wallet: derivehdkey RPC to get xpub at arbitrary path - #32784
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The following sections might be updated with supplementary metadata relevant to reviewers and maintainers. Code Coverage & BenchmarksFor details see: https://corecheck.dev/bitcoin/bitcoin/pulls/32784. ReviewsSee the guideline and AI policy for information on the review process.
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If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first. LLM Linter (✨ experimental)Possible typos and grammar issues:
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2026-08-05 08:25:34 |
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In util.h: “@params[in] path” → “@param[in] path” [Doxygen tag typo]
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addressesd -> addresses [extra “d” makes “addresses” misspelled]
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Very nice, Concept ACK. |
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Rebased after #32489. I moved the new |
…tor' into HEAD Resolve the createwalletdescriptor conflict between bitcoin#32784 and bitcoin#32861 by keeping bitcoin#32861's fallback to unused KEY descriptors, but adapting the active descriptor lookup to bitcoin#32784's GetHDPubKeys(HDKeyFilter::Active) API and extracting the xpub from the map key.
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Since #35606 has now merged, we can simplify the fingerprint handling using the new type-safe helpers.
| CExtKey descendant = ext_key; | ||
| KeyOriginInfo origin; | ||
| const CKeyID id = ext_key.key.GetPubKey().GetID(); | ||
| std::copy(id.begin(), id.begin() + sizeof(origin.fingerprint), origin.fingerprint); |
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| KeyOriginInfo expected_origin; | ||
| const CKeyID id{master.key.GetPubKey().GetID()}; | ||
| std::copy(id.begin(), id.begin() + sizeof(expected_origin.fingerprint), expected_origin.fingerprint); |
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Ditto. We can use
expected_origin.fingerprint = master.id_key_fingerprint();| #include <test/util/setup_common.h> | ||
| #include <util/strencodings.h> | ||
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| #include <algorithm> |
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This can be dropped if we use the id_key_fingerprint() suggestion
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| UniValue res{UniValue::VOBJ}; | ||
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| std::string fingerprint{HexStr(std::span<unsigned char>(child->second.fingerprint, child->second.fingerprint + 4))}; |
Co-authored-by: w0xlt <94266259+w0xlt@users.noreply.github.com>
ParseHDKeypath() lives in util/bip32, so its unit test belongs in bip32_tests rather than psbt_wallet_tests. Pure move, no changes to the test itself; subsequent commits extend it in its new home.
ParseHDKeypath() parsed each path element with ToIntegral<uint32_t>, so a bare decimal >= 2^31 (e.g. "m/2147483648" == 0x80000000) was silently treated as "m/0h". This commit rejects such overflow instead.
GetHDPubKeys() centralizes the descriptor xpub lookup used by gethdkeys and createwalletdescriptor, and by the derivehdkey RPC added in a later commit. The HDKeyFilter argument serves gethdkeys' active_only mode (Active vs All) and createwalletdescriptor's active descriptor selection. No behavior change, except the dynamic_cast now uses Assert() instead of gethdkeys' CHECK_NONFATAL, since it is not a recoverable input.
Reconstruct a descriptor's extended private key from its xpub by looking up the corresponding private key. This is the extended-key analog of GetKey(). It is used here to simplify gethdkeys, and again by the derivehdkey RPC introduced in a later commit.
Add an UnusedKey filter to GetHDPubKeys() so the new RPC can prefer unused(KEY) descriptors before falling back to active descriptors. Co-authored-by: w0xlt <94266259+w0xlt@users.noreply.github.com>
Use derivehdkey instead of extracting each participant xpub (and derivation info) from the listdescriptors output. Additionally use the new <0;1> descriptor syntax. Finally this commits adds a few debug log lines, and expand the explanation for why we use m/44h/1h/0h.
Use derivehdkey instead of extracting each participant xpub from the listdescriptors output. Additionally use the new <0;1> descriptor syntax.
