By default, all files (or blobs) stored in Walrus are public and discoverable. If you're looking to keep your data private, you'll need to take additional steps such as encrypting your data before uploading it to Walrus. To secure your data, consider using encryption. An application like Seal can be utilized for encryption and onchain access control. Seal integrates with Walrus to encrypt data and define access policies.

For your specific privacy needs, you might use an application like Tusky that encrypts your data or look into similar tools before uploading to Walrus.