Class MerkleTreeNamespace

Desc

Constructs a Merkle Tree. All nodes and leaves are stored as Buffers. Lonely leaf nodes are promoted to the next level up without being hashed again.

Example

const MerkleTree = require('merkletreejs')
const crypto = require('crypto')

function sha256(data) {
 // returns Buffer
 return crypto.createHash('sha256').update(data).digest()
}

const leaves = ['a', 'b', 'c'].map(value => keccak(value))

const tree = new MerkleTree(leaves, sha256)
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addLeaf

Desc

Adds a leaf to the tree and re-calculates layers.

Example

tree.addLeaf(newLeaf)
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addLeaves

Desc

Adds multiple leaves to the tree and re-calculates layers.

Example

tree.addLeaves(newLeaves)
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getDepth

Desc

Returns the tree depth (number of layers)

Example

const depth = tree.getDepth()
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getHexLayers

Desc

Returns multi-dimensional array of all layers of Merkle Tree, including leaves and root as hex strings.

Example

const layers = tree.getHexLayers()
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getHexLayersFlat

Desc

Returns single flat array of all layers of Merkle Tree, including leaves and root as hex string.

Example

const layers = tree.getHexLayersFlat()
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getHexLeaves

Desc

Returns array of leaves of Merkle Tree as hex strings.

Example

const leaves = tree.getHexLeaves()
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getHexMultiProof

Desc

Returns the multiproof for given tree indices as hex strings.

Example

const indices = [2, 5, 6]
const proof = tree.getHexMultiProof(indices)
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getHexProof

Desc

Returns the proof for a target leaf as hex strings.

Example

const proof = tree.getHexProof(leaves[2])
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getHexProofs

Desc

Returns the proofs for all leaves as hex strings.

Example

const proofs = tree.getHexProofs()
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getHexRoot

Desc

Returns the Merkle root hash as a hex string.

Example

const root = tree.getHexRoot()
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getLayerCount

Desc

Returns the total number of layers.

Example

const count = tree.getLayerCount()
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getLayers

Desc

Returns multi-dimensional array of all layers of Merkle Tree, including leaves and root.

Example

const layers = tree.getLayers()
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getLayersAsObject

Desc

Returns the layers as nested objects instead of an array.

Example

const layersObj = tree.getLayersAsObject()
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getLayersFlat

Desc

Returns single flat array of all layers of Merkle Tree, including leaves and root.

Example

const layers = tree.getLayersFlat()
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getLeaf

Desc

Returns the leaf at the given index.

Example

const leaf = tree.getLeaf(1)
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getLeafCount

Desc

Returns the total number of leaves.

Example

const count = tree.getLeafCount()
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getLeafIndex

Desc

Returns the index of the given leaf, or -1 if the leaf is not found.

Example

const leaf = Buffer.from('abc')
const index = tree.getLeafIndex(leaf)
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getLeaves

Desc

Returns array of leaves of Merkle Tree.

Example

const leaves = tree.getLeaves()
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getMultiProof

Desc

Returns the multiproof for given tree indices.

Example

const indices = [2, 5, 6]
const proof = tree.getMultiProof(indices)
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getPositionalHexProof

Desc

Returns the proof for a target leaf as hex strings and the position in binary (left == 0).

Example

const proof = tree.getPositionalHexProof(leaves[2])
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getProof

Desc

Returns the proof for a target leaf.

Example

const proof = tree.getProof(leaves[2])
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Example

const leaves = ['a', 'b', 'a'].map(value => keccak(value))
const tree = new MerkleTree(leaves, keccak)
const proof = tree.getProof(leaves[2], 2)
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getProofFlags

Desc

Returns list of booleans where proofs should be used instead of hashing. Proof flags are used in the Solidity multiproof verifiers.

Example

const indices = [2, 5, 6]
const proof = tree.getMultiProof(indices)
const proofFlags = tree.getProofFlags(leaves, proof)
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getProofIndices

Desc

Returns the proof indices for given tree indices.

Example

const proofIndices = tree.getProofIndices([2,5,6], 4)
console.log(proofIndices) // [ 23, 20, 19, 8, 3 ]
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getProofs

Desc

Returns the proofs for all leaves.

Example

const proofs = tree.getProofs()
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Example

const leaves = ['a', 'b', 'a'].map(value => keccak(value))
const tree = new MerkleTree(leaves, keccak)
const proofs = tree.getProofs()
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getProofsDFS

Desc

Get all proofs through single traverse

Example

const layers = tree.getLayers()
const index = 0;
let proof = [];
let proofs = [];
const proof = tree.getProofsDFS(layers, index, proof, proofs)
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getRoot

Desc

Returns the Merkle root hash as a Buffer.

Example

const root = tree.getRoot()
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resetTree

Desc

Resets the tree by clearing the leaves and layers.

Example

tree.resetTree()
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toString

Desc

Returns a visual representation of the merkle tree as a string.

Example

console.log(tree.toString())
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verify

Desc

Returns true if the proof path (array of hashes) can connect the target node to the Merkle root.

Example

const root = tree.getRoot()
const proof = tree.getProof(leaves[2])
const verified = tree.verify(proof, leaves[2], root)
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verifyMultiProof

Desc

Returns true if the multiproofs can connect the leaves to the Merkle root.

Example

const leaves = tree.getLeaves()
const root = tree.getRoot()
const treeFlat = tree.getLayersFlat()
const leavesCount = leaves.length
const proofIndices = [2, 5, 6]
const proofLeaves = proofIndices.map(i => leaves[i])
const proof = tree.getMultiProof(treeFlat, indices)
const verified = tree.verifyMultiProof(root, proofIndices, proofLeaves, leavesCount, proof)
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getMultiProof

Desc

Returns the multiproof for given tree indices.

Example

const flatTree = tree.getLayersFlat()
const indices = [2, 5, 6]
const proof = MerkleTree.getMultiProof(flatTree, indices)
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marshalLeaves

Desc

Returns array of leaves of Merkle Tree as a JSON string.

Example

const jsonStr = MerkleTree.marshalLeaves(leaves)
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marshalProof

Desc

Returns proof array as JSON string.

Example

const jsonStr = MerkleTree.marshalProof(proof)
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unmarshalLeaves

Desc

Returns array of leaves of Merkle Tree as a Buffers.

Example

const leaves = MerkleTree.unmarshalLeaves(jsonStr)
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unmarshalProof

Desc

Returns the proof for a target leaf as a list of Buffers.

Example

const proof = MerkleTree.unmarshalProof(jsonStr)
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verify

Desc

Returns true if the proof path (array of hashes) can connect the target node to the Merkle root.

Example

const verified = MerkleTree.verify(proof, leaf, root, sha256, options)
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