Google Unveils MPC Crypto Custody System Aimed at Banks

Google is unveiling a bank-grade crypto custody system that splits signing keys across separate machines, at its first digital assets symposium in New York, according to CoinDesk. The product, called Google Multi-Party Compute, is already in private preview with several financial institutions, and Alphabet has started using it to secure its own assets. Google plans commercial availability in early 2027 and has not disclosed pricing.

The system applies multi-party computation to a signing key. The key is divided into fragments held by separate parties or machines, and a transaction requires a set number of those fragments to sign. The full key is never assembled in one place.

How does the split-key architecture work?

A bank could hold one share on its own hardware, another in Google Cloud, and a third with a rival cloud provider. Institutions can set thresholds such as two-of-three or five-of-seven. Before any signature goes out, a policy engine running inside Google's Confidential Space checks the transfer against limits, destination restrictions and approval rules.

Google says it has no access to key shares in unencrypted form, per CoinDesk. That claim matters for banks weighing whether a third party could ever reconstruct custody controls — the core question regulators ask of any custodian.

Why is Google targeting key compromise?

The pitch rests on a persistent, measurable problem. Chainalysis attributed 43.8% of cryptocurrency stolen in 2024 to compromised private keys. DeFiLlama data shows roughly 40% of the $16.69 billion lost to hacks through June came from key compromises. In June, an attacker took seven keys from one developer's computer during the Humanity Protocol breach and drained wallets across two networks.

Those incidents show how concentrated signing authority creates a single point of failure. The industry has responded by recommending multi-vendor multisignature setups that spread control across hardware and software providers.

Google also frames the product against AI-enabled fraud. Chainalysis found that scams linked to AI tool vendors averaged $3.2 million per operation in 2025, compared with $719,000 for other scams. The report links the two figures but does not prove that AI caused the difference.

What about quantum risk?

Ethereum researcher Justin Drake has warned that AI could eventually find mathematical shortcuts that weaken wallet signatures. No AI system has shown that capability, and Google's MPC design targets stolen credentials and unauthorized transfers, not a break in the underlying cryptography.

Quantum computing presents a separate, longer-term risk. Google researchers estimated that a sufficiently powerful future machine could derive a bitcoin private key from an exposed public key in about nine minutes. Roughly 6.9 million bitcoin sit at addresses with exposed public keys. Google says its architecture can adopt post-quantum signatures later without forcing institutions to rebuild their systems, but it has set no timetable.

Can Google compete with Fireblocks and BitGo?

Google enters a market led by Fireblocks, Fordefi and BitGo. Google argued to CoinDesk that its banking relationships and security expertise give it an advantage. It also positions itself as a neutral supplier for banks that do not want to depend on competitors — a direct play for institutions uneasy about custody vendors that also run their own wallet businesses.

Banks already use specialized platforms, such as BNP Paribas's custody work with Metaco and multi-institution vaults built with BitGo. Google's differentiator is distribution: it already sells cloud infrastructure to the same compliance and security teams that would evaluate a custody layer.

The commercial test arrives in early 2027, when pricing, audit sign-off and the first production deployments will show whether banks trust a cloud giant with the architecture of their key management.