bunch of fixes

Bitvault/VaultKey.cs

@@ -1,3 +1,14 @@
 namespace Bitvault;
 
-public record VaultKey(byte[] Salt, byte[] Public, byte[] Private);
+public record VaultKey(byte[] Phrase, byte[] Public, byte[] Private) :
+    IDisposable
+{
+    public void Dispose()
+    {
+        GC.SuppressFinalize(this);
+
+        Array.Clear(Phrase, 0, Phrase.Length);
+        Array.Clear(Public, 0, Public.Length);
+        Array.Clear(Private, 0, Private.Length);
+    }
+}