A BIP 174 PSBT may contain an extended key for deriving input and output addresses. This document proposes an additional field for PSBTs to represent arbitrary BIP 380 output script descriptors.
To support transfer of output descriptors outside signing flows, the proposal makes the unsigned transaction optional.
I don’t think PSBT is the right way to be doing this. Descriptors are not necessary in PSBT, and relaxing the invariant that a PSBT represents a transaction (by allowing a PSBT to include no transaction data) would break many parsers and also just is antithetical to PSBT. It’s not a general purpose format for sending data around - you could use protobuf if you wanted that.
If the goal is to have a machine parsable representation of descriptors, then by all means, do that. But it doesn’t need to (nor do I think it should) interact with PSBT, other than having a different header that identifies it.
It’s also unnecessary to have a descriptor in a PSBT. A PSBT can contain all of the data to derive it from the scriptPubKey at a later time. If an updater has the descriptor in order to put it in the PSBT, then it can also put the rest of the data in the PSBT so that the descriptor can be inferred. I just don’t see how this proposal is at all useful.
Also, descriptors are a textual format, and encoding text in binary is just not very efficient. There are better ways to do that if you really wanted to.
I don’t think PSBT is the right way to be doing this. Descriptors are not necessary in PSBT, and relaxing the invariant that a PSBT represents a transaction (by allowing a PSBT to include no transaction data) would break many parsers and also just is antithetical to PSBT. It’s not a general purpose format for sending data around - you could use protobuf if you wanted that.
If the goal is to have a machine parsable representation of descriptors, then by all means, do that. But it doesn’t need to (nor do I think it should) interact with PSBT, other than having a different header that identifies it.
FWIW, the first draft was indeed PSBT with a different header: https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2023-November/022184.html. https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2023-November/022186.html suggested we add descriptors to PSBT proper, which seemed like a good idea.
Would you support an alternative BIP that changed the header to make it intentionally different from PSBT files?
It’s also unnecessary to have a descriptor in a PSBT. A PSBT can contain all of the data to derive it from the scriptPubKey at a later time. If an updater has the descriptor in order to put it in the PSBT, then it can also put the rest of the data in the PSBT so that the descriptor can be inferred.
How can the scriptPubKey infer a descriptor that contains, say, a key expression that ends in ‘/*’?
I just don’t see how this proposal is at all useful.
The point of the BIP is to transfer descriptors between devices, in particular between a coordinator and (resource constrained) signing devices. It can be viewed as a codec for wallet policies.
Today, there exists a plethora of formats for exchanging descriptors, all with downsides:
This proposal addresses them all:
Also, descriptors are a textual format, and encoding text in binary is just not very efficient. There are better ways to do that if you really wanted to.
We believe it’s hopeless to keep a binary representation of output descriptors up to date with the moving target that is textual bip-380 descriptors (BCR-2020-010 attempted but failed). This BIP (along with wallet policies) address the worst offender by encoding extended keys efficiently.
Would you support an alternative BIP that changed the header to make it intentionally different from PSBT files?
That would be fine with me.
How can the
scriptPubKeyinfer a descriptor that contains, say, a key expression that ends in ‘/*’?
Although /* cannot be directly inferred, you can still make an educated guess. It only affects the ends of derivation paths from xpubs, so the last derivation index of a key expression with an xpub could just be replaced with /*. Although descriptors allow for xpubs without a /*, it seems unlikely to me that that would actually be used in practice.
But I don’t understand why you’d need to have the parent descriptor at all. You’ll have enough key origin information to derive any private keys and be able to sign.
BIP 174 PSBTs and Extended Keys: PSBTs, specified in BIP 174, are a format for partially signed Bitcoin transactions, enabling offline signing and multi-party approval workflows. These transactions may contain extended keys for deriving input and output addresses. Extended keys allow for hierarchical deterministic (HD) wallets, where multiple addresses can be derived from a single master key.
