Multi-Party Computation (MPC)

Overview

Multi-Party Computation (MPC) has become a standard approach for digital asset key management where teams need secure custody without single points of failure.

How MPC Works

Core Concept

MPC distributes key material across multiple parties:

1. Key generation creates shares without any party seeing the full key
2. Signing requires threshold cooperation (e.g., 2-of-3, 3-of-5)
3. No reconstruction - the full key is never assembled

Threshold Signatures (TSS)

The specific MPC application for digital assets:

• t-of-n schemes where t parties must cooperate to sign
• Share refresh to rotate key material without changing the public key
• Party replacement to change participants over time

Comparison with Alternatives

Implementation Architectures

Common Configurations

2-of-3 Institutional Setup:

• Institution holds 1 share
• Custody provider holds 1 share
• Cold backup holds 1 share

3-of-5 Enterprise Setup:

• Operations team holds 2 shares
• Security team holds 2 shares
• Executive backup holds 1 share

Vendor Landscape

Major MPC custody providers:

Operational Considerations

Policy Engine Integration

MPC solutions typically include:

• Approval workflows for transaction authorization
• Spending limits by time period or amount
• Address whitelisting for destination control
• Multi-level approvals based on transaction size

Disaster Recovery

Planning requirements:

1. Share backup procedures with geographic distribution
2. Recovery testing on regular schedules
3. Succession planning for key personnel
4. Insurance considerations for custody arrangements

Compliance Requirements

Regulatory expectations:

• Segregation of duties between share holders
• Access logging for audit trails
• Change management for policy updates
• Penetration testing of MPC infrastructure

Security Considerations

Attack Vectors

Known considerations:

• Collusion attacks if threshold parties coordinate
• Side-channel attacks during signing ceremonies
• Social engineering targeting share holders
• Implementation bugs in MPC protocols

Mitigation Strategies

Best practices:

• Independent custody of shares across organizations
• Hardware security for share storage
• Regular security audits of implementations
• Incident response procedures

Performance Characteristics

Latency Profiles

Typical signing times:

Throughput Considerations

For high-volume operations:

• Batch signing for efficiency
• Pre-computed shares for latency reduction
• Dedicated infrastructure for trading operations

Related Reading

• Architecture Pillar - Infrastructure context
• Firedancer - Related infrastructure