Merge #13723: PSBT key path cleanups

917353c8b0eff4cd95f9a5f7719f6756bb8338b1 Make SignPSBTInput operate on a private SignatureData object (Pieter Wuille)
cad5dd2368109ec398a3b79c8b9e94dfd23f0845 Pass HD path data through SignatureData (Pieter Wuille)
03a99586a398ee38f40c3b72d24c6a2ba4b88579 Implement key origin lookup in CWallet (Pieter Wuille)
3b01efa0d1bf3d23d1b7b7e518849f1fc26314f9 [MOVEONLY] Move ParseHDKeypath to utilstrencodings (Pieter Wuille)
81e1dd5ce1a32114a38691ec6b55e72ab04dbbb1 Generalize PublicOnlySigningProvider into HidingSigningProvider (Pieter Wuille)
84f1f1bfdf900cd28099e428441aa42f9d11a0ed Make SigningProvider expose key origin information (Pieter Wuille)
611ab307fbd8b6f8f7ffc1d569bb86d1f9cb4e92 Introduce KeyOriginInfo for fingerprint + path (Pieter Wuille)

Pull request description:

  This PR adds "key origin" (master fingeprint + key path) information to what is exposed from `SigningProvider`s, allowing this information to be used by the generic PSBT code instead of having the RPC pull it directly from the wallet.

  This is also a preparation to having PSBT interact with output descriptors, which can then directly expose key origin information for the scripts they generate.

Tree-SHA512: c718382ba8ba2d6fc9a32c062bd4cff08b6f39b133838aa03115c39aeca0f654c7cc3ec72d87005bf8306e550824cd8eb9d60f0bd41784a3e22e17b2afcfe833

2 files changed, 77 insertions, 27 deletions

diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index 23af1bd97f..d779910425 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -50,10 +50,6 @@ static bool GetCScript(const SigningProvider& provider, const SignatureData& sig
 
 static bool GetPubKey(const SigningProvider& provider, SignatureData& sigdata, const CKeyID& address, CPubKey& pubkey)
 {
-    if (provider.GetPubKey(address, pubkey)) {
-        sigdata.misc_pubkeys.emplace(pubkey.GetID(), pubkey);
-        return true;
-    }
     // Look for pubkey in all partial sigs
     const auto it = sigdata.signatures.find(address);
     if (it != sigdata.signatures.end()) {
@@ -63,7 +59,15 @@ static bool GetPubKey(const SigningProvider& provider, SignatureData& sigdata, c
     // Look for pubkey in pubkey list
     const auto& pk_it = sigdata.misc_pubkeys.find(address);
     if (pk_it != sigdata.misc_pubkeys.end()) {
-        pubkey = pk_it->second;
+        pubkey = pk_it->second.first;
+        return true;
+    }
+    // Query the underlying provider
+    if (provider.GetPubKey(address, pubkey)) {
+        KeyOriginInfo info;
+        if (provider.GetKeyOrigin(address, info)) {
+            sigdata.misc_pubkeys.emplace(address, std::make_pair(pubkey, std::move(info)));
+        }
         return true;
     }
     return false;
@@ -232,7 +236,7 @@ bool ProduceSignature(const SigningProvider& provider, const BaseSignatureCreato
     return sigdata.complete;
 }
 
-bool SignPSBTInput(const SigningProvider& provider, const CMutableTransaction& tx, PSBTInput& input, SignatureData& sigdata, int index, int sighash)
+bool SignPSBTInput(const SigningProvider& provider, const CMutableTransaction& tx, PSBTInput& input, int index, int sighash)
 {
     // if this input has a final scriptsig or scriptwitness, don't do anything with it
     if (!input.final_script_sig.empty() || !input.final_script_witness.IsNull()) {
@@ -240,6 +244,7 @@ bool SignPSBTInput(const SigningProvider& provider, const CMutableTransaction& t
     }
 
     // Fill SignatureData with input info
+    SignatureData sigdata;
     input.FillSignatureData(sigdata);
 
     // Get UTXO
@@ -271,6 +276,16 @@ bool SignPSBTInput(const SigningProvider& provider, const CMutableTransaction& t
     // Verify that a witness signature was produced in case one was required.
     if (require_witness_sig && !sigdata.witness) return false;
     input.FromSignatureData(sigdata);
+
+    // If both UTXO types are present, drop the unnecessary one.
+    if (input.non_witness_utxo && !input.witness_utxo.IsNull()) {
+        if (sigdata.witness) {
+            input.non_witness_utxo = nullptr;
+        } else {
+            input.witness_utxo.SetNull();
+        }
+    }
+
     return sig_complete;
 }
 
@@ -541,7 +556,7 @@ void PSBTInput::FillSignatureData(SignatureData& sigdata) const
         sigdata.witness_script = witness_script;
     }
     for (const auto& key_pair : hd_keypaths) {
-        sigdata.misc_pubkeys.emplace(key_pair.first.GetID(), key_pair.first);
+        sigdata.misc_pubkeys.emplace(key_pair.first.GetID(), key_pair);
     }
 }
 
