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merkle-lib
Advanced tools
Readme
A performance conscious library for merkle root and tree calculations.
NOTE: As is, this implementation is vulnerable to a forgery attack (as a second pre-image attack), see these[1][2] crypto.stackexchange questions for an explanation.
To avoid this vulnerability, you should pre-hash your leaves using a different hash function than the function provided such that H(x) != H'(x)
.
Preamble
var crypto = require('crypto')
function sha256 (data) {
return crypto.createHash('sha256').update(data).digest()
}
var data = [
'cafebeef',
'ffffffff',
'aaaaaaaa',
'bbbbbbbb',
'cccccccc'
].map(x => new Buffer(x, 'hex'))
// ... now, the examples
Tree
var merkle = require('merkle-lib')
var tree = merkle(data, sha256)
console.log(tree.map(x => x.toString('hex')))
// => [
// 'cafebeef',
// 'ffffffff',
// 'aaaaaaaa',
// 'bbbbbbbb',
// 'cccccccc',
// 'bda5c39dec343da54ce91c57bf8e796c2ca16a1bd8cae6a2cefbdd16efc32578',
// '8b722baf6775a313f1032ba9984c0dce32ff3c40d7a67b5df8de4dbaa43a3db0',
// '3d2f424783df5853c8d7121b1371650c04241f318e1b0cd46bedbc805b9164c3',
// 'bb232963fd0efdeacb0fd76e26cf69055fa5facc19a5f5c2f2f27a6925d1db2f',
// '2256e70bea2c591190a0d4d6c1415acd7458fae84d8d85cdc68b851da27777d4',
// 'c2692b0e127b3b774a92f6e1d8ff8c3a5ea9eef9a1d389fe294f0a7a2fec9be1'
//]
Root only (equivalent to tree[tree.length - 1]
)
var fastRoot = require('merkle-lib/fastRoot')
var root = fastRoot(data, sha256)
console.log(root.toString('hex'))
// => 'c2692b0e127b3b774a92f6e1d8ff8c3a5ea9eef9a1d389fe294f0a7a2fec9be1'
Proof (with verify)
var merkleProof = require('merkle-lib/proof')
var proof = merkleProof(tree, data[0])
if (proof === null) {
console.error('No proof exists!')
}
console.log(proof.map(x => x && x.toString('hex')))
// => [
// 'cafebeef',
// 'ffffffff',
// null,
// '8b722baf6775a313f1032ba9984c0dce32ff3c40d7a67b5df8de4dbaa43a3db0',
// null,
// '2256e70bea2c591190a0d4d6c1415acd7458fae84d8d85cdc68b851da27777d4',
// 'c2692b0e127b3b774a92f6e1d8ff8c3a5ea9eef9a1d389fe294f0a7a2fec9be1'
// ]
console.log(merkleProof.verify(proof, sha256))
// => true
Thanks to Meni Rosenfield on bitcointalk for the math.
FAQs
A performance conscious library for merkle root and tree calculations.
The npm package merkle-lib receives a total of 23,656 weekly downloads. As such, merkle-lib popularity was classified as popular.
We found that merkle-lib demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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