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Support for BIP49 YPUB/UPUB #927

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plasticlobster
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The only thing missing from bitcoinjs-lib to support BIP49 is the network type designator. This simple change allows the HD wallet to support BIP49 YPUB's (or testnet UPUB's). This allows for the import of pure segwit HD wallets.

See also: https://github.com/bitcoin/bips/blob/master/bip-0049.mediawiki

Understanding that BIP49 is draft, you may reject this change, but I've made this change for a project and figured submitting a PR would be an appropriate offer to allow you to implement this simple functionality.

@dcousens
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From reading that BIP, I don't see the network constants you've specified...

Instead, the only difference I saw was that the purpose constant was 49 not 44?

To derive a public key from the root account, this BIP uses the same account-structure as defined in BIP 44, but only uses a different purpose value to indicate the different transaction serialization method.

@plasticlobster
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@dcousens

My address generation happens outside of bitcoinjs-lib, and I'm not sure if there are more implications to fully supporting an implementation of BIP49 as a result.

The use case was for an electrum wallet. See:
http://docs.electrum.org/en/latest/seedphrase.html#list-of-reserved-numbers
and
https://github.com/spesmilo/electrum/blob/0a648e2b1cdb7852d80c0626c62984ef01c1c7e9/lib/bitcoin.py#L50

The usage of these constants (which translate to ypub and upub) allow for auto-detection of a bip49-style wallet. When using a bip32-style xpub, it's impossible to determine whether the wallet is bip32 or bip49. While the constants do not appear in a BIP, they are the constants currently in use by wallet providers like electrum.

@dcousens
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dcousens commented Nov 28, 2017

Is this related to #934 ?

@@ -64,7 +64,9 @@ HDNode.fromBase58 = function (string, networks) {
if (Array.isArray(networks)) {
network = networks.filter(function (x) {
return version === x.bip32.private ||
version === x.bip32.public
version === x.bip32.public ||
version === x.bip49.private ||
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@afk11 afk11 Dec 15, 2017

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I think these semantics should be opt-in. Imagine someone supported Bitcoin Cash, and imported keys. There's not currently a bitcoin-cash network in the library, so they're using the bitcoin network for that. Imagine they didn't read the release notes, and allowed users to import a P2SH(P2WPKH) address, and funded that on Bitcoin Cash.. They're unspendable without talking to a miner.

I think this feature should be opt in, so a new function bip44TypefromBase58 or something that forces developers to think about what they are doing.

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@afk11 I don't understand, what about these new BIP49 constants would trap users into creating unspendable addresses?

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@dcousens dcousens Jan 17, 2018

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Isn't the risk that any P2SH(P2WPKH) scripts are unspendable by BCash nodes?
Nothing to do with the BIP49 constants?

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Applications might accept stuff they shouldn't when forks like bitcoin cash happen, and developers start using bitcoin.networks.bitcoin as a bitcoin cash network. It's mostly that the feature should only be used via specialized encoding/decoding/factory functions. That way, developers have to consider the difference between xpub only, and the format that uses different scripts.

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https://github.com/plasticlobster/bitcoinjs-lib/blob/8f39b516946805c6b4640d1df0fdd33a0ebedba7/src/hdnode.js#L129
This should be updated to use script type

Should also be opt in, and not usable by people who expect fromBase58 to only parse normal BIP32 keys.

@afk11
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afk11 commented Dec 15, 2017

In general I think the proposal has its merits, it's nice to support what some of the major wallets are doing. I have some comments on the PR and proposal in general.

Generally, concept ACK once it's opt in.

Worth mentioning that the situation with these new prefixes isn't perfect, since some prefixes can have two script types. The specification just seems to be the ML post and electrum website, so it's not clear what the official spec actually is outside of specific prefixes.

I think we can introduce this as limited support for such versioned BIP32 wallets, and see what other prefixes people request. Maybe the config parameters could go into bip32ScriptVersions, as a new property on the network? Minor nit though

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LGTM, waiting on @afk11

@dcousens
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dcousens commented Jan 17, 2018

Shouldn't getAddress be changed too? (even if it is being removed in 4.0.0)

@dcousens dcousens modified the milestones: 4.0.0, 3.4.0 Jan 17, 2018
@dcousens
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@dabura667 @junderw where does zpub fit into this?

