Google Cloud on Wednesday introduced a new option for banks considering crypto custody: Google Multi-Party Compute, a key-signing service the company presented at what it described as its first event dedicated to digital assets.
The pitch is straightforward. A bank can split control of a private key across several environments so that no single provider, including Google, holds the full key. Google said one share could sit on the bank’s own hardware, another in Google Cloud, and a third with a competing cloud provider. The company also said it cannot read customers’ key shares in plaintext, including the shares stored on its own servers.
The service is in private preview. Google’s documentation describes it as a platform that combines threshold signing with transaction policies and governance controls.
Rich Widmann, director of digital assets strategy at Google Cloud, said, “Digital asset adoption and tokenization are at an inflection point. As regulated financial institutions begin adopting blockchains and tokenization, they need scalable, proven infrastructure to secure their clients’ assets.”
Release notes for the product show preview updates going back to August. Google said unnamed banks and other early partners are testing the service, and that its parent company, Alphabet, has started using it for its own Ethereum and Solana holdings. General availability is targeted for early 2027. Google did not provide pricing.
No full key in one place
According to Google’s documentation, each key share is created and stored by a separate party on its own secure hardware. Those parties then cooperate to sign transactions without ever assembling the full key in one place.
The documents say that if an attacker compromises fewer parties than the signing threshold, that attacker cannot forge a signature or reconstruct the key. Customers choose the threshold themselves. Google gave 2-of-3 and 5-of-7 as examples.
Google also outlined a policy engine that runs in its Confidential Space environment. That engine checks each transaction against rules such as spending caps and approved destinations.
Still, the documentation says the result is advisory rather than binding. It guides signers, but it does not make the final decision. If enough signers agree, they can override a denial and push a transaction through.
Competing in the institutional custody market
That puts Google into competition with BitGo, Fordefi, and Fireblocks, which already sell institutions tools to secure and approve blockchain transactions.
The report also noted that the head of embedded wallets at Fireblocks co-founded Dynamic. Fireblocks has argued that many people already use a crypto wallet without realizing it.
Google highlights AI and quantum risk, but the listed threats are more familiar
Google is framing the service around AI and quantum risk, but the threats listed in its documentation are more conventional: stolen or misused keys, outages, and lost key material.
The company said the system can be upgraded to post-quantum signing as blockchains adopt quantum-resistant cryptography, though it did not say when that would happen.
Coinbase has urged Bitcoin developers to make sure a quantum-resistant upgrade works for large custodians.
Google said the service will support ECDSA, which is used by Bitcoin and Ethereum, and Ed25519, which is used by Solana, when it reaches general availability. At the same time, the overview page still labels Solana as “coming soon,” while an Oct. 1 release note added distributed signing that uses Ed25519’s standard challenge hashing.