#walrus $WAL

Encrypting storage is not just about locking files

Traditional file encryption is simple: encrypt with AES or RSA, then upload to a server. Download and decrypt when needed. However, this approach has a critical flaw: key management. Where is the key stored? If stored on your device, losing the device means losing the key. If stored in the cloud, it's no different from storing data in plaintext—service providers can access the key at any time. @walrusprotocol's Seal solution completely changes the game by moving key management onto the blockchain, using smart contracts to control who can decrypt data and under what conditions.

The core of Seal is threshold encryption. Data is encrypted with a single key, but this key is split into multiple shards and distributed across different nodes. To decrypt, a sufficient number of shards must be collected. For example, if there are 10 shards and the threshold is set to 6, any combination of 6 shards can reconstruct the complete key, but 5 or fewer cannot. This threshold mechanism ensures both security and fault tolerance—partial node outages or loss of key shards do not affect the overall system.

Key shard distribution is carefully designed—not just randomly sending shards to 10 nodes. Instead, it considers factors like node reputation, staking amount, and geographic distribution to ensure shards aren’t concentrated in a few entities. Shards are also rotated periodically. Even if one node is compromised, the stolen shards quickly become invalid. Attackers would need to simultaneously compromise multiple nodes within a short time window to obtain a valid key—something nearly impossible in practice.

Access policies controlled by smart contracts are Seal's killer feature. You can write a Move contract to define decryption conditions—such as only users holding a specific NFT being able to obtain key shards. The contract checks the user's wallet, verifies NFT ownership, and then requests sufficient nodes to release key shards. The entire process is verifiable on-chain, and no one can bypass the contract