Google Previews Key-Splitting Crypto Custody Tool For Banks

Google is reportedly unveiling Google Multi-Party Compute, a crypto custody system that splits signing keys across separate systems, at its first digital assets symposium in New York today. The product is in private preview with several financial institutions. Alphabet has started using it to secure its own assets, according to CoinDesk reporting.

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 fragments to sign. 

The full key is never assembled in one place. 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, 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 issues

The pitch rests on a persistent 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. 

Such 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. 

Ethereum researcher Justin Drake has warned that AI could eventually find mathematical shortcuts that weaken wallet signatures. No AI system has shown 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 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 have 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. Background on how quantum machines threaten bitcoin explains which addresses are most exposed.

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 rely on competitors. 

Banks already use specialized platforms, such as BNP Paribas’s custody work with Metaco, and multi-institution vaults built with BitGo.