Introduction of Output Script Descriptors: The proposal suggests introducing an additional field in PSBTs to represent arbitrary BIP 380 output script descriptors. Output script descriptors, specified in BIP 380, provide a concise way to describe various types of output scripts. This addition would enhance the flexibility and interoperability of PSBTs, allowing for more complex transaction scripts.
Optional Unsigned Transaction: Traditionally, PSBTs include the unsigned transaction itself. However, this proposal suggests making the unsigned transaction optional. This change would allow for the transfer of output descriptors outside of the signing process, potentially simplifying certain workflows or reducing data redundancy.
But I don’t understand why you’d need to have the parent descriptor at all. You’ll have enough key origin information to derive any private keys and be able to sign.
By example in the current ledger miniscript signing flow, the hardware device produce a Proof of Registration (PoR) against the parent descriptor that is stored by the softwarewallet (in order to keep stateless) the first time the descriptor is checked by user on signer side, then every time the software wallet send a psbt to sign to ledger device, it should also supply also the parent descriptor and PoR.
we previously discuss about this here
Hardware signing devices need knowledge of the full descriptor/wallet policy in order to:
(The second could perhaps be considered a strengthening of the traditional guarantees of hardware signers, not sure if it was ever formalized before wallet policies; I think it’s essential in practice for anything that is not single-user)
While it’s true that PSBTs today have enough info to sign, they do not have enough info to do it securely - the descriptor is also needed. Therefore, I agree that it would be a great improvement to be able to pass this info via PSBTs; currently, the Ledger app’s signing flow is sign(PSBT, wallet_policy), and quite some work in the app goes into figuring out change/address_index for each input and change output based on the derivations in the PSBT.
However, I think that’s a separate discussion, and it’s unclear that recycling PSBTs for a purpose other than representing transactions brings any benefit over than directly designing a space-efficient encoding specifically for descriptors or wallet policies ā if the <30% space saving that can be obtained with a re-encoding is deemed important in practice.
Thanks for the prod, @jonatack . I’ve updated the proposal so it’s no longer a PSBT extension but a separate format merely based on PSBT key-value maps.
I’d like to add proof-of-registration (PoR), but I’m not sure how it’s best done. There’s some discussion at https://github.com/wizardsardine/liana/issues/539#issuecomment-1877372827, where @bigspider suggests a HMAC scheme and in a later post @pythcoiner suggest that the format of PoR field should be vendor defined. I’m still of the position that to be maximally useful and interoperable, the PoR field should have a defined format and be a signature, not a HMAC.
I’d like to add proof-of-registration (PoR), but I’m not sure how it’s best done. There’s some discussion at wizardsardine/liana#539 (comment), where @bigspider suggests a HMAC scheme and in a later post @pythcoiner suggest that the format of PoR field should be vendor defined. I’m still of the position that to be maximally useful and interoperable, the PoR field should have a defined format and be a signature, not a HMAC.
As i already said in previous discussion, i do not have strong opinion about wether the PoR should be standardized or not, but i do not think it should be standardized in this BIP.
And anyway if i get it well both sheme (HMAC vs Signature) will be 32 bytes of data?
it should be interesting to have insight from other signing devices teams.
cc @benma @scgbckbone @stepansnigirev @stepansnigirev @JamieDriver
Also @kdmukai. Maybe others?
However, I think that’s a separate discussion, and it’s unclear that recycling PSBTs for a purpose other than representing transactions brings any benefit over than directly designing a space-efficient encoding specifically for descriptors or wallet policies ā if the <30% space saving that can be obtained with a re-encoding is deemed important in practice.
I want to point out that while saving space is important to us, the ability to add metadata and eventually proof-of-registration is the more interesting feature in general.
I am in agreement with @bigspider’s comment above.
BitBox02 libraries have functions like sign_psbt(psbt, wallet_policy) (example), and the policy/descriptor is required for anything but simple single-sigs.
It would be helpful if the way the policy is described and transferred to signers was standardized so apps don’t have to implement different ways to interface with different signers.
PSBT seems like the obvious location to put this information. Another format that contains both the PSBT and the policy, which is interoperable with all software, seems difficult to achieve and impractical.