@@ -569,6 +584,9 @@ void PSBTInput::FromSignatureData(const SignatureData& sigdata)
     if (witness_script.empty() && !sigdata.witness_script.empty()) {
         witness_script = sigdata.witness_script;
     }
+    for (const auto& entry : sigdata.misc_pubkeys) {
+        hd_keypaths.emplace(entry.second);
+    }
 }
 
 void PSBTInput::Merge(const PSBTInput& input)
@@ -610,7 +628,7 @@ void PSBTOutput::FillSignatureData(SignatureData& sigdata) const
         sigdata.witness_script = witness_script;
     }
     for (const auto& key_pair : hd_keypaths) {
-        sigdata.misc_pubkeys.emplace(key_pair.first.GetID(), key_pair.first);
+        sigdata.misc_pubkeys.emplace(key_pair.first.GetID(), key_pair);
     }
 }
 
@@ -622,6 +640,9 @@ void PSBTOutput::FromSignatureData(const SignatureData& sigdata)
     if (witness_script.empty() && !sigdata.witness_script.empty()) {
         witness_script = sigdata.witness_script;
     }
+    for (const auto& entry : sigdata.misc_pubkeys) {
+        hd_keypaths.emplace(entry.second);
+    }
 }
 
 bool PSBTOutput::IsNull() const
@@ -638,14 +659,26 @@ void PSBTOutput::Merge(const PSBTOutput& output)
     if (witness_script.empty() && !output.witness_script.empty()) witness_script = output.witness_script;
 }
 
-bool PublicOnlySigningProvider::GetCScript(const CScriptID &scriptid, CScript& script) const
+bool HidingSigningProvider::GetCScript(const CScriptID& scriptid, CScript& script) const
 {
     return m_provider->GetCScript(scriptid, script);
 }
 
-bool PublicOnlySigningProvider::GetPubKey(const CKeyID &address, CPubKey& pubkey) const
+bool HidingSigningProvider::GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const
+{
+    return m_provider->GetPubKey(keyid, pubkey);
+}
+
+bool HidingSigningProvider::GetKey(const CKeyID& keyid, CKey& key) const
+{
+    if (m_hide_secret) return false;
+    return m_provider->GetKey(keyid, key);
+}
+
+bool HidingSigningProvider::GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const
 {
-    return m_provider->GetPubKey(address, pubkey);
+    if (m_hide_origin) return false;
+    return m_provider->GetKeyOrigin(keyid, info);
 }
 
 bool FlatSigningProvider::GetCScript(const CScriptID& scriptid, CScript& script) const { return LookupHelper(scripts, scriptid, script); }
diff --git a/src/script/sign.h b/src/script/sign.h
index 7ade715ee2..18b7320998 100644
--- a/src/script/sign.h
+++ b/src/script/sign.h
@@ -20,6 +20,12 @@ class CTransaction;
 
 struct CMutableTransaction;
 
+struct KeyOriginInfo
+{
+    unsigned char fingerprint[4];
+    std::vector<uint32_t> path;
+};
+
 /** An interface to be implemented by keystores that support signing. */
 class SigningProvider
 {
@@ -28,19 +34,24 @@ public:
     virtual bool GetCScript(const CScriptID &scriptid, CScript& script) const { return false; }
     virtual bool GetPubKey(const CKeyID &address, CPubKey& pubkey) const { return false; }
     virtual bool GetKey(const CKeyID &address, CKey& key) const { return false; }
+    virtual bool GetKeyOrigin(const CKeyID& id, KeyOriginInfo& info) const { return false; }
 };
 
 extern const SigningProvider& DUMMY_SIGNING_PROVIDER;
 
-class PublicOnlySigningProvider : public SigningProvider
+class HidingSigningProvider : public SigningProvider
 {
 private:
+    const bool m_hide_secret;
+    const bool m_hide_origin;
     const SigningProvider* m_provider;
 
 public:
-    PublicOnlySigningProvider(const SigningProvider* provider) : m_provider(provider) {}
-    bool GetCScript(const CScriptID &scriptid, CScript& script) const;
-    bool GetPubKey(const CKeyID &address, CPubKey& pubkey) const;
+    HidingSigningProvider(const SigningProvider* provider, bool hide_secret, bool hide_origin) : m_hide_secret(hide_secret), m_hide_origin(hide_origin), m_provider(provider) {}
+    bool GetCScript(const CScriptID& scriptid, CScript& script) const override;
+    bool GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const override;
+    bool GetKey(const CKeyID& keyid, CKey& key) const override;
+    bool GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const override;
 };
 
 struct FlatSigningProvider final : public SigningProvider
@@ -98,7 +109,7 @@ struct SignatureData {
     CScript witness_script; ///< The witnessScript (if any) for the input. witnessScripts are used in P2WSH outputs.
     CScriptWitness scriptWitness; ///< The scriptWitness of an input. Contains complete signatures or the traditional partial signatures format. scriptWitness is part of a transaction input per BIP 144.
     std::map<CKeyID, SigPair> signatures; ///< BIP 174 style partial signatures for the input. May contain all signatures necessary for producing a final scriptSig or scriptWitness.
-    std::map<CKeyID, CPubKey> misc_pubkeys;
+    std::map<CKeyID, std::pair<CPubKey, KeyOriginInfo>> misc_pubkeys;
 
