What are they building on Celo?
Celo Verifiable Credentials Pilot for Phone Number Types
Spruce specializes in developing software for identity and data use cases in the blockchain space. Spruce worked with cLabs to develop a new feature, which is planned on being added to the Celo Attestation Service. Spruce's technology allows Attestation Service providers to check what type of phone number a user is using (e.g. mobile number, landline number, or VOIP number), and issue the user a verifiable credential attesting to that type of number. This feature partly addresses a general security threat on blockchains (called “sybil resistance”), which is being able to detect whether a user is unique or an alternative persona in order to avoid fraudulent activity (e.g. someone who created 100 phone numbers and 100 Celo accounts, to receive 100x the Celo rewards from Valora). This is useful because wallets including Valora might be more confident paying Celo rewards to a user, if they can verify that users are using a mobile phone number rather than a VOIP number (which can be purchased easily on the internet). By requiring non-voip mobile numbers for participation, it becomes harder to ‘game’ rewards services. In addition to this, this lays the groundwork to evolve the network with additional modules that bring standards-based claims to users to control their identity on Celo.