Google Tests MPC Crypto Custody System as Key Security Risks Mount

How Google MPC Splits Control of Crypto Keys

Multi-party computation, or MPC, avoids keeping a complete private key in one location. Instead, cryptographic information needed to authorize a transaction is divided among separate participants or computing environments. The pieces work together when a transaction is signed, reducing dependence on any single machine or holder of a full private key.

Google said customers retain control of their key material and that the company cannot access it in unencrypted form, including when key shares are stored on Google infrastructure. The system combines MPC-based signing with transaction policies and key recovery rather than requiring institutions to assemble those functions independently.

A bank could, for example, distribute signing credentials across Google Cloud, its own hardware and another cloud provider. When a transaction is initiated, Google’s Confidential Space can run a policy engine before signing begins. Institutional rules could impose transfer limits, restrict destination wallets or require approval from several departments. Confidential Space uses hardware-isolated computing environments intended to protect sensitive information from unauthorized access.

Google said institutions can also select different signing thresholds. A transaction might require two of three participating signers or five of seven to jointly produce a valid signature. Credentials can be spread across an institution’s own systems, Google Cloud and competing cloud infrastructure, limiting reliance on a single provider for control of the assets. Google also said the service supports fast transaction signing and key recovery.

That architecture does not remove every custody risk. Transaction security still depends on how an institution configures its system, protects participants and controls access to approval policies. Legitimate users can also still be deceived into approving malicious transfers, even when the underlying signing credentials have not been directly compromised.

Private-Key Compromises Drive Billions in Crypto Losses

Private-key theft remains a significant source of cryptocurrency losses. An attacker who obtains the credentials controlling a wallet may be able to move its assets without the owner’s authorization, making key management central to institutional crypto custody.

The available figures show the scale of that exposure:

Chainalysis and DeFiLlama data place private-key compromises among the major drivers of crypto theft, while the Resolv and Humanity Protocol incidents show how compromised credentials can affect both directly held assets and wider project operations.

Google Positions MPC Against AI and Future Quantum Risks

Google is also presenting the service against a wider cybersecurity backdrop that includes artificial intelligence and, over the longer term, quantum computing. The current MPC system is focused on existing threats such as compromised credentials and unauthorized transactions rather than an AI system breaking the cryptographic signatures protecting major blockchains.

Chainalysis found that cryptocurrency scams linked to AI-tool vendors extracted an average of $3.2 million per operation in 2025, compared with $719,000 for scams without such links, or roughly 4.5 times as much. The findings suggested AI could be helping fraudsters operate at greater scale but did not establish that AI directly caused the higher proceeds.

Ethereum researcher Justin Drake has warned that advances in AI could eventually uncover mathematical shortcuts affecting the signatures protecting Bitcoin and Ethereum wallets, with a worst-case breakthrough potentially emerging within months rather than years. No AI system has demonstrated the ability to break those signatures.

Quantum computing presents a different, longer-term issue. Google researchers have estimated that a sufficiently powerful future quantum computer could theoretically derive a bitcoin private key from an exposed public key in roughly 9 minutes with advanced preparation. About 6.9 million bitcoin have been reported as potentially vulnerable to future quantum attacks because their public keys have already been exposed, although no existing quantum computer can perform such an attack.

Google said the MPC architecture is designed to support future post-quantum cryptography upgrades as blockchain networks adopt the required technology. At general availability, the service is designed to support conventional ECDSA and Ed25519 signing algorithms. Google said future cryptographic upgrades could be added without requiring institutions to redesign their systems or interrupt operations.