Attestation data contains latest crosslink, not just latest crosslink… #585
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… data The reason to do this is that it makes it calculable from inside an attestation how many epochs the attestation spans over, which is needed for proof of custody reasons. It's a relatively small change and so arguably easier to do now than to do as a patch in phase 1. Note that this changes the meaning of latest_crosslink.epoch, from the epoch when the latest crosslink was included to the epoch that the latest crosslink was for. This affects the line: * `state.latest_crosslinks[shard].epoch > state.validator_registry_update_epoch` for every shard number `shard` in `[(state.current_epoch_start_shard + i) % SHARD_COUNT for i in range(get_current_epoch_committee_count(state))]` (that is, for every shard in the current committees) But this may actually make it _more_ correct, as it means that in the case where >512 shards are processed per epoch, and so a committee from the previous epoch could get finalized in the current epoch, that would no longer count toward every shard having received a "new" crosslink.
djrtwo
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Feb 8, 2019
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… data
The reason to do this is that it makes it calculable from inside an attestation how many epochs the attestation spans over, which is needed for proof of custody reasons. It's a relatively small change and so arguably easier to do now than to do as a patch in phase 1.
Note that this changes the meaning of latest_crosslink.epoch, from the epoch when the latest crosslink was included to the epoch that the latest crosslink was for. This affects the line:
state.latest_crosslinks[shard].epoch > state.validator_registry_update_epochfor every shard numbershardin[(state.current_epoch_start_shard + i) % SHARD_COUNT for i in range(get_current_epoch_committee_count(state))](that is, for every shard in the current committees)But this may actually make it more correct, as it means that in the case where >512 shards are processed per epoch, and so a committee from the previous epoch could get finalized in the current epoch, that would no longer count toward every shard having received a "new" crosslink.