Author: Rusty Russell 2016-08-09 21:06:11
Published on: 2016-08-09T21:06:11+00:00
In an email exchange, Joseph Poon and Rusty Russell discuss the need for a "filter hint" that would prevent a large amount of outsourcing work. They agree on the necessity of such a hint but note that an HMAC check per registered commitment may not be fast enough. The two options presented are to use an index based on txid or to HMAC the transaction itself. The former option would require identifying when the transaction occurs as an index for outsourcing services, so the key can't be derived directly from the txid with a single HMAC/sha256. The latter option is preferred over the former since it has low computational cost and is constrained by block size. However, there is a risk of reintroducing malleability if the witness is included in the HMAC, while excluding it risks predictable transactions. To address this, Rusty suggests inserting randomness in the transaction (OP_RETURN? Different addresses each time?) or using the input signature from the witness as the filter.
Updated on: 2023-05-24T00:11:04.850281+00:00