Google Wallet integrates ZK-proofs, a tech incubated by crypto industry

Google is integrating zero-knowledge proofs into its wallet as an identity solution, according to a recent announcement. The digital ID will initially roll out in the UK, but will soon be introduced in the United States and other countries.

"Given many sites and services require age verification, we wanted to develop a system that not only verifies age, but does it in a way that protects your privacy," Google wrote in a blog on Tuesday. "That's why we are integrating Zero Knowledge Proof (ZKP) technology into Google Wallet, further ensuring there is no way to link the age back to your identity." 

It’s unclear to what degree Google's ZKs will touch to crypto; however, they will be made open-source for other wallets and online services. The company notes Google Wallet has implemented a custom-designed ZK system using tech from Ligero, a startup launched in 2018 to build data privacy platforms backed by major crypto movers including Galaxy Ventures, 1kx, Franklin Templeton, Robot Ventures and Digital Currency Group.

Zero-knowledge proofs were largely of academic interest to cryptographers and computer scientists before finding practical applications in the crypto industry. Projects like Zcash contributed serious innovations to the tech, which is now being implemented in and out of crypto for anything from scalability to privacy.

Introduced in the 1980s by Shafi Goldwasser, Silvio Micali, and Charles Rackoff, zero-knowledge proofs are used to prove statements without revealing any underlying information. The classic example is proving to a bartender that someone is of drinking age without revealing their actual age. 

For years, the ZK field was hampered by the computational complexity involved in implementing it. Crypto developers continue finding solutions to hard cryptographic problems, like scalability. 

Ethereum and other blockchains use zk-Rollups — like StarkNet and zkSync — to batch transactions off-chain, reducing costs and congestion. Additionally, zk-SNARKs and zk-STARKs are used to shield transaction details for privacy. Newer ZK variants like Plonk and Marlin are also being used for data storage, like in projects including Filecoin. 

According to the announcement, Google Wallet will have consumer applications on and off-line, including as a U.S. passport for domestic flights. “New use cases are on the way in collaboration with our strong partner ecosystem. Soon, you'll be able to use your digital ID to recover Amazon accounts, access online health services with CVS and MyChart by Epic, verify profiles on platforms like Uber and more,” Google wrote. 

Micali is the co-founder of Algorand, which Goldwasser advises. 

Editor's note (May 2, 2025): Updates to note the ZKs incorporate custom version of Ligero's tech.