how to check all asset bundles hash before download?

Is it have any script can check the assetbundles hash before start downloading with www.loadfromcacheordowload ??
i try to show the client to know how many assetbundles that need to update.

example:
i got assetbundles manifest

ManifestFileVersion: 0
AssetBundleManifest:
AssetBundleInfos:
Info_0:
Name: scene/a
Dependencies: {}
Info_1:
Name: scene/b
Dependencies: {}
Info_2:
Name: scene/c
Dependencies:
Dependency_0: object/1
Dependency_1: object/2
Dependency_2: object/3
Dependency_3: object/4

and im just update the object/3 and object/4
i want to show client that im have 2 objects need download
not showing total 7 objects in the list.

 

Use version parameter: http://docs.unity3d.com/ScriptReference/WWW.LoadFromCacheOrDownload.html

 

im just want to check but not download or load yet,
is it possible for that?

 

From docs:

 

Thanks