diff --git a/src/keystore.h b/src/keystore.h
--- a/src/keystore.h
+++ b/src/keystore.h
@@ -84,4 +84,9 @@
 typedef std::map<CKeyID, std::pair<CPubKey, std::vector<uint8_t>>>
     CryptedKeyMap;
 
+/**
+ * Return the CKeyID of the key involved in a script (if there is a unique one).
+ */
+CKeyID GetKeyForDestination(const CKeyStore &store, const CTxDestination &dest);
+
 #endif // BITCOIN_KEYSTORE_H
diff --git a/src/keystore.cpp b/src/keystore.cpp
--- a/src/keystore.cpp
+++ b/src/keystore.cpp
@@ -144,3 +144,12 @@
     LOCK(cs_KeyStore);
     return (!setWatchOnly.empty());
 }
+
+CKeyID GetKeyForDestination(const CKeyStore &store,
+                            const CTxDestination &dest) {
+    // Only supports destinations which map to single public keys, i.e. P2PKH.
+    if (auto id = boost::get<CKeyID>(&dest)) {
+        return *id;
+    }
+    return CKeyID();
+}