I'm thinking of a scheme where B gets paid to store a file* F for A until at least a time T.
For this to work, I'm thinking that it is needed for incentives for B to..
1) actually store the file until time T.
2) transfer the file to A on request.
I have a sketch for this, but my question is whether it is possible to remove the trusted third person from the scheme?
For 1), I'm thinking that a secret random nonce N is generated by a third party, C, and V=HASH(N+F) is calculated by C**. At time T, C reveals N to the world, and B can prove that he kept the deal to C by calculating V.
I haven't though through 2) yet, but I'm thinking it can be possible for A to initiate some kind of escrowed buy of F from B.
I hope this forum is the right place do discuss this or similar schemes.
*) Or rather, a forward erasure coded encrypted N-of-M chunk of a file.
**) This is an unfortunate significant overhead, as F must now be transferred from A to C.