When it comes to file encryption, most people's first reaction is to encrypt with AES or RSA and then upload to a server. It sounds reassuring, but the real critical issues quickly emerge.

Where to store the keys? This is truly a headache of a multiple-choice question. Store locally? If the device is lost, the key is gone too. Store in the cloud? That’s equivalent to turning ciphertext into plaintext; the service provider can access the key at any time. In my opinion, this traditional approach is essentially just closing your eyes and plugging your ears.

Let's look at how Walrus's Seal solution works. They move key management onto the blockchain, using smart contracts to determine who can decrypt under what conditions. This approach truly changes the game.

Seal's core technology is called threshold encryption. Simply put, your data is encrypted with a key, but this key is split into multiple shards, scattered across different nodes. To decrypt? You need to collect enough shards. For example, with 10 shards and a threshold of 6, any 6 shards can reconstruct the full key, but 5 cannot. This ensures security while providing fault tolerance—if some nodes go offline or shards are lost, the system still functions smoothly.

The distribution of shards is also carefully considered; it’s not just randomly sending them to 10 nodes. The system evaluates factors like node reputation, staking amount, and geographic distribution to ensure shards are not concentrated in a few entities. Moreover, these shards are periodically rotated, so even if a node is compromised, the shards obtained will quickly become invalid. Attackers would need to compromise multiple nodes simultaneously within a short time frame to obtain a valid key—which is practically impossible in real-world scenarios.

The smartest part is the access control via smart contracts. You can set flexible access rules based on your needs, such as only specific addresses being able to decrypt within a certain time window, or requiring multiple authorized parties to approve access. This is true data sovereignty.