Given
Perhaps it’s feasible to keep the formats separate, but concatenate them at the transport layer (QR code, files), in a backwards compatible way? Say, append the decriptor at the end of the PSBT, where devices without knowledge of descriptors may parse the PSBT and ignore the rest?
0@@ -0,0 +1,139 @@
1+<pre>
2+ BIP: ?
3+ Layer: Applications
4+ Title: Binary Output Descriptors
5+ Author: SeedHammer <team@seedhammer.com>
6+ License: BSD-2-Clause
The preamble is missing a few mandatory headers:
0 BIP: ?
1 Layer: Applications
2 Title: Binary Output Descriptors
3 Author: SeedHammer <team@seedhammer.com>
4 Comments-URI: https://github.com/bitcoin/bips/wiki/Comments:BIP-seedhammer-binary-output-descriptors
5 Status: Draft
6 Type: Standards Track
7 Created: YYYY-MM-DD
8 License: BSD-2-Clause
I have only lightly reviewed this document.
It sounds to me that there is still some discussion what solution is exactly to be pursued for this document. Iām going to change this to a draft PR for the moment, please set it ready to merge when the proposal is a bit more mature.
Please note that you will need a Backwards Compatibility section, and without going into the content in detail, it seems to me that the Rationale section could be a bit more extensive.
Thanks, Murch. I’ve added the mandatory headers, added a compatibility section, and expanded the rationale section.
It seems to me that the main source of contention is whether the format should be separate or part of PSBT. While convenient to extend PSBT, it’s probably best to separate the format if for nothing else than descriptors are useful outside signing flows.
Proof of registration can wait for a future extension BIP, as suggested by @pythcoiner.
Thanks, Murch. I’ve added the mandatory headers, added a compatibility section, and expanded the rationale section.
It seems to me that the main source of contention is whether the format should be separate or part of PSBT. While convenient to extend PSBT, it’s probably best to separate the format if for nothing else than descriptors are useful outside signing flows.
Proof of registration can wait for a future extension BIP, as suggested by @pythcoiner.
To be more accurate, i think how is processed the PoR should de defined in a separate BIP, but having an optional key-value pair defined in this BIP should be useful imho.
Thanks, Murch. I’ve added the mandatory headers, added a compatibility section, and expanded the rationale section. It seems to me that the main source of contention is whether the format should be separate or part of PSBT. While convenient to extend PSBT, it’s probably best to separate the format if for nothing else than descriptors are useful outside signing flows. Proof of registration can wait for a future extension BIP, as suggested by @pythcoiner.
To be more accurate, i think
howis processed the PoR should de defined in a separate BIP, but having anoptionalkey-value pair defined in this BIP should be useful imho.
Good point. Done.
I’m very much PRO descriptors directly IN PSBTs. Even tho I understand @achow101 comments.
Regardless of the format here (which i haven’t studied) it is useful to have descriptor (or at least policy) in PSBT. Example from Coldcard is when you want to have multiple miniscripts registered on device that have identical keys in miniscript but policy/script is different. Or same keys same policy but order of keys in policy is different. Here you just cannot infer solely from PSBT which wallet to use because keys match for all wallets…
why not just use PSBT_GLOBAL_PROPRIETARY key and send descriptor in there?
I’m very much PRO descriptors directly IN PSBTs. Even tho I understand @achow101 comments.
Descriptors in PSBTs are useful, but descriptors are also useful outside PSBTs: transferring descriptors between wallets, (long term) backups. It would be unfortunate to specify a descriptor format that only solved the signing use-cases.
why not just use
PSBT_GLOBAL_PROPRIETARYkey and send descriptor in there?
That would hijack PSBT_GLOBAL_PROPRIETARY, leaving it no longer available for vendor-specific uses.
