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IPLD for Bitcoin

JavaScript Bitcoin data multiformats codecs and utilities for IPLD

About

This codec is intended to be used with multiformats. It provides decode and encode functionality for the Bitcoin native format to and from IPLD.

The following IPLD codecs are available; they each support encode() and decode() functionality compatible with the multiformats BlockCodec type.

Codecs

bitcoin-block

bitcoin-block / 0xb0 is the Bitcoin block header, commonly identified by "Bitcoin block identifiers" (hashes with leading zeros).

import * as bitcoinBlock from '@ipld/bitcoin/block'

bitcoin-tx

bitcoin-tx / 0xb1 are Bitcoin transactions and nodes in a binary merkle tree, the tip of which is referenced by the Bitcoin block header.

import * as bitcoinTx from '@ipld/bitcoin/tx'

bitcoin-witness-commitment

bitcoin-witness-commitment / 0xb2 is the Bitcoin witness commitment that is used to reference transactions with intact witness data (a complication introduced by SegWit).

import * as bitcoinWitnessCommitment from '@ipld/bitcoin/witness-commitment'

Hasher

The following multihash is available, compatible with the multiformats MultihashHasher type.

dbl-sha2-256

dbl-sha2-256 / 0x56 is a double SHA2-256 hash: SHA2-256(SHA2-256(bytes)), used natively across all Bitcoin blocks, forming block identifiers, transaction identifiers and hashes and binary merkle tree nodes.

import * as dblSha2256 from '@ipld/bitcoin/dbl-sha2-256'

Utilities

In addition to the multiformats codecs and hasher, utilities are also provided to convert between Bitcoin hash identifiers and CIDs and to convert to and from full Bitcoin raw block data to a full collection of IPLD blocks. Additional conversion functionality for bitcoin raw data and the bitcoin-cli JSON format is provided by the bitcoin-block library.

See the API section below for details on the additional utility functions.

Example

This example reads Bitcoin IPLD blocks from a CAR file; assuming that CAR contains a complete (enough) graph representing a Bitcoin block (whose identifier is supplied as the second argument) and its transactions, it navigates to the first transaction (the Coinbase) and prints the scriptSig as UTF-8. This is often used to store arbitrary messages and other "graffiti".

Running this example on the Genesis block (CAR provided in this project: example-genesis.car) produces the following output:

$ node example.js ./example-genesis.car 000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f
��EThe Times 03/Jan/2009 Chancellor on brink of second bailout for banks

import fs from 'fs'
import * as bitcoinBlock from '@ipld/bitcoin/block'
import * as bitcoinTx from '@ipld/bitcoin/tx'
import { CarReader } from '@ipld/car'

// Assumes a CAR with at least one full Bitcoin block represented as IPLD blocks
// and a "blockId" which is the commonly used Bitcoin block identifier (32-byte
// digest in hexadecimal, with leading zeros).
async function run (pathToCar, blockId) {
  const reader = await CarReader.fromIterable(fs.createReadStream(pathToCar))
  const headerCid = bitcoinBlock.blockHashToCID(blockId)
  const header = bitcoinBlock.decode((await reader.get(headerCid)).bytes)

  // navigate the transaction binary merkle tree to the first transaction, the coinbase,
  // which will be at the leftmost side of the tree.
  let txCid = header.tx
  let tx
  while (true) {
    tx = bitcoinTx.decode((await reader.get(txCid)).bytes)
    if (!Array.isArray(tx)) { // is not an inner merkle tree node
      break
    }
    txCid = tx[0] // leftmost side of the tx binary merkle
  }

  // convert the scriptSig to UTF-8 and cross our fingers that there's something
  // interesting in there
  console.log(Buffer.from(tx.vin[0].coinbase, 'hex').toString('utf8'))
}

run(process.argv[2], process.argv[3]).catch((err) => {
  console.error(err.stack)
  process.exit(1)
})

Usage

In the API docs below, the names denote the export locations, such that they may be obtained by the following:

// The whole bundle (note this object also includes additional properties that
// can be used to access all the others)
import * as Bitcoin from '@ipld/bitcoin'
// the `bitcoin-block` / `0xb0` codec
import * as BitcoinBlock from '@ipld/bitcoin/block'
// the `bitcoin-tx` / `0xb1` codec
import * as BitcoinTransaction from '@ipld/bitcoin/tx'
// the `bitcoin-witness-commitment` / `0xb2` codec
import * as BitcoinWitnessCommitment from '@ipld/bitcoin/witness-commitment'
// the `dbl-sha2-256` / `0x56` multihasher
import * as DblSha2256 from '@ipld/bitcoin/dbl-sha2-256'

