When it comes to decentralized storage, most people first think of transparency—data distributed across the entire network, verifiable by anyone. This is indeed its killer feature, but it also reveals a flaw: my medical records, business secrets, private photos—do I really want to leave these things in plain text on the public internet? That’s definitely asking for trouble. Because of this awkward situation, decentralized storage has long been regarded as a tool exclusively for public data, and privacy-sensitive scenarios still have to rely on centralized solutions.

However, Walrus’s introduced SEAL feature completely rewrites this situation. It doesn’t use the primitive method of encrypting data before upload, but instead employs a combination of encryption and smart contracts. Your data on Walrus remains encrypted, but who can access it, when they can access it, and under what conditions—all access permissions are legally defined by smart contracts on the Sui chain. Code is law, transparent and auditable.

On the technical level, SEAL uses identity-based encryption (IBE). It sounds academic, but it’s actually very clever. Traditional public key encryption requires obtaining the other party’s public key, which is a hassle in decentralized environments. But IBE is different—it allows any string to serve as a public key. A wallet address, an email, even a timestamp—all work. This flexibility makes permission control naturally straightforward.

Most impressively, SEAL performs encryption on the client side. Your data is encrypted from the moment it leaves your device. Even if all Walrus nodes are compromised, hackers will only get a bunch of unreadable gibberish. The decryption keys never leave the control of the smart contract on the Sui chain.