Can someone explain sector sealing?

I don’t understand what goes on during “sector sealing.” The most detailed explanation I can find is in the spec, § 2.6.2 (requires local copy), which basically explains the sealing process as assembling the raw data that is to be stored into a Merkle tree and generating a proof. Proof of what? Knowledge of the tree root hash?

Also, the uppercase term SEAL is sometimes used. Is SEAL an abbreviation for something?

Thank you.

Hi @filet,

The sealing process creates a unique encoding of the data, called a replica, that is used in Proof of Replication. Proof of Replication and Proof of Spacetime (election-based) are the 2 core proofs of storage used in Filecoin. They are used to verify that a unique replica of a data CID exists in physical storage in the world, continuously over time. SEAL is not an abbreviation afaik, different people have contributed to the Spec.

The code for the proofs can be found here: and is likely to be more up to date than the current Spec. is a blog post / podcast that talks about these proofs as well.

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