'Obtaining the size of an object';
A Condensation store does not provide any function to obtain the size of an object. The result of such a function would not be verifiable by the client anyway, which greatly limits its usefulness.
To reliably measure the size of an object, a client must download the object and verify its integrity.
Applications may store the size of relevant objects or subtrees (e.g. photo collection) as part of their private data. Since objects and subtrees are immutable, this is straightforward.