7 files changed, 105 insertions, 0 deletions
diff --git a/src/wallet/external_signer.cpp b/src/wallet/external_signer.cpp
index ec915d5c5e..baf97700e7 100644
--- a/src/wallet/external_signer.cpp
+++ b/src/wallet/external_signer.cpp
@@ -55,6 +55,11 @@ bool ExternalSigner::Enumerate(const std::string& command, std::vector<ExternalS
     return true;
 }
 
+UniValue ExternalSigner::DisplayAddress(const std::string& descriptor) const
+{
+    return RunCommandParseJSON(m_command + " --fingerprint \"" + m_fingerprint + "\"" + NetworkArg() + " displayaddress --desc \"" + descriptor + "\"");
+}
+
 UniValue ExternalSigner::GetDescriptors(int account)
 {
     return RunCommandParseJSON(m_command + " --fingerprint \"" + m_fingerprint + "\"" + NetworkArg() + " getdescriptors --account " + strprintf("%d", account));
diff --git a/src/wallet/external_signer.h b/src/wallet/external_signer.h
index 944dd7d5ef..198a939d3d 100644
--- a/src/wallet/external_signer.h
+++ b/src/wallet/external_signer.h
@@ -49,6 +49,11 @@ public:
     //! @param[out] success     Boolean
     static bool Enumerate(const std::string& command, std::vector<ExternalSigner>& signers, std::string chain, bool ignore_errors = false);
 
+    //! Display address on the device. Calls `<command> displayaddress --desc <descriptor>`.
+    //! @param[in] descriptor Descriptor specifying which address to display.
+    //!            Must include a public key or xpub, as well as key origin.
+    UniValue DisplayAddress(const std::string& descriptor) const;
+
     //! Get receive and change Descriptor(s) from device for a given account.
     //! Calls `<command> getdescriptors --account <account>`
     //! @param[in] account  which BIP32 account to use (e.g. `m/44'/0'/account'`)
diff --git a/src/wallet/external_signer_scriptpubkeyman.cpp b/src/wallet/external_signer_scriptpubkeyman.cpp
index b8bd69f941..a2071e521a 100644
--- a/src/wallet/external_signer_scriptpubkeyman.cpp
+++ b/src/wallet/external_signer_scriptpubkeyman.cpp
@@ -43,4 +43,39 @@ ExternalSigner ExternalSignerScriptPubKeyMan::GetExternalSigner() {
     return signers[0];
 }
 
+bool ExternalSignerScriptPubKeyMan::DisplayAddress(const CScript scriptPubKey, const ExternalSigner &signer) const
+{
+    // TODO: avoid the need to infer a descriptor from inside a descriptor wallet
+    auto provider = GetSolvingProvider(scriptPubKey);
+    auto descriptor = InferDescriptor(scriptPubKey, *provider);
+
+    signer.DisplayAddress(descriptor->ToString());
+    // TODO inspect result
+    return true;
+}
+
+// If sign is true, transaction must previously have been filled
+TransactionError ExternalSignerScriptPubKeyMan::FillPSBT(PartiallySignedTransaction& psbt, int sighash_type, bool sign, bool bip32derivs, int* n_signed) const
+{
+    if (!sign) {
+        return DescriptorScriptPubKeyMan::FillPSBT(psbt, sighash_type, false, bip32derivs, n_signed);
+    }
+
+    // Already complete if every input is now signed
+    bool complete = true;
+    for (const auto& input : psbt.inputs) {
+        // TODO: for multisig wallets, we should only care if all _our_ inputs are signed
+        complete &= PSBTInputSigned(input);
+    }
+    if (complete) return TransactionError::OK;
+
+    std::string strFailReason;
+    if(!GetExternalSigner().SignTransaction(psbt, strFailReason)) {
+        tfm::format(std::cerr, "Failed to sign: %s\n", strFailReason);
+        return TransactionError::EXTERNAL_SIGNER_FAILED;
+    }
+    FinalizePSBT(psbt); // This won't work in a multisig setup
+    return TransactionError::OK;
+}
+
 #endif
diff --git a/src/wallet/external_signer_scriptpubkeyman.h b/src/wallet/external_signer_scriptpubkeyman.h
index cef0a18075..1cde143ef9 100644
--- a/src/wallet/external_signer_scriptpubkeyman.h
+++ b/src/wallet/external_signer_scriptpubkeyman.h
@@ -25,6 +25,7 @@ class ExternalSignerScriptPubKeyMan : public DescriptorScriptPubKeyMan
 
   static ExternalSigner GetExternalSigner();
 
