blockchain-spv

Stores blockchain headers and verifies transactions with SPV

Usage no npm install needed!

<script type="module">
  import blockchainSpv from 'https://cdn.skypack.dev/blockchain-spv';
</script>

README

blockchain-spv

npm version Build Status Dependency Status

SPV Bitcoin blockchain verifier

Usage

npm install blockchain-spv

let Blockchain = require('blockchain-spv')

let bitcoinGenesis = {
  height: 0,
  version: 1,
  prevHash: Buffer.alloc(32),
  merkleRoot: Buffer.from('4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b', 'hex').reverse(),
  timestamp: 1231006505,
  bits: 0x1d00ffff,
  nonce: 2083236893
}

let chain = new Blockchain({
  start: bitcoinGenesis
})

// add arrays of headers, throws if invalid
chain.add(header)

Blockchain stores and verifies block headers, and does SPV (light client) verification. It is compatible with Bitcoin and Bitcoin-derived blockchains.

new Blockchain(opts)

Creates an SPV Blockchain which stores and verifies block headers.

opts can contain:

  • start - a header to be used as the starting point (e.g. the genesis or a checkpoint)
  • store (optional) an array where the verified chain of headers should be stored
  • indexed (default: false) whether or not to index headers by their hash, enabling the getByHash method
  • maxTarget (default: Bitcoin maxTarget) a maximum difficulty target value as a 32-byte Buffer, should only be changed to make mining easier for writing tests

chain.add(headers, now = Date.now())

Adds block headers to the chain. headers should be an array of contiguous, ascending block headers. now is an optional argument that should be the current time in milliseconds. The headers will be verified (checked to make sure the expected amount of work was done, the difficulty was correct, etc.), then added to the store if valid. An error will be thrown if there is a validation error.

The headers can contain a reorg (e.g. they don't connect to chain's current tip).

chain.getByHeight(height)

Gets a header in the chain with height height. If the header isn't found, an error is thrown. This runs in O(1).

chain.getByHash(hash)

Gets a header in the chain with hash hash (either a Buffer or a hex string). If the header isn't found or indexing was not enabled (see the Blockchain constructor), an error is thrown. This runs in O(1).

chain.height()

Returns the height of the highest block added to the chain.