Time stamping software standards are published by ISO and IEC. They include the ISO/IEC 18014 series, which covers framework, producing independent tokens, linked tokens, and best practices.
ISO/IEC 18014 specifies time-stamping techniques. It consists of three parts, which include the general notion, models for a time-stamping service, data structures, and protocols. ISO/IEC 18014-1:2008 describes a framework and defines the basic notion, the data structures, and protocols which are used for any time-stamping technique. ISO/IEC 18014-1:2008: identifies the objective of a time-stamping authority; describes a general model on which time-stamping services are based; describes a process of generating and verifying time-stamp; defines the data structures of time-stamp token; defines the basic protocols of time-stamping; specifies the protocols between the involved entities.
This document specifies mechanisms that generate, renew, and verify independent time-stamps. In order to verify an independent time-stamp token, time-stamp verifiers do not need access to any other time-stamp tokens. That is, such time-stamp tokens are not linked.
ISO/IEC 18014-3:2009 describes a general model for time-stamping services producing linked tokens, describes the basic components used to construct a time-stamping service producing linked tokens, defines the data structures used to interact with a time-stamping service producing linked tokens, describes specific instances of time-stamping services producing linked tokens, and defines a protocol to be utilized by time-stamping services producing linked tokens for the purpose of extending linked tokens to published values.
ISO/IEC TR 29149:2012 explains how to provide and use time-stamping services so that time-stamp tokens are effective when used to provide timeliness, data integrity, and non-repudiation services in conjunction with other mechanisms. It defines: how time-stamp requesters should use time-stamp token generation services; how TSAs (time-stamping authorities) should provide a service of guaranteed quality; how TSAs should deserve trust based on good practices; which algorithms and parameters should be used in TST (time-stamp token) generation and TST renewal, so that TSTs resist during the time period during which the TSTs can be verified as being valid; how time-stamp verifiers should use the time-stamp token verification services, both when validating individual TSTs, and when validating sequences of renewal TSTs.