Rigid body Door requiring a key?

here is my script which basically allows objects to be dragged around using the rigid body function, I have a system with the doors in my game which have a rigid body on them and a configurable joint which allows the doors to be clicked on and pushed open just like in Amnesia The Dark Descent a fairly popular FPS Horror. I need a system where some doors require keys. How would I go about this? If anyone has any idea on how to have a locked rigid body door so you need a key to unlock it, please I am open to any help!

var spring = 50.0; var damper = 5.0; var drag = 10.0; var angularDrag = 5.0; var distance = 0.2; var pushForce = 0.2; var attachToCenterOfMass = false;

var highlightMaterial : Material; private var highlightObject : GameObject;

private var springJoint : SpringJoint;

function Update() { var mainCamera = FindCamera();

 highlightObject = null;
 if( springJoint != null && springJoint.connectedBody != null )
 {
     highlightObject = springJoint.connectedBody.gameObject;
 }
 else
 {
     // We need to actually hit an object
     var hitt : RaycastHit;
     if( Physics.Raycast(mainCamera.ScreenPointToRay(Input.mousePosition),  hitt, 100 ) ) {
         if( hitt.rigidbody && !hitt.rigidbody.isKinematic ) {
             highlightObject = hitt.rigidbody.gameObject;
         }
     }
 }
 
     
 // Make sure the user pressed the mouse down
 if (!Input.GetMouseButtonDown (0))
     return;

     
 // We need to actually hit an object
 var hit : RaycastHit;
 if (!Physics.Raycast(mainCamera.ScreenPointToRay(Input.mousePosition),  hit, 100)) {
     return;
 }
 // We need to hit a rigidbody that is not kinematic
 if (!hit.rigidbody || hit.rigidbody.isKinematic) {
     return;
 }
 
 if (!springJoint)
 {
     var go = new GameObject("Rigidbody dragger");
     body = go.AddComponent ("Rigidbody");
     springJoint = go.AddComponent ("SpringJoint");
     body.isKinematic = true;
 }
 
 springJoint.transform.position = hit.point;
 if (attachToCenterOfMass)
 {
     var anchor = transform.TransformDirection(hit.rigidbody.centerOfMass) + hit.rigidbody.transform.position;
     anchor = springJoint.transform.InverseTransformPoint(anchor);
     springJoint.anchor = anchor;
 }
 else
 {
     springJoint.anchor = Vector3.zero;
 }
 
 springJoint.spring = spring;
 springJoint.damper = damper;
 springJoint.maxDistance = distance;
 springJoint.connectedBody = hit.rigidbody;
 
 DragObject(hit.distance, hit.point, mainCamera.ScreenPointToRay(Input.mousePosition).direction);

}

function DragObject (distance : float, hitpoint : Vector3, dir : Vector3) { var startTime = Time.time; var mousePos = Input.mousePosition;

 var oldDrag = springJoint.connectedBody.drag;
 var oldAngularDrag = springJoint.connectedBody.angularDrag;
 springJoint.connectedBody.drag = drag;
 springJoint.connectedBody.angularDrag = angularDrag;
 var mainCamera = FindCamera();
 while (Input.GetMouseButton (0))
 {
     var ray = mainCamera.ScreenPointToRay (Input.mousePosition);
     springJoint.transform.position = ray.GetPoint(distance);
     yield;
 }
 
 if (Mathf.Abs(mousePos.x - Input.mousePosition.x) <= 2 && Mathf.Abs(mousePos.y - Input.mousePosition.y) <= 2 && Time.time - startTime < .2 && springJoint.connectedBody)
 {
     dir.y = 0;
     dir.Normalize();
     springJoint.connectedBody.AddForceAtPosition(dir * pushForce, hitpoint, ForceMode.VelocityChange);
     ToggleLight( springJoint.connectedBody.gameObject );
 }    
 
 
 if (springJoint.connectedBody)
 {
     springJoint.connectedBody.drag = oldDrag;
     springJoint.connectedBody.angularDrag = oldAngularDrag;
     springJoint.connectedBody = null;
 }

}

static function ToggleLight( go : GameObject ) {
var theLight : Light = go.GetComponentInChildren(Light); if( !theLight ) return;

 theLight.enabled = !theLight.enabled;
 var illumOn = theLight.enabled;
 var renderers = go.GetComponentsInChildren(MeshRenderer);
 for( var r : MeshRenderer in renderers )
 {
     if( r.gameObject.layer == 1 )
     {
         r.material.shader = Shader.Find(illumOn ? "Self-Illumin/Diffuse" : "Diffuse");
     }
 }

}

function FindCamera () { if (camera) return camera; else return Camera.main; }

function OnPostRender() { if( highlightObject == null ) return;

 var go = highlightObject;
 highlightMaterial.SetPass( 0 );
 var meshes = go.GetComponentsInChildren(MeshFilter);
 for( var m : MeshFilter in meshes )
 {
     Graphics.DrawMeshNow( m.sharedMesh, m.transform.position, m.transform.rotation );
 }

}