nimbus-eth2/tests/test_ssz_merkleization.nim

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import
std/[strutils, sequtils, macros, bitops],
stew/[bitops2, endians2],
../beacon_chain/spec/[beaconstate, datatypes, digest, helpers],
../beacon_chain/[ssz, merkle_minimal],
mocking/mock_deposits
func round_step_down(x: Natural, step: static Natural): int =
## Round the input to the previous multiple of "step"
when (step and (step - 1)) == 0:
# Step is a power of 2. (If compiler cannot prove that x>0 it does not make the optim)
x and not(step - 1)
else:
x - x mod step
type SparseMerkleTree[Depth: static int] = object
## Sparse Merkle tree
# There is an extra "depth" layer to store leaf nodes
# This stores leaves at depth = 0
# and the root hash at the last depth
nnznodes*: array[Depth+1, seq[Eth2Digest]] # nodes that leads to non-zero leaves
func merkleTreeFromLeaves(
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values: openArray[Eth2Digest],
Depth: static[int] = DEPOSIT_CONTRACT_TREE_DEPTH
): SparseMerkleTree[Depth] =
## Depth should be the same as is_valid_merkle_branch
result.nnznodes[0] = @values
for depth in 1 .. Depth: # Inclusive range
let prev_depth_len = result.nnznodes[depth-1].len
let stop = round_step_down(prev_depth_len, 2)
for i in countup(0, stop-1, 2):
# hash by pair of previous nodes
let nodeHash = withEth2Hash:
h.update result.nnznodes[depth-1][i]
h.update result.nnznodes[depth-1][i+1]
result.nnznodes[depth].add nodeHash
if prev_depth_len != stop:
# If length is odd, the last one was skipped,
# we need to combine it
# with the zeroHash corresponding to the current depth
let nodeHash = withEth2Hash:
h.update result.nnznodes[depth-1][^1]
h.update zeroHashes[depth-1]
result.nnznodes[depth].add nodeHash
func getMerkleProof[Depth: static int](tree: SparseMerkleTree[Depth],
index: int,
depositMode = false): array[Depth, Eth2Digest] =
# Descend down the tree according to the bit representation
# of the index:
# - 0 --> go left
# - 1 --> go right
let path = uint32(index)
# This is what the nnznodes[depth].len would be if `index` had been the last
# deposit on the Merkle tree
var depthLen = index + 1
for depth in 0 ..< Depth:
let nodeIdx = int((path shr depth) xor 1)
# depositMode simulates only having constructed SparseMerkleTree[Depth]
# through exactly deposit specified.
if nodeIdx < tree.nnznodes[depth].len and
(nodeIdx < depthLen or not depositMode):
result[depth] = tree.nnznodes[depth][nodeIdx]
else:
result[depth] = zeroHashes[depth]
# Round up, i.e. a half-pair of Merkle nodes/leaves still requires a node
# in the next Merkle tree layer calculated
depthLen = (depthLen + 1) div 2
proc testMerkleMinimal*(): bool =
proc toDigest[N: static int](x: array[N, byte]): Eth2Digest =
result.data[0 .. N-1] = x
let a = [byte 0x01, 0x02, 0x03].toDigest
let b = [byte 0x04, 0x05, 0x06].toDigest
let c = [byte 0x07, 0x08, 0x09].toDigest
block: # SSZ Sanity checks vs Python impl
block: # 3 leaves
let leaves = List[Eth2Digest, 3](@[a, b, c])
let root = hash_tree_root(leaves)
doAssert $root == "9ff412e827b7c9d40fc7df2725021fd579ab762581d1ff5c270316682868456e".toUpperAscii
block: # 2^3 leaves
let leaves = List[Eth2Digest, int64(1 shl 3)](@[a, b, c])
let root = hash_tree_root(leaves)
doAssert $root == "5248085b588fab1dd1e03f3cd62201602b12e6560665935964f46e805977e8c5".toUpperAscii
block: # 2^10 leaves
let leaves = List[Eth2Digest, int64(1 shl 10)](@[a, b, c])
let root = hash_tree_root(leaves)
doAssert $root == "9fb7d518368dc14e8cc588fb3fd2749beef9f493fef70ae34af5721543c67173".toUpperAscii
block:
macro roundTrips(): untyped =
result = newStmtList()
# compile-time unrolled test
for nleaves in [3, 4, 5, 7, 8, 1 shl 10, 1 shl 32]:
let depth = fastLog2(nleaves-1) + 1
result.add quote do:
block:
let tree = merkleTreeFromLeaves([a, b, c], Depth = `depth`)
#echo "Tree: ", tree
doAssert tree.nnznodes[`depth`].len == 1
let root = tree.nnznodes[`depth`][0]
#echo "Root: ", root
block: # proof for a
let index = 0
doAssert is_valid_merkle_branch(
a, tree.getMerkleProof(index = index),
depth = `depth`,
index = index.uint64,
root = root
), "Failed (depth: " & $`depth` &
", nleaves: " & $`nleaves` & ')'
block: # proof for b
let index = 1
doAssert is_valid_merkle_branch(
