Allow retrieving sealed sectors with boost-http

[rjan90]

This is part of the Enabling clients to unseal data enhancement: https://github.com/filecoin-project/lotus/issues/10355.

Clients can't trust that what the SP has sent is data that contains the CID, so we can enable them to retrieve the whole piece, or with the retrieval specify what offsets of the sealed file the client wants. From the Boost side there we can potentially be an extension of http retrieval that allows clients to pull out the sealed data from the SP.

[LaurenSpiegel]

@willscott , with the new deal inclusion work, would it be possible to pull just a requested CID still sealed based on ranges (rather than the whole sealed piece)? is unsealing faster then since it is a smaller amount of data?

[willscott]

nope - doing partial unsealings at faster speed will take a change in the proof system, which is a larger effort that isn't part of the deal inclusion work

[LaurenSpiegel]

nope - doing partial unsealings at faster speed will take a change in the proof system, which is a larger effort that isn't part of the deal inclusion work

forget the faster part -- can you at least pull out the smaller portion of data?

[willscott]

@kubuxu is probably the authority here

[LaurenSpiegel]

Per Kubuxu, can transfer a subset of sealed bytes and have that portion unsealed but the compute will be about the same as if you unsealed the whole sector. Unsealing 32 bytes is roughly 90% of the work of unsealing all bytes

https://filecoinproject.slack.com/archives/C042H9KUQLD/p1677540000317949