@dabura667
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@dcousens Honestly... I think maybe this is a little bit early.

I would really like to see a BIP from @ecdsa before we merge this.

Also, I think this is insufficient.

Electrum also has extra version bytes for WIF private keys. We should probably include those if we include this.

zpub/prv are for native P2WPKH.

Currently, ECPair and HDNode have a network attribute which refers to a network in networks.

I think they should also have an attribute for "scriptType" which will tell us what to use when using toWIF or toBase58Check respectively. So we can look at the scriptType, and use that to guide us as to what to fetch from the network object.

I also dislike calling this bip49... perhaps keep all the legacy network structure and add a new key:

ie.

  bitcoin: {
    messagePrefix: '\x18Bitcoin Signed Message:\n',
    bech32: 'bc',
    bip32: {
      public: 0x0488b21e,
      private: 0x0488ade4
    },
    pubKeyHash: 0x00,
    scriptHash: 0x05,
    wif: 0x80,
    versionBytes: {
      ECPair: {
        'P2PKH': {
          wif: 0x80
        },
        'P2SH(P2WPKH)': {
          wif: 0x82
        },
        'P2WPKH': {
          wif: 0x81
        }
      },
      HDNode: {
        'P2PKH': {
          public: 0x0488b21e,
          private: 0x0488ade4
        },
        'P2SH(P2WPKH)': {
          public: 0x049d7cb2,
          private: 0x049d7878
        },
        'P2WPKH': {
          public: 0x04b24746,
          private: 0x04b2430c
        }
      }
    }
  },

(WIF values weren't in wiki, but they are in the bitcoin.py.
https://github.com/spesmilo/electrum/blob/0a648e2b1cdb7852d80c0626c62984ef01c1c7e9/lib/bitcoin.py#L483
The function for encoding WIF keys is right below it and you see they are adding those numbers to 128, which is essentially ORing them.)

@dcousens
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What a mess.

@junderw
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junderw commented Jan 18, 2018

Yup. It is.

Big old mess.

But I have been thinking for a while that now we have different ways to use private keys, we need a state similar to compressed that can store the script type. The way this is represented when exported or imported can be added later when BIPs are written.

What do you think? @dcousens

@dcousens
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dcousens commented Jan 18, 2018

@junderw it feels like the version bytes are becoming useless as network information, and instead, acting as flags for other meta information.

Maybe we should support non-strict fromBase58 decoding? Sigh.

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dcousens commented Jan 18, 2018

Can we simply tell these muppets to please stop abusing the BIP32 standard and instead write a BIP that stores this information somewhere else?

@junderw
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junderw commented Jan 18, 2018

IMO we have bech32, why not use it? lol.

@junderw
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junderw commented Jan 18, 2018

hrp could be p2shp2wpkh or something

@junderw
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junderw commented Jan 18, 2018

xpubp2shp2wpkh1sdfouofgsdfijo9df8ehosf8feojosihfhe8fh

etc etc

@dcousens
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dcousens commented Jan 18, 2018

@junderw I have an idea, lets write a BIP that captures the path information AND the address type(s).

https://imgs.xkcd.com/comics/standards.png

(semi serious, it might take less time than writing sane APIs for this mess)

@junderw
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junderw commented Jan 18, 2018

While that comic is true.

Character encoding has a clear winner.

If you don't use UTF-8 you are wrong.

@dcousens
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dcousens commented Jan 18, 2018

@junderw would ROOT_NODE | (PATH | ADDRESS_TYPE | IS_PRIMARY | IS_CHANGE | GAP_LIMIT)+ suit most of these cases?
I guess you probably want some extension possibilities for things like multisig...

Why is this necessary anyway? Who is actually passing around these base58 strings rather than a mnemonic?

@ecdsa
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ecdsa commented Jan 18, 2018

@dabura667 we will submit a BIP

@dcousens
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@ecdsa are you open to engaging in a discussion about a more generic standard e.g like the above?

@junderw
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junderw commented Jan 18, 2018

Why is the distinction necessary anyway?

Mainly for xpubs. A lot of people pass around xpubs for watch-only and merchant services.

