While the blockchain can record the behavior of each wallet, it cannot determine whether ten wallets represent ten individuals or the same person.
This is not a problem in regular transfers, but when it comes to airdrops, reward claims, or community voting, it becomes a challenge: the rules state "one per person," but the smart contract can only recognize "one per address." By constantly changing wallets, the same person can potentially participate multiple times.
On the evening of July 28, the official Base developer account, Base Build, announced the launch of Base Verify Onchain. This feature aims to address the above challenge: applications can encode rules such as "each verified identity can participate only once" and "only users meeting specific conditions can participate" into smart contracts. Currently, Base Verify Onchain is running on the Base Sepolia testnet.
What is Base Verify Onchain?
In simple terms, Base Verify Onchain is a validation mechanism that links off-chain identity credentials with on-chain contract rules.
It does not allow smart contracts direct access to a user's X, Instagram, TikTok, or Coinbase account; instead, the off-chain service of Base Verify first determines if the user meets the requirements, issues a short-term valid verification result, and then the smart contract verifies this result on-chain to decide whether to allow the user to claim, deposit, mint, or vote.
The complete process can be divided into four steps.
The first step is for developers to predefine qualification rules in the smart contract, including a credential provider and one or more conditions. For example, the application may require the user to possess a verified X account, have a certain number of X followers, or hold a valid Coinbase One membership.
The second step is for the user to connect their wallet and sign a Sign-In with Ethereum (SIWE) message pointing to the application's contract. The application then sends the message and wallet signature to the Base Verify API.
In the third step, Base Verify's off-chain service first verifies the SIWE message signed by the user, recovers the signing wallet address from the signature, reads the provider and conditions specified in the message directed to the contract, and compares these conditions with the verified credentials stored in Base Verify for that wallet. Only when the user meets all conditions will Base Verify issue a short-term valid EIP-712 verification, returning the hash value (identityHash), expiration time, and verification signature to the application. Importantly, this hash value is used to identify and deduplicate the same verified identity through a one-way hash.
Finally, the application submits these three pieces of data to the smart contract. The contract checks if the signature is from a trusted signer, verifies if it has expired, and ensures that the validation matches the current chain, contract, and eligibility rules. Once the checks pass, the contract then queries whether the identityHash has been used before: if the same validated identity has participated before, even if a different wallet is used this time, the identityHash will be the same, leading the contract to reject the transaction.
It is essential to distinguish between two steps: whether the user meets the eligibility criteria, determined by the off-chain Base Verify service; and whether the signature is valid, expired, complies with the current contract rules, and if the identity has previously participated, which is verified on-chain by the contract. User's social account names, follower data, or membership information are not directly written on the blockchain as a result.
The identityHash is not a universal ID that can track users across all applications. It depends on both the validated identity and the application contract: if the same identity switches wallets within the same contract, the generated hash remains the same; however, the hash changes when entering a different contract. Therefore, different applications cannot directly link the same user solely based on the identityHash.
It Solves Eligibility Enforcement, Not a Universal Identity System
The core issue addressed by Base Verify Onchain is how to enable smart contracts to reliably enforce "who can participate" and "how many times the same identity can participate"?
It is suitable for on-chain scenarios with explicit rules, such as one-person-one-time airdrops, reward activities limited to specific users, and processes like voting, minting, depositing, or claiming where interference from multiple wallets needs to be reduced. The official testing page currently showcases two examples: users can validate and claim a test airdrop on Base Sepolia either as a "verified Coinbase One member" or an "authenticated X account holder."
It is important to note that Base Verify Onchain is not a universal identity system that proves a user's name, nationality, or other legal identities, nor is it a KYC procedure. A successful validation can only confirm that a verified identity meets the conditions preset by the contract. The contract neither learns the user's specific details nor should it infer the user's profile based on this validation.
Is a Base Airdrop on the Horizon?
Upon the announcement of Base Verify Onchain, it immediately sparks thoughts of Base tokens and a potential airdrop. If in the future there is a need to distribute on-chain rewards to real users, it indeed provides technical means to prevent duplicate wallet claims.
Meanwhile, Base has confirmed on BaseCamp in September 2025 that it is exploring the possibility of issuing a network token. However, the officials made it clear at the time that the work was still in the early stages of exploration, with no announced issuance timeline, token design, or governance arrangement.
Currently, Base Verify Onchain appears more like Base filling a gap in identity verification and anti-double-claim infrastructure, rather than initiating a countdown to an airdrop. In the future, if Base were to issue a network token and opt for distribution to users, this tool could indeed be used to screen eligible participants and prevent duplicate claims from the same identity.
Welcome to join the official BlockBeats community:
Telegram Subscription Group: https://t.me/theblockbeats
Telegram Discussion Group: https://t.me/BlockBeats_App
Official Twitter Account: https://twitter.com/BlockBeatsAsia
