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m-tree

0.0.7 • Public • Published

MOVED TO merkletreejs

THIS NPM MODULE IS NOW DEPRECATED. IT'S MOVED TO merkletreejs


Merkle Tree


Construct Merkle Trees and verify proofs in JavaScript.

Diagram of Merkle Tree

Merkle Tree

Diagram of Merkle Tree Proof

Merkle Tree Proof

Diagram of Invalid Merkle Tree Proofs

Merkle Tree Proof

Diagram of Bitcoin Merkle Tree

Merkle Tree Proof

Install

npm install m-tree

Classes

MerkleTree

Objects

MerkleTree : object

Class reprensenting a Merkle Tree

MerkleTree

Kind: global class


new MerkleTree(leaves, hashAlgorithm, options)

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.

Param Type Description
leaves Array.<Buffer> Array of hashed leaves. Each leaf must be a Buffer.
hashAlgorithm function Algorithm used for hashing leaves and nodes
options Object Additional options
options.isBitcoinTree Boolean If set to true, constructs the Merkle Tree using the Bitcoin Merkle Tree implementation. Enable it when you need to replicate Bitcoin constructed Merkle Trees. In Bitcoin Merkle Trees, single nodes are combined with themselves, and each output hash is hashed again.

Example

const MerkleTree = require('m-tree')
const crypto = require('crypto')
 
function sha256(data) {
  // returns Buffer
  return crypto.createHash('sha256').update(data).digest()
}
 
const leaves = ['a', 'b', 'c'].map(x => sha3(x))
 
const tree = new MerkleTree(leaves, sha256)

merkleTree.getLeaves() ⇒ Array.<Buffer>

Returns array of leaves of Merkle Tree.

Kind: instance method of MerkleTree Example

const leaves = tree.getLeaves()

merkleTree.getLayers() ⇒ Array.<Buffer>

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

Kind: instance method of MerkleTree Example

const layers = tree.getLayers()

merkleTree.getRoot() ⇒ Buffer

Returns the Merkle root hash as a Buffer.

Kind: instance method of MerkleTree Example

const root = tree.getRoot()

merkleTree.getProof(leaf, [index]) ⇒ Array.<Buffer>

Returns the proof for a target leaf.

Kind: instance method of MerkleTree Returns: Array.<Buffer> - - Array of Buffer hashes.

Param Type Description
leaf Buffer Target leaf
[index] Number Target leaf index in leaves array. Use if there are leaves containing duplicate data in order to distinguish it.

Example

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

Example

const leaves = ['a', 'b', 'a'].map(x => sha3(x))
const tree = new MerkleTree(leaves, sha3)
const proof = tree.getProof(leaves[2], 2)

merkleTree.verify(proof, targetNode, root) ⇒ Boolean

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

Kind: instance method of MerkleTree

Param Type Description
proof Array.<Buffer> Array of proof Buffer hashes that should connect target node to Merkle root.
targetNode Buffer Target node Buffer
root Buffer Merkle root Buffer

Example

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

MerkleTree : object

Class reprensenting a Merkle Tree

Kind: global namespace


new MerkleTree(leaves, hashAlgorithm, options)

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.

Param Type Description
leaves Array.<Buffer> Array of hashed leaves. Each leaf must be a Buffer.
hashAlgorithm function Algorithm used for hashing leaves and nodes
options Object Additional options
options.isBitcoinTree Boolean If set to true, constructs the Merkle Tree using the Bitcoin Merkle Tree implementation. Enable it when you need to replicate Bitcoin constructed Merkle Trees. In Bitcoin Merkle Trees, single nodes are combined with themselves, and each output hash is hashed again.

Example

const MerkleTree = require('m-tree')
const crypto = require('crypto')
 
function sha256(data) {
  // returns Buffer
  return crypto.createHash('sha256').update(data).digest()
}
 
const leaves = ['a', 'b', 'c'].map(x => sha3(x))
 
const tree = new MerkleTree(leaves, sha256)

merkleTree.getLeaves() ⇒ Array.<Buffer>

Returns array of leaves of Merkle Tree.

Kind: instance method of MerkleTree Example

const leaves = tree.getLeaves()

merkleTree.getLayers() ⇒ Array.<Buffer>

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

Kind: instance method of MerkleTree Example

const layers = tree.getLayers()

merkleTree.getRoot() ⇒ Buffer

Returns the Merkle root hash as a Buffer.

Kind: instance method of MerkleTree Example

const root = tree.getRoot()

merkleTree.getProof(leaf, [index]) ⇒ Array.<Buffer>

Returns the proof for a target leaf.

Kind: instance method of MerkleTree Returns: Array.<Buffer> - - Array of Buffer hashes.

Param Type Description
leaf Buffer Target leaf
[index] Number Target leaf index in leaves array. Use if there are leaves containing duplicate data in order to distinguish it.

Example

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

Example

const leaves = ['a', 'b', 'a'].map(x => sha3(x))
const tree = new MerkleTree(leaves, sha3)
const proof = tree.getProof(leaves[2], 2)

merkleTree.verify(proof, targetNode, root) ⇒ Boolean

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

Kind: instance method of MerkleTree

Param Type Description
proof Array.<Buffer> Array of proof Buffer hashes that should connect target node to Merkle root.
targetNode Buffer Target node Buffer
root Buffer Merkle root Buffer

Example

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

Test

npm test

Notes

As is, this implemenation is vulnerable to a second pre-image attack. Use a difference hashing algorithm function for leaves and nodes, so that H(x) != H'(x).

Also, as is, this implementation is vulnerable to a forgery attack for an unbalanced tree, where the last leaf node can be duplicated to create an artificial balanced tree, resulting in the same Merkle root hash. Do not accept unbalanced tree to prevent this.

Resources

License

MIT

Install

npm i m-tree

DownloadsWeekly Downloads

3

Version

0.0.7

License

MIT

Unpacked Size

250 kB

Total Files

17

Last publish

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