API

Contents

<a name="Bitcoin__deserializeFullBitcoinBytes____"></a>

Bitcoin.deserializeFullBitcoinBytes()(bytes)

Instantiate a full object form from a full Bitcoin block graph binary representation. This binary form is typically extracted from a Bitcoin network node, such as with the Bitcoin Core bitcoin-cli getblock <identifier> 0 command (which outputs hexadecimal form and therefore needs to be decoded prior to handing to this function). This full binary form can also be obtained from the utility assemble function which can construct the full graph form of a Bitcoin block from the full IPLD block graph.

The object returned, if passed through JSON.stringify() should be identical to the JSON form provided by the Bitcoin Core bitcoin-cli getblock <identifier> 2 command (minus some chain-context elements that are not possible to derive without the full blockchain).

<a name="Bitcoin__serializeFullBitcoinBytes____"></a>

Bitcoin.serializeFullBitcoinBytes()(obj)

Encode a full object form of a Bitcoin block graph into its binary equivalent. This is the inverse of Bitcoin.deserializeFullBitcoinBytes() and should produce the exact binary representation of a Bitcoin block graph given the complete input.

The object form must include both the header and full transaction (including witness data) data for it to be properly serialized.

As of writing, the witness merkle nonce is not currently present in the JSON output from Bitcoin Core's bitcoin-cli. See https://github.com/bitcoin/bitcoin/pull/18826 for more information. Without this nonce, the exact binary form cannot be fully generated.

<a name="Bitcoin__cidToHash____"></a>

Bitcoin.cidToHash()(cid)

Convert a CID to a Bitcoin block or transaction identifier. This process is the reverse of blockHashToCID() and txHashToCID() and involves extracting and decoding the multihash from the CID, reversing the bytes and presenting it as a big-endian hexadecimal string.

Works for both block identifiers and transaction identifiers.

<a name="Bitcoin__encodeAll____"></a>

Bitcoin.encodeAll()

Encodes a full Bitcoin block, as presented in BlockPorcelain form (which is available as JSON output from the bitcoin-cli tool—see the bitcoin-block npm package for more information) into its constituent IPLD blocks. This includes the header, the transaction merkle intermediate nodes, the transactions and SegWit forms of the transaction merkle and nodes if present along with the witness commitment block if required.

<a name="Bitcoin__assemble____"></a>

Bitcoin.assemble()

Given a CID for a bitcoin-block Bitcoin block header and an IPLD block loader that can retrieve Bitcoin IPLD blocks by CID, re-assemble a full Bitcoin block graph into both object and binary forms. This is the inverse of the Bitcoin.encodeAll() function in that it puts the BitcoinPorcelain back together. A JSON form of this output should match the output provided by bitcoin-cli (with some possible minor differences).

The loader should be able to return the binary form for bitcoin-block, bitcoin-tx and bitcoin-witness-commitment CIDs.

<a name="BitcoinBlock__encode____"></a>

BitcoinBlock.encode()

bitcoin-block / 0xb0 codec: Encodes an IPLD node representing a Bitcoin header object into byte form.

<a name="BitcoinBlock__decode____"></a>

BitcoinBlock.decode()

bitcoin-block / 0xb0 codec: Decodes a bytes form of a Bitcoin header into an IPLD node representation.

<a name="BitcoinBlock__name"></a>

BitcoinBlock.name

bitcoin-block / 0xb0 codec: the codec name

<a name="BitcoinBlock__code"></a>

BitcoinBlock.code

bitcoin-block / 0xb0 codec: the codec code

<a name="BitcoinBlock__blockHashToCID____"></a>

BitcoinBlock.blockHashToCID()

Convert a Bitcoin block identifier (hash) to a CID. The identifier should be in big-endian form, i.e. with leading zeros.

The process of converting to a CID involves reversing the hash (to little-endian form), encoding as a dbl-sha2-256 multihash and encoding as a bitcoin-block multicodec. This process is reversable, see cidToHash.