26+===Motivation===
27+
28+A BIP 380 output descriptor is a textual representation of a set of output
29+scripts, such that Bitcoin wallets may agree on the scripts and addresses
30+to provide the user. However, a descriptor string by itself is not ideal for
31+transferring between wallets: it lacks a machine recognizable header, cannot
0transferring between wallets: it lacks a machine-recognizable header, cannot
30+to provide the user. However, a descriptor string by itself is not ideal for
31+transferring between wallets: it lacks a machine recognizable header, cannot
32+represent metadata such as name and birth block, and its use of base58 for
33+extended keys is inefficient.
34+
35+BIP 174 gives us a self-describing file format, metadata as well as a compact,
0BIP 174 gives us a self-describing file format, metadata, and a compact,
31+transferring between wallets: it lacks a machine recognizable header, cannot
32+represent metadata such as name and birth block, and its use of base58 for
33+extended keys is inefficient.
34+
35+BIP 174 gives us a self-describing file format, metadata as well as a compact,
36+binary representation of keys. Assuming most wallets already implements the PSBT
0binary representation of keys. Assuming most wallets already implement the PSBT
40+are useful outside of signing flows (backup, initializing wallet
41+software).</ref>
42+<ref> '''Why not use the older Blockchain Commons BCR-2020-010 format?'''
43+The format was [[https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-010-output-desc.md#deprecated-superseded-by-version-3-output-descriptors|recently deprecated]],
44+because its use of reserved CBOR tags.</ref>
45+<ref>'''Why not use the new Blockchain Commons BCR-2023-010 format?'''
0<ref>'''Why not use the new Blockchain Commons BCR-2023-010 format?'''.
39+The PSBT format is not a general purpose container format, and descriptors
40+are useful outside of signing flows (backup, initializing wallet
41+software).</ref>
42+<ref> '''Why not use the older Blockchain Commons BCR-2020-010 format?'''
43+The format was [[https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-010-output-desc.md#deprecated-superseded-by-version-3-output-descriptors|recently deprecated]],
44+because its use of reserved CBOR tags.</ref>
0due to its use of reserved CBOR tags.</ref>
or “because of”
34+
35+BIP 174 gives us a self-describing file format, metadata as well as a compact,
36+binary representation of keys. Assuming most wallets already implements the PSBT
37+format, the implementation overhead of this BIP is expected to be low
38+<ref> '''Why not extend BIP 174?'''
39+The PSBT format is not a general purpose container format, and descriptors
0The PSBT format is not a general-purpose container format, and descriptors
50+In particular, we believe BCR-2023-010 would have faced opposition
51+in the BIP process because it is based on the [[https://cbor.io/spec.html|CBOR encoding]].
52+CBOR is designed for generality and compactness and is therefore significantly
53+more complex than the PSBT encoding. In contrast, the PSBT key-value maps are
54+supported by all wallet software that interact with PSBT files, are easier to
55+review and fit in embedded devices.
0review, and they fit in embedded devices.
52+CBOR is designed for generality and compactness and is therefore significantly
53+more complex than the PSBT encoding. In contrast, the PSBT key-value maps are
54+supported by all wallet software that interact with PSBT files, are easier to
55+review and fit in embedded devices.
56+
57+Release in late 2023, BCR-2023-010 doesn't event have the advantage of widespread
0Released in late 2023, BCR-2023-010 doesn't even have the advantage of widespread
53+more complex than the PSBT encoding. In contrast, the PSBT key-value maps are
54+supported by all wallet software that interact with PSBT files, are easier to
55+review and fit in embedded devices.
56+
57+Release in late 2023, BCR-2023-010 doesn't event have the advantage of widespread
58+support.</ref>.
0support at the time of this writing.</ref>.
58+support.</ref>.
59+
60+==Specification==
61+
62+The Binary Output Descriptor (BOD) format consists of a fixed header, a
63+key-value map describing the output descriptor and its metadata followed by a
85+| <tt><compact size uint birth block><bytes></tt>
86+| The earliest block height that may contain transactions for the descriptor, optionally followed by the UTF-8 encoded name of the descriptor.
87+| <tt><bytes descriptor></tt>
88+| The output descriptor in BIP 380 format without inline keys<ref>''Why not encode the descriptor in binary?'''
