Add GetEncryptionKey() and HasEncryptionKeys() to WalletStorage

Adds functions in WalletStorage that allow ScriptPubKeyMans to check
and get encryption keys from the wallet.

src/wallet/scriptpubkeyman.h

@@ -31,6 +31,8 @@ public:
     virtual void UnsetBlankWalletFlag(WalletBatch&) = 0;
     virtual bool CanSupportFeature(enum WalletFeature) const = 0;
     virtual void SetMinVersion(enum WalletFeature, WalletBatch* = nullptr, bool = false) = 0;
+    virtual const CKeyingMaterial& GetEncryptionKey() const = 0;
+    virtual bool HasEncryptionKeys() const = 0;
     virtual bool IsLocked() const = 0;
 };
 

src/wallet/wallet.cpp

@@ -4056,3 +4056,13 @@ LegacyScriptPubKeyMan* CWallet::GetLegacyScriptPubKeyMan() const
 {
     return m_spk_man.get();
 }
+
+const CKeyingMaterial& CWallet::GetEncryptionKey() const
+{
+    return vMasterKey;
+}
+
+bool CWallet::HasEncryptionKeys() const
+{
+    return !mapMasterKeys.empty();
+}

src/wallet/wallet.h

@@ -1136,6 +1136,9 @@ public:
 
     LegacyScriptPubKeyMan* GetLegacyScriptPubKeyMan() const;
 
+    const CKeyingMaterial& GetEncryptionKey() const override;
+    bool HasEncryptionKeys() const override;
+
     // Temporary LegacyScriptPubKeyMan accessors and aliases.
     friend class LegacyScriptPubKeyMan;
     std::unique_ptr<LegacyScriptPubKeyMan> m_spk_man = MakeUnique<LegacyScriptPubKeyMan>(*this);