This Recommendation | International Standard will define those TTP services needed to support the application of digital
signatures for the purpose of non-repudiation of creation of documents.
This Recommendation | International Standard will also define interfaces and protocols to enable interoperability
between entities associated with these TTP services.
Definitions of technical services and protocols are required to allow for the implementation of TTP services and related
This Recommendation | International Standard focuses on:
? implementation and interoperability;
? service specifications; and
? technical requirements.
This Recommendation | International Standard does not describe the management of TTPs or other organizational,
operational or personal issues. Those topics are mainly covered in ITU-T Rec. X.842 | ISO/IEC TR 14516, Information
technology ? Security techniques ? Guidelines on the use and management of Trusted Third Party services.
NOTE 1 ? Because interoperability is the main issue of this Recommendation | International Standard, the following restrictions
i) Only those services which may be offered by a TTP, either to end entities or to another TTP, are covered in this
Recommendation | International Standard.
ii) Only those services which may be requested and/or delivered by means of standardizable digital messages are
iii) Only those services for which widely acceptable standardized messages can be agreed upon at the time this
Recommendation | International Standard is published are specified in detail.
Further services will be specified in separate documents when widely acceptable standardized messages are available for them. In
particular, time stamping services will be defined in a separate document.
NOTE 2 ? The data structures and messages in this Recommendation | International Standard will be specified in accordance to
RFC documents, RFC 2510 and RFC 2511 (for certificate management services) and to RFC 2560 (for OCSP services). The
certificate request format also allows interoperability with PKCS#10. See Annex C for references to the documents mentioned in
NOTE 3 ? Other standardization efforts for TTP services in specific environments and applications, like SET or EDIFACT, exist.
These are outside of the scope of this Recommendation | International Standard.
NOTE 4 ? This Recommendation | International Standard defines technical specifications for services. These specifications are
independent of policies, specific legal regulations, and organizational models (which, for example, might define how duties and
responsibilities are shared between Certification Authorities and Registration Authorities). Of course, the policy of TTPs offering
the services described in this Recommendation | International Standard will need to specify how legal regulations and the other
aspects mentioned before will be fulfilled by the TTP. In particular, the policy has to specify how the validity of digital signatures
and certificates is determined.