89+The BIP 380 descriptor language is complicated and expanding and we believe
90+the efforts of designing a parallel binary encoding does not outweigh the
0the effort of designing a parallel binary encoding does not outweigh the
(This sentence could be more clearly written, as well.)
88+| The output descriptor in BIP 380 format without inline keys<ref>''Why not encode the descriptor in binary?'''
89+The BIP 380 descriptor language is complicated and expanding and we believe
90+the efforts of designing a parallel binary encoding does not outweigh the
91+space savings.
92+
93+The major source of bloat, base58 encoded keys, are binary encoded for compactness and
0The major source of bloat, base58-encoded keys, are binary encoded for compactness and
84+| <tt>BOD_GLOBAL_OUTPUT_DESCRIPTOR = 0x00</tt>
85+| <tt><compact size uint birth block><bytes></tt>
86+| The earliest block height that may contain transactions for the descriptor, optionally followed by the UTF-8 encoded name of the descriptor.
87+| <tt><bytes descriptor></tt>
88+| The output descriptor in BIP 380 format without inline keys<ref>''Why not encode the descriptor in binary?'''
89+The BIP 380 descriptor language is complicated and expanding and we believe
0The BIP 380 descriptor language is complicated and expanding, and we believe
95+.</ref>
96+|-
97+| Proprietary Use Type
98+| <tt>BOD_GLOBAL_PROPRIETARY = 0xFC</tt>
99+| <tt><compact size uint identifier length> <bytes identifier> <compact size uint subtype> <bytes subkeydata></tt>
100+| Compact size unsigned integer of the length of the identifier, followed by identifier prefix, followed by a compact size unsigned integer subtype, followed by the key data itself.
Suggest using an article for each item or for none.
0| A compact size unsigned integer of the length of the identifier, followed by an identifier prefix, followed by a compact size unsigned integer subtype, followed by the key data itself.
103+|}
104+
105+It is an error to omit the BOD_GLOBAL_OUTPUT_DESCRIPTOR entry.
106+
107+All key expressions in the BOD_GLOBAL_OUTPUT_DESCRIPTOR descriptor string must be
108+specified as references on the form <tt>@<index></tt> where <tt>index</tt> is
IIUC
0specified as references in the form of <tt>@<index></tt> where <tt>index</tt> is
130+! <tt><valuedata></tt> Description
131+|-
132+| Extended Public Key
133+| <tt>BOD_KEY_XPUB = 0x00</tt>
134+| <tt><bytes xpub></tt>
135+| The 78 byte serialized extended public key as defined by BIP 32.
0| The 78-byte serialized extended public key, as defined by BIP 32.
132+| Extended Public Key
133+| <tt>BOD_KEY_XPUB = 0x00</tt>
134+| <tt><bytes xpub></tt>
135+| The 78 byte serialized extended public key as defined by BIP 32.
136+| <tt><4 byte fingerprint> <32-bit little endian uint path element>*</tt>
137+| The master key fingerprint as defined by BIP 32 concatenated with the derivation path of the public key. The derivation path is represented as 32-bit little endian unsigned integer indexes concatenated with each other. The number of 32 bit unsigned integer indexes must match the depth provided in the extended public key.
0| The master key fingerprint, as defined by BIP 32, concatenated with the derivation path of the public key. The derivation path is represented as 32-bit little endian unsigned integer indexes concatenated with each other. The number of 32-bit unsigned integer indexes must match the depth provided in the extended public key.
137+| The master key fingerprint as defined by BIP 32 concatenated with the derivation path of the public key. The derivation path is represented as 32-bit little endian unsigned integer indexes concatenated with each other. The number of 32 bit unsigned integer indexes must match the depth provided in the extended public key.
138+|-
139+| Proprietary Use Type
140+| <tt>BOD_KEY_PROPRIETARY = 0xFC</tt>
141+| <tt><compact size uint identifier length> <bytes identifier> <compact size uint subtype> <bytes subkeydata></tt>
142+| Compact size unsigned integer of the length of the identifier, followed by identifier prefix, followed by a compact size unsigned integer subtype, followed by the key data itself.
idem
0| A compact size unsigned integer of the length of the identifier, followed by an identifier prefix, followed by a compact size unsigned integer subtype, followed by the key data itself.
