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Fixes a few bugs with deposit verification. #388

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merged 9 commits into from
Jan 10, 2019
Merged

Fixes a few bugs with deposit verification. #388

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5f19622
Add clarifying comment about where this index is coming from
ralexstokes Jan 3, 2019
dff84c0
Fixes bugs with description of deposit verification.
ralexstokes Jan 3, 2019
4ea4302
Update 0_beacon-chain.md
JustinDrake Jan 4, 2019
6f5a865
Reorder type so the ssz serialization matches other uses
ralexstokes Jan 9, 2019
c5de2fe
Add missing deposit root when performing Merkle verification
ralexstokes Jan 9, 2019
f49f7ed
Use the correct name for the `amount` field
ralexstokes Jan 9, 2019
7a6854a
Fix variable name that was lost in botched rebase
ralexstokes Jan 9, 2019
d628346
Broadcast `merkle_tree_index` in lieu of the deposit count
ralexstokes Jan 9, 2019
4cf06d9
Truncate the index into the Merkle tree to bytes[8]
ralexstokes Jan 9, 2019
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24 changes: 13 additions & 11 deletions specs/core/0_beacon-chain.md
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Original file line number Diff line number Diff line change
Expand Up @@ -355,11 +355,11 @@ Unless otherwise indicated, code appearing in `this style` is to be interpreted

```python
{
# Receipt Merkle branch
'merkle_branch': '[hash32]',
# Merkle tree index
'merkle_tree_index': 'uint64',
# Deposit data
# Branch in the deposit tree
'branch': '[hash32]',
# Index in the deposit tree
'index': 'uint64',
# Data
'deposit_data': DepositData,
}
```
Expand All @@ -368,12 +368,12 @@ Unless otherwise indicated, code appearing in `this style` is to be interpreted

```python
{
# Deposit input
'deposit_input': DepositInput,
# Amount in Gwei
'amount': 'uint64',
# Timestamp from deposit contract
'timestamp': 'uint64',
# Deposit input
'deposit_input': DepositInput,
}
```

Expand Down Expand Up @@ -653,7 +653,7 @@ DEPOSIT_CONTRACT_TREE_DEPTH: constant(uint256) = 32
TWO_TO_POWER_OF_TREE_DEPTH: constant(uint256) = 4294967296 # 2**32
SECONDS_PER_DAY: constant(uint256) = 86400

Deposit: event({previous_deposit_root: bytes32, data: bytes[2064], deposit_count: uint256})
Deposit: event({previous_deposit_root: bytes32, data: bytes[2064], merkle_tree_index: bytes[8]})
ChainStart: event({deposit_root: bytes32, time: bytes[8]})

deposit_tree: map(uint256, bytes32)
Expand All @@ -670,8 +670,9 @@ def deposit(deposit_input: bytes[2048]):
msg_gwei_bytes8: bytes[8] = slice(concat("", convert(msg.value / GWEI_PER_ETH, bytes32)), start=24, len=8)
timestamp_bytes8: bytes[8] = slice(concat("", convert(block.timestamp, bytes32)), start=24, len=8)
deposit_data: bytes[2064] = concat(msg_gwei_bytes8, timestamp_bytes8, deposit_input)
merkle_tree_index: bytes[8] = slice(concat("", convert(index, bytes32)), start=24, len=8)

log.Deposit(self.deposit_tree[1], deposit_data, self.deposit_count)
log.Deposit(self.deposit_tree[1], deposit_data, merkle_tree_index)

# add deposit to merkle tree
self.deposit_tree[index] = sha3(deposit_data)
Expand Down Expand Up @@ -1470,11 +1471,12 @@ For each `attestation` in `block.body.attestations`:
Verify that `len(block.body.deposits) <= MAX_DEPOSITS`.

[TODO: add logic to ensure that deposits from 1.0 chain are processed in order]
[TODO: update the call to `verify_merkle_branch` below if it needs to change after we process deposits in order]

For each `deposit` in `block.body.deposits`:

* Let `serialized_deposit_data` be the serialized form of `deposit.deposit_data`. It should be the `DepositInput` followed by 8 bytes for `deposit_data.amount` and 8 bytes for `deposit_data.timestamp`. That is, it should match `deposit_data` in the [Ethereum 1.0 deposit contract](#ethereum-10-deposit-contract) of which the hash was placed into the Merkle tree.
* Use the following procedure to verify `deposit.merkle_branch`, setting `leaf=serialized_deposit_data`, `depth=DEPOSIT_CONTRACT_TREE_DEPTH` and `root=state.latest_deposit_root`:
* Let `serialized_deposit_data` be the serialized form of `deposit.deposit_data`. It should be 8 bytes for `deposit_data.amount` followed by 8 bytes for `deposit_data.timestamp` and then the `DepositInput` bytes. That is, it should match `deposit_data` in the [Ethereum 1.0 deposit contract](#ethereum-10-deposit-contract) of which the hash was placed into the Merkle tree.
* Verify that `verify_merkle_branch(hash(serialized_deposit_data), deposit.branch, DEPOSIT_CONTRACT_TREE_DEPTH, deposit.index, state.latest_deposit_root)` is `True`.

```python
def verify_merkle_branch(leaf: Hash32, branch: [Hash32], depth: int, index: int, root: Hash32) -> bool:
Expand Down