bitgesell-merkle-lib
v1.0.6
Published
A performance conscious library for merkle root and tree calculations for Bitgesell Blockchain network.
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bitgesell-merkle-lib
A performance conscious library for merkle root and tree calculations for Bitgesell Blockchain Network.
Disclaimer
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)
.
Additionally, this implementation is vulnerable to a forgery attack for an unbalanced merkle tree, wherein, in an unbalanced merkle tree, the last leaf node can be duplicated to create an artificial balanced tree, resulting in the same root hash. To avoid this vulnerability [in this implementation], do not accept unbalanced merkle trees in your application.
Usage
Preamble
const crypto = require('crypto')
function sha256 (data) {
return crypto.createHash('sha256').update(data).digest()
}
const data = [
'cafebeef',
'ffffffff',
'aaaaaaaa',
'bbbbbbbb',
'cccccccc'
].map(x => new Buffer(x, 'hex'))
// ... now, the examples
Tree
const { merkleTree } = require('bitgesell-merkle-lib')
const tree = merkleTree(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]
)
const {
fastRoot,
verify
} = require('bitgesell-merkle-lib')
const root = fastRoot(data, sha256)
console.log(root.toString('hex'))
// => 'c2692b0e127b3b774a92f6e1d8ff8c3a5ea9eef9a1d389fe294f0a7a2fec9be1'
Proof (with verify)
const {merkleProof} = require('bitgesell-merkle-lib')
const 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(verify(proof, sha256))
// => true
API
For an indepth documentation refer to docs also see usage for practical usage.
Tests
To run tests,
npm install
npm run unit
Credits
Thanks to Meni Rosenfield on bitcointalk for the math.