Site data authentication

Walrus Sites offer a simple mechanism to authenticate the data that is served from the Walrus storage on the client side. Thus, Walrus Sites can guarantee (with various degrees of confidence, depending on the setup) that the site data is authentic and has not been tampered with by a malicious aggregator.

Authentication mechanism

The Walrus Sites resource object on Sui stores, alongside the resource information, a SHA-256 hash of the resource's content.

When the client requests a resource, the portal will check that the hash of the data received from the Walrus storage (and the Walrus aggregator in particular) matches the hash stored on Sui.

If the hashes do not match, the portal will return the following warning page:

Authentication Guarantees

Depending on the type of deployment, this technique gives increasing levels of confidence that the site data is authentic. We list them here in increasing order of assurance.

Remote server-side portal deployment

In this case, the user must fully trust the portal provider to authenticate the data. With a trusted portal, the authentication mechanism guarantees that the aggregator or cache (from which the blob has been fetched) did not tamper with the contents of the blob.

Remote service-worker portal deployment

Here, the portal provider is only trusted to provide the correct service worker code to the user. The user's browser will then perform the fetching and authentication. The guarantees are therefore the same as with the remote server-site portal, with the addition that the user can inspect the code returned by the portal provider and verify its integrity (e.g., by comparing it the hash of the service worker code to one that is known to be correct).

Local portal deployment

Finally, a user can clone the Walrus Sites repository and deploy a portal locally, browsing Walrus Sites through localhost. In this case, the user has full control over the portal code and can verify its operation. Therefore, they can fully authenticate that the data served by Walrus and Walrus Sites is what the original developer intended.