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Rebased and switched to #35606 |
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🚧 At least one of the CI tasks failed. HintsTry to run the tests locally, according to the documentation. However, a CI failure may still
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The ci failure is unrelated, you can just add wno-error=... to the ci config. |
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I think I'll just wait for #35896 to land (tested locally that it helps). |
| if (std::optional<CKey> key = priv ? desc_spkm->GetKey(xpub.pubkey.GetID()) : std::nullopt) { | ||
| wallet_xprvs[xpub] = CExtKey(xpub, *key); | ||
| wallet_xpubs[xpub].emplace(desc_str, wallet->IsActiveScriptPubKeyMan(*desc_spkm), desc_spkm->HasPrivKey(xpub.pubkey.GetID())); | ||
| } |
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Can we look up the private key directly from each associated desc_spkm inside the existing loop in RPCMethod gethdkeys()?
diff --git a/src/wallet/rpc/wallet.cpp b/src/wallet/rpc/wallet.cpp
index cfba900d22..aa9dae8eb7 100644
--- a/src/wallet/rpc/wallet.cpp
+++ b/src/wallet/rpc/wallet.cpp
@@ -704,10 +704,8 @@ RPCMethod gethdkeys()
bool ok = desc_spkm->GetDescriptorString(desc_str, /*priv=*/false);
CHECK_NONFATAL(ok);
wallet_xpubs[xpub].emplace(desc_str, wallet->IsActiveScriptPubKeyMan(*desc_spkm), desc_spkm->HasPrivKey(xpub.pubkey.GetID()));
- }
- if (priv) {
- if (std::optional<CExtKey> xprv = wallet->GetExtKey(xpub)) {
- wallet_xprvs[xpub] = *xprv;
+ if (std::optional<CKey> key = priv ? desc_spkm->GetKey(xpub.pubkey.GetID()) : std::nullopt) {
+ wallet_xprvs[xpub] = CExtKey{xpub, *key};
}
}
}| }, | ||
| }, | ||
| RPCExamples{ | ||
| HelpExampleCli("derivehdkey", "m/87h/0h/0h") + HelpExampleRpc("derivehdkey", "") |
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The parameter is required.
diff --git a/src/wallet/rpc/wallet.cpp b/src/wallet/rpc/wallet.cpp
index cfba900d22..33450695e1 100644
--- a/src/wallet/rpc/wallet.cpp
+++ b/src/wallet/rpc/wallet.cpp
@@ -979,7 +979,7 @@ RPCMethod derivehdkey()
},
},
RPCExamples{
- HelpExampleCli("derivehdkey", "m/87h/0h/0h") + HelpExampleRpc("derivehdkey", "")
+ HelpExampleCli("derivehdkey", "m/87h/0h/0h") + HelpExampleRpc("derivehdkey", "\"m/87h/0h/0h\"")
+ HelpExampleCliNamed("derivehdkey", {{"path", "m/87h/0h/0h"}, {"private", "true"}})
+ HelpExampleRpcNamed("derivehdkey", {{"path", "m/87h/0h/0h"}, {"private", "true"}})
},6 participants
Adds a
derivehdkeyRPC that returns an xpub, or optionally the xprv, at an arbitrary BIP32 path (with at least one hardened step), derived from a wallet HD key.The main use case is coordinating a multisig setup, where each participant shares an xpub derived at a hardened path (e.g.
m/87h/0h/0h) distinct from their default single-signature descriptors. See the (updated)doc/multisig-tutorial.mdand (updated) functional test to see how that workflow improves.The first commits are some helpful helpers:
psbt_wallet_testsParseHDKeypathwould previously map overflowing values withouthto hardened.HasHardenedDerivation(), to enforce the "at least one hardened step" rulegethdkeyswhichderivehdkeyneedsGetKey()); behavior-preserving prep, also simplifiesgethdkeys.Meat and potatoes:
UnusedKeyfilter onGetHDPubKeysthat drives key selection.<0;1>syntax.