     SignatureData() {}
     explicit SignatureData(const CScript& script) : scriptSig(script) {}
@@ -155,7 +166,7 @@ void UnserializeFromVector(Stream& s, X&... args)
 
 // Deserialize HD keypaths into a map
 template<typename Stream>
-void DeserializeHDKeypaths(Stream& s, const std::vector<unsigned char>& key, std::map<CPubKey, std::vector<uint32_t>>& hd_keypaths)
+void DeserializeHDKeypaths(Stream& s, const std::vector<unsigned char>& key, std::map<CPubKey, KeyOriginInfo>& hd_keypaths)
 {
     // Make sure that the key is the size of pubkey + 1
     if (key.size() != CPubKey::PUBLIC_KEY_SIZE + 1 && key.size() != CPubKey::COMPRESSED_PUBLIC_KEY_SIZE + 1) {
@@ -172,25 +183,31 @@ void DeserializeHDKeypaths(Stream& s, const std::vector<unsigned char>& key, std
 
     // Read in key path
     uint64_t value_len = ReadCompactSize(s);
-    std::vector<uint32_t> keypath;
-    for (unsigned int i = 0; i < value_len; i += sizeof(uint32_t)) {
+    if (value_len % 4 || value_len == 0) {
+        throw std::ios_base::failure("Invalid length for HD key path");
+    }
+
+    KeyOriginInfo keypath;
+    s >> keypath.fingerprint;
+    for (unsigned int i = 4; i < value_len; i += sizeof(uint32_t)) {
         uint32_t index;
         s >> index;
-        keypath.push_back(index);
+        keypath.path.push_back(index);
     }
 
     // Add to map
-    hd_keypaths.emplace(pubkey, keypath);
+    hd_keypaths.emplace(pubkey, std::move(keypath));
 }
 
 // Serialize HD keypaths to a stream from a map
 template<typename Stream>
-void SerializeHDKeypaths(Stream& s, const std::map<CPubKey, std::vector<uint32_t>>& hd_keypaths, uint8_t type)
+void SerializeHDKeypaths(Stream& s, const std::map<CPubKey, KeyOriginInfo>& hd_keypaths, uint8_t type)
 {
     for (auto keypath_pair : hd_keypaths) {
         SerializeToVector(s, type, MakeSpan(keypath_pair.first));
-        WriteCompactSize(s, keypath_pair.second.size() * sizeof(uint32_t));
-        for (auto& path : keypath_pair.second) {
+        WriteCompactSize(s, (keypath_pair.second.path.size() + 1) * sizeof(uint32_t));
+        s << keypath_pair.second.fingerprint;
+        for (const auto& path : keypath_pair.second.path) {
             s << path;
         }
     }
@@ -205,7 +222,7 @@ struct PSBTInput
     CScript witness_script;
     CScript final_script_sig;
     CScriptWitness final_script_witness;
-    std::map<CPubKey, std::vector<uint32_t>> hd_keypaths;
+    std::map<CPubKey, KeyOriginInfo> hd_keypaths;
     std::map<CKeyID, SigPair> partial_sigs;
     std::map<std::vector<unsigned char>, std::vector<unsigned char>> unknown;
     int sighash_type = 0;
@@ -418,7 +435,7 @@ struct PSBTOutput
 {
     CScript redeem_script;
     CScript witness_script;
-    std::map<CPubKey, std::vector<uint32_t>> hd_keypaths;
+    std::map<CPubKey, KeyOriginInfo> hd_keypaths;
     std::map<std::vector<unsigned char>, std::vector<unsigned char>> unknown;
 
     bool IsNull() const;
@@ -687,7 +704,7 @@ bool SignSignature(const SigningProvider &provider, const CScript& fromPubKey, C
 bool SignSignature(const SigningProvider &provider, const CTransaction& txFrom, CMutableTransaction& txTo, unsigned int nIn, int nHashType);
 
 /** Signs a PSBTInput, verifying that all provided data matches what is being signed. */
-bool SignPSBTInput(const SigningProvider& provider, const CMutableTransaction& tx, PSBTInput& input, SignatureData& sigdata, int index, int sighash = 1);
+bool SignPSBTInput(const SigningProvider& provider, const CMutableTransaction& tx, PSBTInput& input, int index, int sighash = SIGHASH_ALL);
 
 /** Extract signature data from a transaction input, and insert it. */
 SignatureData DataFromTransaction(const CMutableTransaction& tx, unsigned int nIn, const CTxOut& txout);