Google is testing a crypto custody service for banks. What MPC is, and what it means for your own wallet

Google is building a way for banks to hold crypto without keeping a whole private key anywhere. Its cloud division showed the service, called Multi-party Compute, to financial firms in New York on October 28, 2026. It's still a test product for institutions, but the idea behind it is worth understanding, because it's the same problem every crypto owner faces: whoever holds the key controls the coins.

What happened

CoinDesk reported that Google would present the service on Wednesday, October 28, at the first digital assets symposium it has hosted, in New York City. Google told CoinDesk the product is in private preview and isn't generally available yet, and that a group of early partners and big financial firms are trying it out. It didn't name those institutions. According to Cointelegraph, the event's speakers included people from Morgan Stanley, OKX, Citi and Wells Fargo.

Google's own documentation describes Multi-party Compute as a Google Cloud custody platform for the keys that sign digital asset transactions. Its release notes go back to August 2026, and an October 1 update expanded its Bitcoin rules to cover things like spending amounts, change outputs and address types.

The timeline, per the two outlets:

• Now: private preview. Cointelegraph notes that Google offers preview products "as is," with possibly limited support.
• Early 2027: the target for general availability, a Google Cloud spokesperson told Cointelegraph. CoinDesk reported the same timing and said pricing hasn't been disclosed.
• Google's own use: CoinDesk reported that Alphabet, Google's parent company, has started using it to protect digital assets the company holds on Solana and Ethereum. Google didn't say which assets.

What MPC is, in plain English

A normal crypto wallet has one private key, usually backed up as a seed phrase. If a thief copies that one secret, the coins are gone. MPC, short for multi-party computation, avoids having that one secret at all.

• Control is spread across shares. Separate parties each generate and keep their own share, so a complete key is never created in the first place. Google's documentation says they sign together without ever building or storing the full private key.
• A minimum number must agree. The customer sets how many shares are needed to sign, for example any 2 of 3 people on a treasury team. Google's documentation says a thief who breaks into fewer than that number can't sign or rebuild the key, and signing can carry on when some parties are offline, as long as enough remain to meet the required number.
• The shares can live in different places. The options Google lists are its cloud, the customer's own premises, or users' mobile devices. CoinDesk reported that Google says customers keep control of their key material, and that Google can't read it in unencrypted form even when shares sit on its servers.
• Rules run before signing. Firms can write policies such as spending limits or lists of approved destinations. Google's documentation is clear that these rules advise rather than block: if enough signers approve, a transaction the rules flagged can still go through.

In the preview, Google's overview page lists the signature type used by Bitcoin, Ethereum and Ethereum-compatible networks, and labels Solana-style keys "coming soon." Google told CoinDesk it plans to support both signature types once the service is generally available. Its Bitcoin page also notes that, in this design, an institution doesn't need a human-readable seed phrase at all.

MPC isn't the same as multisig. Multisig uses several separate keys, and the blockchain itself checks that enough of them signed. MPC turns shares of one key into a single, ordinary-looking signature, so the network can't tell that several parties were involved.

Why big firms care

Stolen keys are one of crypto's biggest sources of loss. CoinDesk cites Chainalysis data that compromised private keys made up 43.8% of crypto stolen in 2024. Google told CoinDesk it hasn't offered a dedicated MPC custody product for crypto before. Its Bitcoin custody guide contrasts the new service with Cloud KMS and Cloud HSM, where a complete signing key sits inside a single hardware module.

MPC itself isn't new to crypto, CoinDesk notes, and Google published guidance on building MPC systems on its cloud back in 2023. What's new is a company of Google's size offering it as a ready-made service, at a time when banks are starting to hold crypto and tokenized assets for clients. That ties into the rules regulators are writing now, such as the SEC's crypto custody proposal for advisers and funds.

What it means for you

• You can't sign up for it. It's an institutional cloud service in private preview, not an app. Nothing changes for your own wallet or exchange account.
• Your seed phrase is still the whole game. Most personal wallets still rely on one seed phrase. Keep it offline, never type it into a website, and never share it. Our seed phrase guide covers how.
• Splitting keys doesn't stop trickery. As CoinDesk points out, the pre-signing checks may lower the risk of unauthorized transactions, but a legitimate signer can still be fooled into approving a bad one. The same is true for you: always check what a transaction does before you approve it.
• If an exchange or bank holds your crypto, its custody setup matters to you. Ask how it protects keys, and read our wallets guide for the trade-offs between holding coins yourself and letting a company do it.

The takeaway

Google is testing a service that lets institutions approve crypto transactions together without any one machine or person holding a full key, with a launch target of early 2027. For everyday holders it's a useful lesson rather than a product: the key is everything, so protect yours. This is education, not financial advice, and it reflects Google's documentation and reporting by CoinDesk and Cointelegraph as of October 29, 2026.

Published October 29, 2026 by Dave McNaught. Educational content, not financial, legal or tax advice. Spot an error? Request a correction.

About the author

Dave McNaught

Dave McNaught has worked in IT since 1999 and founded All Business Technologies (ABT) in 2003, a Boston-area firm providing Managed IT, Cybersecurity, Managed AI, Web Design and App Development. He publishes The Crypto Guide.

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