Google is unveiling Google Multi-Party Compute, a crypto custody system that splits transaction-signing keys across separate systems, at its first digital assets symposium in New York today, according to CoinDesk reporting.

The product is in private preview with several financial institutions, and Alphabet has already begun using it to secure its own assets, giving the platform an internal production reference ahead of its planned commercial availability in early 2027. Google has not disclosed pricing.

How the Split-Key Design Works

The system applies multi-party computation (MPC) to a signing key. The key is divided into fragments held by separate parties or machines, and a transaction requires a set number of fragments before it can be signed. The full key is never assembled in one place. Unlike on-chain multisignature, where approval rules are written into the blockchain itself, MPC enforces the threshold during signing, keeping both key fragments and approval logic off-chain — an approach that has become common across institutional custody platforms.

In practice, 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 approval thresholds such as two-of-three or five-of-seven. Before any signature is produced, 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.

Crypto's Security Problem

The pitch rests on a persistent industry weakness. Chainalysis attributed 43.8% of cryptocurrency stolen in 2024 to compromised private keys, while 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 a single developer's computer during the Humanity Protocol breach and drained wallets across two networks.

Such incidents illustrate 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, though the report links the two figures without proving that AI caused the difference. Ethereum researcher Justin Drake has warned that AI could eventually find mathematical shortcuts that weaken wallet signatures, but no AI system has demonstrated that capability. 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 have estimated that a sufficiently powerful future machine could derive a bitcoin private key from an exposed public key in about nine minutes, and roughly 6.9 million bitcoin have exposed public keys. Google says its architecture can adopt post-quantum signatures later without forcing institutions to rebuild their systems, though it has set no timetable. Background on how quantum machines threaten bitcoin explains which addresses are most exposed.

A Crowded Custody Market

Google enters a market led by Fireblocks, Fordefi, and BitGo. The company argued to CoinDesk that its banking relationships and security expertise give it an advantage, and it positions itself as a neutral supplier for banks that do not want to rely on competitors.

Banks already use specialized platforms, including BNP Paribas's custody work with Metaco and multi-institution vaults built with BitGo. Between the current preview and general availability, the undisclosed pricing, the composition of the early customer list, and the missing post-quantum timetable are the concrete markers to watch.

This article first appeared on Bitcoin Magazine and is written by Micah Zimmerman.