object: Add public key header type

Object can contain public key header. It will be used
for object verification. This header can contain owner's
public key or be the part of x509 chain verification in
couple with verification header.

object/types.go

@@ -67,6 +67,8 @@ const (
 	IntegrityHdr
 	// StorageGroupHdr is a storage group header type.
 	StorageGroupHdr
+	// PublicKeyHdr is a public key header type.
+	PublicKeyHdr
 )
 
 var (
@@ -140,6 +142,8 @@ func (m Header) typeOf(t isHeader_Value) (ok bool) {
 		_, ok = m.Value.(*Header_Integrity)
 	case *Header_StorageGroup:
 		_, ok = m.Value.(*Header_StorageGroup)
+	case *Header_PublicKey:
+		_, ok = m.Value.(*Header_PublicKey)
 	}
 	return
 }
@@ -168,6 +172,8 @@ func HeaderType(t headerType) Pred {
 		return func(h *Header) bool { _, ok := h.Value.(*Header_Integrity); return ok }
 	case StorageGroupHdr:
 		return func(h *Header) bool { _, ok := h.Value.(*Header_StorageGroup); return ok }
+	case PublicKeyHdr:
+		return func(h *Header) bool { _, ok := h.Value.(*Header_PublicKey); return ok }
 	default:
 		return nil
 	}

object/types.proto

@@ -45,6 +45,8 @@ message Header {
         IntegrityHeader Integrity              = 9;
         // StorageGroup contains meta information for the data audit
         storagegroup.StorageGroup StorageGroup = 10;
+        // PublicKey of owner of the object. Key is used for verification and can be based on NeoID or x509 cert.
+        PublicKey PublicKey                    = 11;
     }
 }
 
@@ -122,3 +124,8 @@ message Object {
     // Payload is an object's payload
     bytes Payload             = 3;
 }
+
+message PublicKey {
+    // Value contains marshaled ecdsa public key
+    bytes Value = 1;
+}