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Bonds

Bonds is a citizen-developed digital identity wallet prototype in Taiwan that explores how people can hold digital credentials and disclose only the information needed for a service. It uses privacy-preserving tools from the Ethereum ecosystem and checks issuer information recorded on Arbitrum One, an Ethereum layer 2 network.

Prototype testing privacy-preserving identity and offline verification

Digital identity · Taiwan

Institutional context

Identity verification can require people to disclose more personal information than a service needs, while also depending on centrally operated systems for continued access. For institutions, the challenge is to verify information reliably while supporting data minimization, privacy, and service continuity.

With support from the Ethereum Foundation’s Next Billion Fellowship, Mashbean started Bonds as a non-profit initiative in Taiwan. It explores whether a citizen-developed wallet can work with existing public identity infrastructure while giving people more control over their credentials. Bonds remains a working research prototype, not a released public service.

System design

Bonds allows people to hold digital credentials on their phones and share them with services that can verify the information. A digital credential is an electronic record of information about a person, with a digital signature that allows others to check who signed it and whether it has changed. The wallet can also store documents downloaded through MyData, a Taiwanese service for accessing personal records. Some credentials are digitally signed by the organization that issued them; others are created and signed by the person using the wallet. A person signing their own information is not the same as an institution confirming it.

The prototype also tests zero-knowledge proofs, which can show that a condition is met without revealing the underlying information. For example, a zero-knowledge proof can show that a recorded birth date meets an age requirement without revealing that date.

Bonds also tests credential verification without an internet connection. Devices prepare by downloading information about the organizations that issue credentials. They can then exchange and check information locally using a QR code and Bluetooth. They still rely on what was downloaded earlier and cannot see later changes until they reconnect.

Ethereum’s role

To check who issued a credential, Bonds compares information from Taiwan’s digital-wallet services with a public directory on Arbitrum One. The directory records information about organizations that issue credentials and whether their entries remain active, giving Bonds an additional public reference for verifying issuer information rather than relying solely on the digital-wallet service. Arbitrum One is an Ethereum layer 2 network that processes transactions separately while relying on Ethereum for security.

Bonds currently accesses these records through a service that provides blockchain data, rather than running its own infrastructure to verify the network directly. Its privacy-preserving proofs use tools from the Ethereum ecosystem, while personal credentials and proofs remain outside Ethereum.

Status and milestones

  1. 6 September 2026

    The developer reported three successful tests in which an iPad checked that information presented by an iPhone was accurate without either device connecting to the internet. The devices used verification information downloaded in advance and exchanged responses over Bluetooth.

  2. 5 September 2026

    The developer reported an age-threshold proof using a holder-signed credential derived from MyData. The test hid the birth date, but did not establish government certification of the person’s age.

  3. 2 September 2026

    The developer reported collecting a parcel at 7-ELEVEN using a Taiwan Mobile credential held in Bonds. A verification service issued the pickup QR code, which the store accepted. The report covered one credential and one successful handover.

  4. 13 November 2025

    The team published its lightpaper, outlining a citizen-held identity model, privacy goals, and a proposed approach to sharing trust information across institutions.

Implementation considerations

Institutions would need clear rules for which issuers and credential types they recognize for each service. A document stored on a device, or information signed by its holder, does not by itself establish that it was issued by a government agency or other trusted authority.

Services that work offline need rules for how long previously downloaded information can be trusted before it must be refreshed. They should also check whether repeated uses of a credential could be linked to the same person, even when some details are hidden. Before wider use, institutions would need to test whether the wallet works with their services, protects personal data, and offers accessible support and recovery if a phone is lost.

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