([@g_arakelov](https://x.com/g_arakelov))

The Problem

Most FHE-based blockchain solutions use a single global encryption key. This approach has fundamental security and scalability issues that make it unsuitable for decentralized systems.

Why Global Keys Are Problematic

1. **Single Point of Failure**

If the global key is compromised, the entire system's privacy is broken

No way to recover from key exposure without restarting the entire network

2. **Centralization Risk**

Key management becomes a centralized bottleneck

Goes against the decentralized nature of blockchain

3. **Scalability Issues**

All participants need access to the same key

Key distribution becomes increasingly complex as the network grows

Threshold MPC Isn't Enough

While threshold Multi-Party Computation (MPC) can help distribute key generation, it doesn't solve the fundamental problems:

**Still a single key**: Even if generated distributively, it's still one key for everyone

**Key rotation complexity**: Changing the key requires coordination across all participants

**Performance overhead**: MPC operations add significant computational cost

Better Approaches

1. **User-Specific Keys**

Each user has their own encryption key

Users can encrypt data for specific recipients

No global key compromise possible

2. **Hybrid Approaches**

Combine FHE with other privacy techniques

Use FHE for specific computations, other methods for data sharing

3. **Keyless FHE**

Research into FHE schemes that don't require traditional key management

Still experimental but promising for blockchain applications

Conclusion

Global FHE keys are a security and scalability anti-pattern in blockchain systems. We need to move toward user-centric key management and hybrid privacy approaches that better align with decentralized principles.

The future of private computation in Web3 lies in solutions that provide strong privacy guarantees without sacrificing decentralization or creating single points of failure.

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*Read the original thread on [X/Twitter](https://x.com/FairMath/status/1943442903688212530)*