Section 9(7) in The Digital Signature (End entity) Rules, 2015
(7)To create long term valid xml digital signature-(a)a time stamp shall be applied initially to the signed document, where the Initial time stamp shall cover all the electronic record and signature(s);(b)a nested time stamp option shall be used to ensure signature validity past the time-stamping service provider (tssp)'s key or algorithm expiry where as nesting of time stamps implies that a subsequent time stamp shall be applied to the prior time stamp;(c)signature(s) and time stamps may be embedded in the data itself or stored separately as standalone.