+  bool DisplayAddress(const CScript scriptPubKey, const ExternalSigner &signer) const;
 };
 #endif
 
diff --git a/src/wallet/rpcsigner.cpp b/src/wallet/rpcsigner.cpp
index 76f4f3c6aa..607b778c68 100644
--- a/src/wallet/rpcsigner.cpp
+++ b/src/wallet/rpcsigner.cpp
@@ -3,6 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <chainparamsbase.h>
+#include <key_io.h>
 #include <rpc/server.h>
 #include <rpc/util.h>
 #include <util/strencodings.h>
@@ -57,6 +58,41 @@ static RPCHelpMan enumeratesigners()
     };
 }
 
+static RPCHelpMan signerdisplayaddress()
+{
+    return RPCHelpMan{
+        "signerdisplayaddress",
+        "Display address on an external signer for verification.\n",
+        {
+            {"address",     RPCArg::Type::STR, RPCArg::Optional::NO, /* default_val */ "", "bitcoin address to display"},
+        },
+        RPCResult{RPCResult::Type::NONE,"",""},
+        RPCExamples{""},
+        [](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue {
+            std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
+            if (!wallet) return NullUniValue;
+            CWallet* const pwallet = wallet.get();
+
+            LOCK(pwallet->cs_wallet);
+
+            CTxDestination dest = DecodeDestination(request.params[0].get_str());
+
+            // Make sure the destination is valid
+            if (!IsValidDestination(dest)) {
+                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid address");
+            }
+
+            if (!pwallet->DisplayAddress(dest)) {
+                throw JSONRPCError(RPC_WALLET_ERROR, "Failed to display address");
+            }
+
+            UniValue result(UniValue::VOBJ);
+            result.pushKV("address", request.params[0].get_str());
+            return result;
+        }
+    };
+}
+
 Span<const CRPCCommand> GetSignerRPCCommands()
 {
 
@@ -65,6 +101,7 @@ static const CRPCCommand commands[] =
 { // category              actor (function)
   // --------------------- ------------------------
   { "signer",              &enumeratesigners,      },
+  { "signer",              &signerdisplayaddress,  },
 };
 // clang-format on
     return MakeSpan(commands);
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 795299d103..7c15438067 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -3587,6 +3587,25 @@ ExternalSigner CWallet::GetExternalSigner()
 }
 #endif
 
+bool CWallet::DisplayAddress(const CTxDestination& dest)
+{
+#ifdef ENABLE_EXTERNAL_SIGNER
+    CScript scriptPubKey = GetScriptForDestination(dest);
+    const auto spk_man = GetScriptPubKeyMan(scriptPubKey);
+    if (spk_man == nullptr) {
+        return false;
+    }
+    auto signer_spk_man = dynamic_cast<ExternalSignerScriptPubKeyMan*>(spk_man);
+    if (signer_spk_man == nullptr) {
+        return false;
+    }
+    ExternalSigner signer = GetExternalSigner(); // TODO: move signer in spk_man
+    return signer_spk_man->DisplayAddress(scriptPubKey, signer);
+#else
+    return false;
+#endif
+}
+
 void CWallet::LockCoin(const COutPoint& output)
 {
     AssertLockHeld(cs_wallet);
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 3c27aee488..eb797938cd 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -842,6 +842,9 @@ public:
 #ifdef ENABLE_EXTERNAL_SIGNER
     ExternalSigner GetExternalSigner() EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 #endif
+    /** Display address on an external signer. Returns false if external signer support is not compiled */
+    bool DisplayAddress(const CTxDestination& dest) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
+
     bool IsLockedCoin(uint256 hash, unsigned int n) const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void LockCoin(const COutPoint& output) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void UnlockCoin(const COutPoint& output) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);