Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Updated get_custody_chunk_count #1099

Merged
merged 2 commits into from
May 20, 2019
Merged

Updated get_custody_chunk_count #1099

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
c14452b
Updated get_custody_chunk_count
vbuterin May 19, 2019
2018dd8
Update 1_custody-game.md
JustinDrake May 20, 2019
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
12 changes: 5 additions & 7 deletions specs/core/1_custody-game.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -254,12 +254,10 @@ The `empty` function accepts and SSZ type as input and returns an object of that
### `get_crosslink_chunk_count`

```python
def get_custody_chunk_count(attestation: Attestation) -> int:
crosslink_start_epoch = attestation.data.latest_crosslink.epoch
crosslink_end_epoch = slot_to_epoch(attestation.data.slot)
crosslink_crosslink_length = min(MAX_EPOCHS_PER_CROSSLINK, end_epoch - start_epoch)
def get_custody_chunk_count(crosslink: Crosslink) -> int:
crosslink_length = min(MAX_EPOCHS_PER_CROSSLINK, crosslink.end_epoch - crosslink.start_epoch)
chunks_per_epoch = 2 * BYTES_PER_SHARD_BLOCK * SLOTS_PER_EPOCH // BYTES_PER_CUSTODY_CHUNK
return crosslink_crosslink_length * chunks_per_epoch
return crosslink_length * chunks_per_epoch
```

### `get_custody_chunk_bit`
Expand Down Expand Up @@ -470,7 +468,7 @@ def process_chunk_challenge(state: BeaconState,
record.chunk_index != challenge.chunk_index
)
# Verify depth
depth = math.log2(next_power_of_two(get_custody_chunk_count(challenge.attestation)))
depth = math.log2(next_power_of_two(get_custody_chunk_count(challenge.attestation.data.crosslink)))
assert challenge.chunk_index < 2**depth
# Add new chunk challenge record
new_record = CustodyChunkChallengeRecord(
Expand Down Expand Up @@ -544,7 +542,7 @@ def process_bit_challenge(state: BeaconState,
)

# Verify the chunk count
chunk_count = get_custody_chunk_count(challenge.attestation)
chunk_count = get_custody_chunk_count(challenge.attestation.data.crosslink)
assert verify_bitfield(challenge.chunk_bits, chunk_count)
# Verify the first bit of the hash of the chunk bits does not equal the custody bit
custody_bit = get_bitfield_bit(attestation.custody_bitfield, attesters.index(responder_index))
Expand Down