151+A descriptor with a key reference out of bounds.
152+ Descriptor: wpkh(@0/*)
153+ Hex encoded BOD: 70736274ff0207000a77706b682840302f2a29000000
154+
155+A descriptor with an invalid UTF-8 name.
156+ Hex encoded BOD: 70736274ff05070061c57a0a77706b682840302f2a2953010488b21e041c0ae906800000025afed56d755c088320ec9bc6acd84d33737b580083759e0a0ff8f26e429e0b77028342f5f7773f6fab374e1c2d3ccdba26bc0933fc4f63828b662b4357e4cc3791bec0fbd814c5d8729748000080000000800000008002000080000000
0 Hex-encoded BOD: 70736274ff05070061c57a0a77706b682840302f2a2953010488b21e041c0ae906800000025afed56d755c088320ec9bc6acd84d33737b580083759e0a0ff8f26e429e0b77028342f5f7773f6fab374e1c2d3ccdba26bc0933fc4f63828b662b4357e4cc3791bec0fbd814c5d8729748000080000000800000008002000080000000
154+
155+A descriptor with an invalid UTF-8 name.
156+ Hex encoded BOD: 70736274ff05070061c57a0a77706b682840302f2a2953010488b21e041c0ae906800000025afed56d755c088320ec9bc6acd84d33737b580083759e0a0ff8f26e429e0b77028342f5f7773f6fab374e1c2d3ccdba26bc0933fc4f63828b662b4357e4cc3791bec0fbd814c5d8729748000080000000800000008002000080000000
157+
158+A descriptor with an inline key.
159+ Hex encoded BOD: 70736274ff0207008e77706b68285b64633536373237362f3438682f30682f30682f32685d7870756236446959726652774e6e6a655834764873574d616a4a56464b726245456e753867415739764475517a675457457345484531367347576558585556314c42575145317943546d657072534e63715a3357373468715664674462745948557633654d3457325445556870616e2f2a29000000
0 Hex-encoded BOD: 70736274ff0207008e77706b68285b64633536373237362f3438682f30682f30682f32685d7870756236446959726652774e6e6a655834764873574d616a4a56464b726245456e753867415739764475517a675457457345484531367347576558585556314c42575145317943546d657072534e63715a3357373468715664674462745948557633654d3457325445556870616e2f2a29000000
165+ Name: Satoshi's Stash
166+ Birth block: 123456789012345
167+ Key 0: [dc567276/48h/0h/0h/2h]xpub6DiYrfRwNnjeX4vHsWMajJVFKrbEEnu8gAW9vDuQzgTWEsEHE16sGWeXXUV1LBWQE1yCTmeprSNcqZ3W74hqVdgDbtYHUv3eM4W2TEUhpan
168+ Key 1: [f245ae38/48h/0h/0h/2h]xpub6DnT4E1fT8VxuAZW29avMjr5i99aYTHBp9d7fiLnpL5t4JEprQqPMbTw7k7rh5tZZ2F5g8PJpssqrZoebzBChaiJrmEvWwUTEMAbHsY39Ge
169+ Key 2: [c5d87297/48h/0h/0h/2h]xpub6DjrnfAyuonMaboEb3ZQZzhQ2ZEgaKV2r64BFmqymZqJqviLTe1JzMr2X2RfQF892RH7MyYUbcy77R7pPu1P71xoj8cDUMNhAMGYzKR4noZ
170+ Hex encoded BOD: 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
0 Hex-encoded BOD: 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
173+
174+<references/>
175+
176+==Compatibility==
177+
178+This is a new format and as such have no campatibility burden.
0This is a new format and as such has no compatibility burden.
Suggestions by @jonatack.
Co-authored-by: Jon Atack <jon@atack.com>
Suggestions by @jonatack.
