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eth2.0-specs
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Fixes bug with Merkle proof branch selection 

This code determines the order in which the next branch element and the
current value should be hashed to produce the parent node in the Merkle tree.

The existing code fails to verify branches constructed in the standard way.

This patch fixes the spec code so that it works properly by using an appropriate
parity calculation.

Example code here to illustrate it working:
https://gist.github.com/ralexstokes/9d82e188bd3286ff74a1fa1dcb5068e0
This commit is contained in:
Alex Stokes 2019-01-04 09:48:50 -06:00
parent 88de4e35f2
commit a0e454d86c
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specs/core/0_beacon-chain.md
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@ -1518,7 +1518,7 @@ For each `deposit` in `block.body.deposits`:
def verify_merkle_branch(leaf: Hash32, branch: [Hash32], depth: int, index: int, root: Hash32) -> bool: def verify_merkle_branch(leaf: Hash32, branch: [Hash32], depth: int, index: int, root: Hash32) -> bool:
value = leaf value = leaf
for i in range(depth): for i in range(depth):
if index % 2: if index // (2**i) % 2:
value = hash(branch[i] + value) value = hash(branch[i] + value)
else: else:
value = hash(value + branch[i]) value = hash(value + branch[i])