Multi-Party Computation (MPC)

Overview

Multi-Party Computation (MPC) has become the dominant approach for institutional digital asset key management, enabling 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