Master is not stable; it is our development branch, and [only tagged releases may be classified as stable](https://github.com/bitcoinjs/bitcoinjs-lib/tags).
We recommend every user of this library and the [bitcoinjs](https://github.com/bitcoinjs) ecosystem audit and verify any underlying code for its validity and suitability, including reviewing any and all of your project's dependencies.
Mistakes and bugs happen, but with your help in resolving and reporting [issues](https://github.com/bitcoinjs/bitcoinjs-lib/issues), together we can produce open source software that is:
Presently, we do not have any formal documentation other than our [examples](#examples), please [ask for help](https://github.com/bitcoinjs/bitcoinjs-lib/issues/new) if our examples aren't enough to guide you.
**WARNING**: We presently don't provide any tooling to verify that the release on `npm` matches GitHub. As such, you should verify anything downloaded by `npm` against your own verified copy.
When working with private keys, the random number generator is fundamentally one of the most important parts of any software you write.
For random number generation, we *default* to the [`randombytes`](https://github.com/crypto-browserify/randombytes) module, which uses [`window.crypto.getRandomValues`](https://developer.mozilla.org/en-US/docs/Web/API/window.crypto.getRandomValues) in the browser, or Node js' [`crypto.randomBytes`](https://nodejs.org/api/crypto.html#crypto_crypto_randombytes_size_callback), depending on your build system.
Although this default is ~OK, there is no simple way to detect if the underlying RNG provided is good enough, or if it is **catastrophically bad**.
You should always verify this yourself to your own standards.
This library uses [tiny-secp256k1](https://github.com/bitcoinjs/tiny-secp256k1), which uses [RFC6979](https://tools.ietf.org/html/rfc6979) to help prevent `k` re-use and exploitation.
Unfortunately, this isn't a silver bullet.
Often, Javascript itself is working against us by bypassing these counter-measures.
Problems in [`Buffer (UInt8Array)`](https://github.com/feross/buffer), for example, can trivially result in **catastrophic fund loss** without any warning.
It can do this through undermining your random number generation, accidentally producing a [duplicate `k` value](https://www.nilsschneider.net/2013/01/28/recovering-bitcoin-private-keys.html), sending Bitcoin to a malformed output script, or any of a million different ways.
* Don't share BIP32 extended public keys ('xpubs'). [They are a liability](https://bitcoin.stackexchange.com/questions/56916/derivation-of-parent-private-key-from-non-hardened-child), and it only takes 1 misplaced private key (or a buggy implementation!) and you are vulnerable to **catastrophic fund loss**.
* [Don't use `Math.random`](https://security.stackexchange.com/questions/181580/why-is-math-random-not-designed-to-be-cryptographically-secure) - in any way - don't.
* Enforce that users always verify (manually) a freshly-decoded human-readable version of their intended transaction before broadcast.
* Don't *ask* users to generate mnemonics, or 'brain wallets', humans are terrible random number generators.
* Lastly, if you can, use [Typescript](https://www.typescriptlang.org/) or similar.
**NOTE**: We use Node Maintenance LTS features, if you need strict ES5, use [`--transform babelify`](https://github.com/babel/babelify) in conjunction with your `browserify` step (using an [`es2015`](https://babeljs.io/docs/plugins/preset-es2015/) preset).
**WARNING**: iOS devices have [problems](https://github.com/feross/buffer/issues/136), use atleast [buffer@5.0.5](https://github.com/feross/buffer/pull/155) or greater, and enforce the test suites (for `Buffer`, and any other dependency) pass before use.
Type declarations for Typescript [are available](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/0897921174860ec3d5318992d2323b3ae8100a68/types/bitcoinjs-lib) for version `^3.0.0` of the library.
For VSCode (and other editors), it is advised to install the type declarations, as Intellisense uses that information to help you code (autocompletion, static analysis).
**WARNING**: These Typescript definitions are not maintained by the maintainers of this repository, and are instead maintained at [DefinitelyTyped](https://github.com/DefinitelyTyped/DefinitelyTyped).
[Flow-type](https://flowtype.org/) definitions for are available in the [flow-*typed* repository](https://github.com/flowtype/flow-typed/tree/master/definitions/npm/bitcoinjs-lib_v2.x.x) for version `^2.0.0` of the library.
You can [download them directly](https://github.com/flowtype/flow-typed/blob/master/definitions/npm/bitcoinjs-lib_v2.x.x/flow_v0.17.x-/bitcoinjs-lib_v2.x.x.js), or using the flow-typed CLI:
- [Generate a random address](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/addresses.js#L22)
- [Import an address via WIF](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/addresses.js#L40)
- [Generate a 2-of-3 P2SH multisig address](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/addresses.js#L47)
- [Generate a SegWit address](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/addresses.js#L60)
- [Generate a SegWit P2SH address](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/addresses.js#L67)
- [Generate a SegWit 3-of-4 multisig address](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/addresses.js#L76)
- [Generate a SegWit 2-of-2 P2SH multisig address](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/addresses.js#L90)
- [Support the retrieval of transactions for an address (3rd party blockchain)](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/addresses.js#L104)
- [Generate a Testnet address](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/addresses.js#L123)
- [Generate a Litecoin address](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/addresses.js#L133)
- [Create a 1-to-1 Transaction](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/transactions.js#L13)
- [Create a 2-to-2 Transaction](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/transactions.js#L28)
- [Create (and broadcast via 3PBP) a typical Transaction](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/transactions.js#L47)
- [Create (and broadcast via 3PBP) a Transaction with an OP\_RETURN output](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/transactions.js#L83)
- [Create (and broadcast via 3PBP) a Transaction with a 2-of-4 P2SH(multisig) input](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/transactions.js#L105)
- [Create (and broadcast via 3PBP) a Transaction with a SegWit P2SH(P2WPKH) input](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/transactions.js#L143)
- [Create (and broadcast via 3PBP) a Transaction with a SegWit P2WPKH input](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/transactions.js#L174)
- [Create (and broadcast via 3PBP) a Transaction with a SegWit P2PK input](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/transactions.js#L218)
- [Create (and broadcast via 3PBP) a Transaction with a SegWit 3-of-4 P2SH(P2WSH(multisig)) input](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/transactions.js#L263)
- [Verify a Transaction signature](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/transactions.js#L304)
- [Import a BIP32 testnet xpriv and export to WIF](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/bip32.js#L12)
- [Export a BIP32 xpriv, then import it](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/bip32.js#L20)
- [Export a BIP32 xpub](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/bip32.js#L31)
- [Create a BIP32, bitcoin, account 0, external address](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/bip32.js#L40)
- [Create a BIP44, bitcoin, account 0, external address](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/bip32.js#L55)
- [Create a BIP49, bitcoin testnet, account 0, external address](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/bip32.js#L71)
- [Use BIP39 to generate BIP32 addresses](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/bip32.js#L86)
- [Create (and broadcast via 3PBP) a Transaction where Alice can redeem the output after the expiry (in the past)](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/cltv.js#L43)
- [Create (and broadcast via 3PBP) a Transaction where Alice can redeem the output after the expiry (in the future)](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/cltv.js#L88)
- [Create (and broadcast via 3PBP) a Transaction where Alice and Bob can redeem the output at any time](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/cltv.js#L144)
- [Create (but fail to broadcast via 3PBP) a Transaction where Alice attempts to redeem before the expiry](https://github.com/bitcoinjs/bitcoinjs-lib/blob/master/test/integration/cltv.js#L190)