<a name="BitcoinTransaction__encode____"></a>

BitcoinTransaction.encode()

bitcoin-tx / 0xb1 codec: Encodes an IPLD node representing a Bitcoin transaction object into byte form.

Note that a bitcoin-tx IPLD node can either be a full transaction with or without SegWit data, or an intermediate transaction Merkle tree node; in which case it is simply an array of two CIDs.

<a name="BitcoinTransaction__encodeNoWitness____"></a>

BitcoinTransaction.encodeNoWitness()

Same as BitcoinTransaction.encode() but will explictly exclude any witness (SegWit) data from the output. This is necessary for encoding SegWit blocks since transactions must be stored both with and without witness data to correctly represent the full content addressed structure.

<a name="BitcoinTransaction__encodeAll____"></a>

BitcoinTransaction.encodeAll()

Encodes all transactions in a complete BlockPorcelain (see the bitcoin-block npm package for details on this type) representation of an entire Bitcoin transaction; including intermediate Merkle tree nodes.

Intermediate Merkle tree nodes won't have the transaction property on the output as they aren't full transactions and their bytes will have a length of 64.

<a name="BitcoinTransaction__encodeAllNoWitness____"></a>

BitcoinTransaction.encodeAllNoWitness()

Same as BitcoinTransaction.encodeAll() but only encodes non-SegWit transaction data, that is, transactions without witness data and no secondary SegWit transactions Merkle tree.

<a name="BitcoinTransaction__decode____"></a>

BitcoinTransaction.decode()

bitcoin-block / 0xb0 codec: Decodes a bytes form of a Bitcoin transaction into an IPLD node representation.

Note that a bitcoin-tx IPLD node can either be a full transaction with or without SegWit data, or an intermediate transaction Merkle tree node; in which case it is simply an array of two CIDs. As byte form, an intermediate Merkle tree node is a fixed 64-bytes.

<a name="BitcoinTransaction__name"></a>

BitcoinTransaction.name

bitcoin-tx / 0xb1 codec: the codec name

<a name="BitcoinTransaction__name"></a>

BitcoinTransaction.name

bitcoin-tx / 0xb1 codec: the codec name

<a name="BitcoinTransaction__txHashToCID____"></a>

BitcoinTransaction.txHashToCID()

Convert a Bitcoin transaction identifier (hash) to a CID. The identifier should be in big-endian form as typically understood by Bitcoin applications.

The process of converting to a CID involves reversing the hash (to little-endian form), encoding as a dbl-sha2-256 multihash and encoding as a bitcoin-tx multicodec. This process is reversable, see cidToHash.

<a name="BitcoinWitnessCommitment__encode____"></a>

BitcoinWitnessCommitment.encode()

bitcoin-witness-commitment / 0xb2 codec: Encodes an IPLD node representing a Bitcoin witness commitment object into byte form.

The object is expected to be in the form {witnessMerkleRoot:CID, nonce:Uint8Array} where the witnessMerkleRoot may be null.

<a name="BitcoinWitnessCommitment__decode____"></a>

BitcoinWitnessCommitment.decode()

bitcoin-witness-commitment / 0xb2 codec: Decodes a bytes form of a Bitcoin witness commitment into an IPLD node representation. .

The returned object will be in the form {witnessMerkleRoot:CID, nonce:Uint8Array} where the witnessMerkleRoot may be null.

<a name="BitcoinWitnessCommitment__name"></a>

BitcoinWitnessCommitment.name

bitcoin-witness-commitment / 0xb2 codec: the codec name

<a name="BitcoinWitnessCommitment__code"></a>

BitcoinWitnessCommitment.code

bitcoin-witness-commitment / 0xb2 codec: the codec code

<a name="DblSha2256__name"></a>

DblSha2256.name

dbl-sha2-256 / 0x56 multihash: the multihash name

<a name="DblSha2256__code"></a>

DblSha2256.code

dbl-sha2-256 / 0x56 multihash: the multihash code

<a name="DblSha2256__encode____"></a>

DblSha2256.encode()

dbl-sha2-256 / 0x56 multihash: Encode bytes using the multihash algorithm, creating raw 32-byte digest without multihash prefix.

<a name="DblSha2256__digest____"></a>

DblSha2256.digest()

dbl-sha2-256 / 0x56 multihash: Encode bytes using the multihash algorithm, creating multihash Digest (i.e. with multihash prefix).

License

Licensed under either of

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.