b, tree.getMerkleProof(index = index),
depth = `depth`,
index = index.uint64,
root = root
), "Failed (depth: " & $`depth` &
", nleaves: " & $`nleaves` & ')'
block: # proof for c
let index = 2
doAssert is_valid_merkle_branch(
c, tree.getMerkleProof(index = index),
depth = `depth`,
index = index.uint64,
root = root
), "Failed (depth: " & $`depth` &
", nleaves: " & $`nleaves` & ')'
roundTrips()
true
doAssert testMerkleMinimal()
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proc compareTreeVsMerkleizer(hashes: openArray[Eth2Digest], limit: static Limit) =
const treeHeight = binaryTreeHeight(limit)
let tree = merkleTreeFromLeaves(hashes, treeHeight)
var merkleizer = createMerkleizer(limit)
for hash in hashes:
merkleizer.addChunk hash.data
doAssert merkleizer.getFinalHash() == tree.nnznodes[treeHeight - 1][0]
proc testMultiProofsGeneration(preludeRecords: int,
totalProofs: int,
followUpRecords: int,
limit: static Limit) =
var
m1 = createMerkleizer(limit)
m2 = createMerkleizer(limit)
var preludeHashes = newSeq[Eth2Digest]()
for i in 0 ..< preludeRecords:
let hash = eth2digest toBytesLE(uint64(100000000 + i))
m1.addChunk hash.data
m2.addChunk hash.data
preludeHashes.add hash
var proofsHashes = newSeq[Eth2Digest]()
for i in 0 ..< totalProofs:
let hash = eth2digest toBytesLE(uint64(200000000 + i))
m1.addChunk hash.data
proofsHashes.add hash
var proofs = addChunksAndGenMerkleProofs(m2, proofsHashes)
const treeHeight = binaryTreeHeight(limit)
let merkleTree = merkleTreeFromLeaves(preludeHashes & proofsHashes,
treeHeight)
doAssert m1.getFinalHash == merkleTree.nnznodes[treeHeight - 1][0]
doAssert m1.getFinalHash == m2.getFinalHash
for i in 0 ..< totalProofs:
let
referenceProof = merkle_tree.getMerkleProof(preludeRecords + i, false)
startPos = i * treeHeight
endPos = startPos + treeHeight - 1
doAssert referenceProof == proofs.toOpenArray(startPos, endPos)
for i in 0 ..< followUpRecords:
let hash = eth2digest toBytesLE(uint64(300000000 + i))
m1.addChunk hash.data
m2.addChunk hash.data
doAssert m1.getFinalHash == m2.getFinalHash
for prelude in [0, 1, 2, 5, 6, 12, 13, 16]:
for proofs in [1, 2, 4, 17, 64]:
for followUpHashes in [0, 1, 2, 5, 7, 8, 15, 48]:
testMultiProofsGeneration(prelude, proofs, followUpHashes, 128)
testMultiProofsGeneration(prelude, proofs, followUpHashes, 5000)
iterator hash_tree_roots_prefix[T](lst: openArray[T],
limit: static Limit): Eth2Digest =
# This is a particular type's instantiation of a general fold, reduce,
# accumulation, prefix sums, etc family of operations. As long as that
# Eth1 deposit case is the only notable example -- the usual uses of a
# list involve, at some point, tree-hashing it -- finalized hashes are
# the only abstraction that escapes from this module this way.
var merkleizer = createMerkleizer(limit)
for i, elem in lst:
merkleizer.addChunk(hash_tree_root(elem).data)
yield mixInLength(merkleizer.getFinalHash(), i + 1)
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func attachMerkleProofsReferenceImpl(deposits: var openArray[Deposit]) =
let
deposit_data_roots = mapIt(deposits, it.data.hash_tree_root)
merkle_tree = merkleTreeFromLeaves(deposit_data_roots)
var
deposit_data_sums: seq[Eth2Digest]
for prefix_root in hash_tree_roots_prefix(
deposit_data_roots, 1'i64 shl DEPOSIT_CONTRACT_TREE_DEPTH):
deposit_data_sums.add prefix_root
for val_idx in 0 ..< deposits.len:
deposits[val_idx].proof[0..31] = merkle_tree.getMerkleProof(val_idx, true)
deposits[val_idx].proof[32] = default(Eth2Digest)
deposits[val_idx].proof[32].data[0..7] = uint_to_bytes8((val_idx + 1).uint64)
doAssert is_valid_merkle_branch(
deposit_data_roots[val_idx], deposits[val_idx].proof,
DEPOSIT_CONTRACT_TREE_DEPTH + 1, val_idx.uint64,
deposit_data_sums[val_idx])
let
digests = mapIt(1..65, eth2digest toBytesLE(uint64 it))
proc testMerkleizer =
for i in 0 ..< digests.len:
compareTreeVsMerkleizer(digests.toOpenArray(0, i), 128)
compareTreeVsMerkleizer(digests.toOpenArray(0, i), 5000)
var deposits = mockGenesisBalancedDeposits(65, 100000)
var depositsCopy = deposits
attachMerkleProofsReferenceImpl(deposits)
attachMerkleProofs(depositsCopy)
for i in 0 ..< deposits.len:
doAssert deposits[i].proof == depositsCopy[i].proof
testMerkleizer()