Blockchain Platform achieved 100% Ethereum Compatibility with Secure Multi-Party Computation

Project Overview

The client operates blockchain-based wallet infrastructure used to manage organizational digital asset transactions. As transaction volume and security requirements grew, the platform’s existing custodial wallet model, built around a single centralized private key, no longer matched the risk profile the business needed to support. The team required an MPC Wallet Architecture that could distribute signing authority across independent parties while preserving compatibility with existing Ethereum-based transactions and integrations.

• 100% Custodial Ownership
• Single Complete Private Key
• 0% Key-Share Division

The Challenge

The previous custodial architecture concentrated private-key management and transaction signing within a single centralized security boundary. This created a high-value target, meaning a compromise of that boundary could expose full signing capability and demanded a stronger approach to distributed key management going forward.

• Single point of compromise: The complete private key existed as one secret within a centralized boundary, meaning a single successful compromise could expose full signing capability for every wallet transaction.
• Unchecked signing authority: One component held full authority to sign transactions independently, with no requirement for a second party to validate or approve a signing request before broadcast.
• Cryptographic material co-located with application infrastructure: Sensitive key material was not isolated from general application logic, increasing the potential blast radius of any infrastructure-level vulnerability or breach.
• Limited authorization and audit depth: The prior model lacked layered authorization checks and structured audit logging, making policy-driven approval difficult to enforce before sensitive signing operations occurred.
• Compatibility constraints on any new design: Any replacement architecture needed to preserve full compatibility with existing Ethereum-based transactions and signatures, ruling out approaches that would break downstream integrations.

The Solution

The engineering team designed the replacement around secure multi-party computation, selecting a two-party ECDSA protocol so signing authority could be split between independent parties without requiring the complete private key to exist anywhere in the system:

• Two-party ECDSA signing protocol: Adopted a Lindell-based two-party ECDSA implementation as the core of the Multi-Party Computation Wallet, ensuring the complete private key is never reconstructed or stored as a single secret.
• Hardware-isolated key shares: Deployed AWS Nitro Enclaves to isolate key shares and cryptographic operations from general application infrastructure, using VSock for minimal-surface, controlled communication between enclaves.
• Clear language-level separation of concerns: Used Rust for networking, orchestration, authorization, validation, and secure memory management, while isolating C++ strictly to deterministic MPC cryptographic computation for a smaller trusted surface.
• Proven cryptographic foundation: Selected Coinbase’s cb-mpc library to run the Multi-Party Computation Wallet’s threshold ECDSA operations, relying on Paillier encryption and zero-knowledge proofs for verifiable protocol correctness.
• Layered authorization and audit controls: Added cryptographic admin authorization and TOTP authentication as prerequisites for signing, reinforcing distributed key management with sealed storage, zeroization, and structured audit logging.
• Independent, verifiable key generation: Structured wallet creation so each party generates its own key share independently, exchanging only public information to derive the shared public key and Ethereum address.

The Results

The new MPC Wallet Architecture delivered clear structural and security improvements over the previous custodial model:

• 2 independent parties now required to jointly authorize every signing operation
• 0 instances of the complete private key being reconstructed or stored as a single secret
• 7 layered security controls implemented, from enclave isolation to structured audit logging
• 100% compatibility maintained with existing Ethereum-based transactions and signature formats
• 6 structural improvements delivered over the prior custodial model, per the architecture’s own comparison
• 1 hardware-isolated enclave boundary now protects all key-share material and cryptographic operations

Key Takeaway

This migration shows that secure multi-party computation can remove a single point of compromise without sacrificing existing transaction compatibility. By distributing signing authority across independent, hardware-isolated parties, the architecture creates a stronger, more auditable foundation that can extend to additional signing policies and multi-chain support as the platform scales.