@dcousens
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dcousens commented Jan 18, 2018

Mainly for xpubs. A lot of people pass around xpubs for watch-only and merchant services.

Everyone read the Security and Implications part of BIP32, right?
Why has this become a thing?

We even have an example of how to take advantage of this weakness in our integration tests.

@ecdsa
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ecdsa commented Jan 18, 2018

@ecdsa are you open to engaging in a discussion about a more generic standard e.g like the above?

can you be more specific?

@junderw
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junderw commented Jan 18, 2018

Why has this become a thing?

Have you ever used Electrum? Electrum made it a thing since before BIP32 was even a thing.

The rationale is that you can't export individual private keys from Electrum, so it's not a problem. (iirc)

@mautematico
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mautematico commented Feb 4, 2018

Why is this necessary anyway? Who is actually passing around these base58 strings rather than a mnemonic?

To create watch-only wallets for internal (but secure) use; just like I am trying to do right now.

The rationale is that you can't export individual private keys from Electrum, so it's not a problem. (iirc)
Yes, you can export individual private keys from electrum.

Wallet >> Private Keys >> Export

@dabura667
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watch-only wallets for internal (but secure) use

Watch-only wallets are easy to hack: Just replace the xpub with a hacker's xpub. Now everyone will send money to the hacker and not you.

@mautematico
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mautematico commented Feb 4, 2018

Watch-only wallets are easy to hack: Just replace the xpub with a hacker's xpub. Now everyone will send money to the hacker and not you.

That is pointless; exactly the same can be done regardless if you are using xpub or not. So no "xpub hack" here.

@dabura667
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This PR is not complete, that’s why it’s not working.

@clarkmoody
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We also have the SLIP-32 proposal out there, which encodes the derivation path within the serialized xpub data payload.

@plasticlobster
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@mautematico You're right. getAddress would need modification to get the proper address, but you can do it as follows:

const Bitcoin = require('bitcoinjs-lib');

Bitcoin.address.fromOutputScript(
  Bitcoin.script.scriptHash.output.encode(
    Bitcoin.crypto.hash160(
      Bitcoin.script.witnessPubKeyHash.output.encode(
        Bitcoin.crypto.hash160(
          Bitcoin.HDNode.fromBase58('ypub6XMTwf6NSvfzYYgVgdNWRNfMTiQt4rSjZbEk8qoCnBGhUD2rsgZ2A8pexgzaGLKgySZxqxrctDpAVU8QtfxqfX8QUAhtFmGFUFx9B51TVg8', Bitcoin.networks.bitcoin)
          .derive(0)
          .derive(27)
          .getPublicKeyBuffer()
        )
      )
    )
  ),
  Bitcoin.networks.bitcoin
)

Obviously a change like this would have to be implemented in getAddress to make this easier, but I don't even want to pretend I understand the coding requirements of this project enough to propose that change.

@dcousens
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dcousens commented Feb 12, 2018

For context on 4.0.0, the above code becomes:

const bitcoin = require('bitcoinjs-lib')
const pubKey = bitcoin.HDNode.fromBase58('ypub6XMTwf6NSvfzYYgVgdNWRNfMTiQt4rSjZbEk8qoCnBGhUD2rsgZ2A8pexgzaGLKgySZxqxrctDpAVU8QtfxqfX8QUAhtFmGFUFx9B51TVg8')
  .derive(0)
  .derive(27)
  .getPublicKeyBuffer()

const { address } = bitcoin.payments.p2sh({
  redeem: bitcoin.payments.p2wpk({
    pubkey: pubKey
  })
})

@dcousens
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ping @afk11

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afk11 commented Mar 3, 2018

I think the PR needs to address generating the scriptPubKey/address for it to be complete, first of all.

It'd really be nice for it to work with the other BIP's that do this custom HD prefix to indicate an address. There's BIP49, and BIP84, each has custom HD prefixes implementing the same logic, which is constructing a HD key capable of producing a P2SH|P2WPKH address, or P2WPKH respectively. Electrum takes this a step further, and defines 5 prefix/scriptTypes for which they do this.

I've been thinking about the missing address generation part of this PR: could we add an optional parameter to the hdkey constructor, a closure accepting a public or private key, and returns a {scriptPubKey:, rs:, ws:, address: } when called? We can add the optional parameter to the generation methods as well. Derivations could pass on the closure to children as well.

hdkey.getAddress could then check if the closure was set, and call it if so. If it wasn't set, just return P2PKH. A default closure of P2PKH could be how we make this work, actually. Maybe we want to add another function to hdkey, that returns {scriptPubKey:, rs:, ws:, address: }, since getAddress exclusively returns the address. This information would be really handy for signing time!

That way, we can inject different kinds of closures to work with all the types that electrum supports (http://docs.electrum.org/en/latest/seedphrase.html):

  • P2PKH (xprv)
  • P2SH|P2PKH (xprv - conflicts)
  • P2SH|P2WPKH (yprv)
  • P2SH|P2WSH|P2PKH (Yprv)
  • P2WPKH (zprv)
  • P2WSH|P2PKH (Zprv)

It'd be nice to support the 5 (or more) serialization formats as well. One issue I have with the PR is that the deserialization will succeed even for people who don't want the feature. It'd be nice if people could control which prefix/scriptTypes are active during a deserialization? Could we find a way to pass in the extra prefixes/scriptTypes/closures for consideration in a call

Maybe the prefixes/scriptTypes could be defined in the network, then a selection of these can be passed into deserialize/serialize methods?

Whew.. this one's been on my mind anyway, overall the feature is nice to have if it's future proof against script-types, and developers need to opt into the behavior somehow!

@clarkmoody
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clarkmoody commented Mar 3, 2018 via email

@afk11
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afk11 commented Mar 4, 2018

I took a quick look at getting getAddress to work, but a mocked getAddress test fails, since keyPair.getAddress was overwritten and now the results aren't identical.

Makes me wonder if keyPair should have getAddress, but anyways. I'll comment the test for now since the addresses will vary going forward!

#1014 - allows 'extra' prefixes to be provided by developers, or allows regular behavior of using the networks bip32 prefix.

@dcousens
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dcousens commented Apr 12, 2018

Related to bitcoin/bips#673 ?
Not HD though...

@liangfenxiaodao
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@mautematico may I have one question?

for this code:

Bitcoin.HDNode.fromBase58('ypub6XMTwf6NSvfzYYgVgdNWRNfMTiQt4rSjZbEk8qoCnBGhUD2rsgZ2A8pexgzaGLKgySZxqxrctDpAVU8QtfxqfX8QUAhtFmGFUFx9B51TVg8', Bitcoin.networks.bitcoin)
    .derive(0)
    .derive(27)
    .getAddress()

I'd like to know what's the meaning of derive(0) and then derive(27), could you please explain a little bit?

Thank you very much.
Jacky.

@mautematico
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@jackylimel sure,

have you read about bip32 derivation paths? They let you generate multiple public-private key pairs from a single initial master public-private pair (ypub & ypriv).

twice .derive(0).derive(0) is the same as .derivePath("m/0/0")

https://bitcoin.stackexchange.com/questions/56561/bip32-derivation-path
http://bip32.org/

@dcousens dcousens removed this from the 3.4.0 milestone May 14, 2018
@Overtorment
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for anyone waiting for ypub support in bitcoinjs, heres a quick workaround I borrowed from #966

    // bitcoinjs does not support ypub yet, so we just convert it from xpub
    const b58 = require('bs58check')
    let data = b58.decode(xpub)
    data = data.slice(4)
    data = Buffer.concat([Buffer.from('049d7cb2','hex'), data])
    return b58.encode(data);

@sneurlax
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sneurlax commented Jul 9, 2018

@Overtorment, thanks for that. This should be the zpub equivalent workaround:

let data = b58.decode(xpub)
data = data.slice(4);
data = Buffer.concat([Buffer.from('04b24746','hex'), data]); // see https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2017-September/014907.html for tenative (non-BIP-official) version bytes
return b58.encode(data);

EDIT: SLIP-0132 is a better source than the email linked above until it's in an actual BIP

@dcousens
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What do I do here?
With the removal of getAddress...

Thoughts?

@dcousens dcousens closed this Jul 23, 2018
@youssefgh
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@dcousens i believe that "YPUB/UPUB" is now a part of BIP49. See Extended Key Version
What do you think ?

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