The ASN.1 Project was established in February 2001 by ITU-T Study Group 7 to assist existing users of ASN.1 (Rec. ITU-T  X.680, X.690 and X.890 series) within and outside of ITU-T, and to promote the use of ASN.1 across a wide range of industries and standards bodies. Since 17 September 2001, the responsibility for the ASN.1 Project resides with Study Group 17 and the Project now also encompasses Object Identifiers (OIDs) and Registration Authorities (as defined in the Rec. ITU-T  X.660 and X.670 series).

The Project provides speakers and tutorial material, and coordinates the provision of tool support to users.

It maintains an up-to-date database of error-free ASN.1 modules within all ITU-T Recommendations (extending to other bodies over time).

The Project involves close liaison with all ITU-T Study Groups and coordination of notations used for protocol specification in those groups. It also extends its interests into several ISO/IEC JTC 1 Subcommittees, the ITU-R, the UPU, the IETF and other groups, and to a number of industry consortia.

The Project also helps people and organizations to set up a Registration Authority for OIDs.

Olivier Dubuisson (France Télécom, France) has been appointed as Project Leader. The Project Leader in consultation with the SG 17 Chairman and TSB manages decisions related to the operation of the ITU-T Project including the use of its name and resources. All such decisions are reported to each Plenary session of SG 17.

The Project Leader establishes a close working relationship with the SG 17 management team and with the Promotion, Edition and Production Department and other parts of the TSB.

ASN.1 is a well-established technology that is widely used both within ITU-T and outside of it. The notation is supported by a number of software vendors.

The Encoding Control Notation, ECN (Rec. ITU-T  X.692), makes it possible for ASN.1 to be used for all existing telecom/computer protocols. This extends the use of ASN.1 into new areas, and increases the need for coordination of the activity.

The XML Encoding Rules, XER (Rec. ITU-T X.693), allows the encoding of ASN.1 values in XML markup format for the purpose of transmission. A canonical XML encoding is also specified in this document. ASN.1 can now be used as a schema for XML, in the same way as XSD and RELAX NG are used.

The mapping from W3C XML Schemas into ASN.1 modules (Rec. ITU-T X.694) takes as input a schema written in XML Schema and produces an ASN.1 module containing a set of type definitions (and, optionally, an XER encoding instruction section to keep the same XML encoding, if needed), in such a way that there is a one-to-one correspondence between ASN.1 abstract values and valid XML instances. This technique can be applied to any given XML application language. ASN.1 standardized encoding rules such as DER (a canonical encoding that allows digital signatures and encryption, for example) or PER (to very efficiently transmit data over a radio channel, for example) can then be used as well as associated ASN.1 tools, or even specific encoding rules that are described in ECN.

Fast Infoset (Rec. ITU-T  X.891) specifies a representation of an instance of the W3C XML Information Set using ASN.1 binary encodings. This representation generally provides smaller encoding sizes and faster processing than a W3C XML representation. It provides the capability to encode XML content that is not described by a schema.

Fast Web Services (Rec. ITU-T X.892) is the term applied to the use of ASN.1 to provide message exchanges based on a SOAP envelope and WSDL specification of services that can have a higher transaction-processing rate and less bandwidth requirements than use of a character-based XML representation.

Rec. ITU-T X.893 "Generic Applications of ASN.1 - Fast Infoset and Fast Web Services Security" specifies the application of standard security methods to the Fast Infoset and Fast Web Services specifications.

In an open and international world such as the one of telecommunications and information technologies, one often needs to be able to reference an "object" in a unique and universal way. Usually, an object is a class of information (for example, a file format), rather than an instance of such a class (for example, an individual file).

Many standards define certain objects for which unambiguous identification is required. This is achieved by assignment of an object identifier (or OID) to an object in a way which makes the assignment available to interested parties. It is carried out by a Registration Authority.

The naming structure that has been chosen is a tree structure that allows the identification of objects in a local or international context, without being limited either by the registration authority, nor by the number of objects they can register. (The naming pattern is therefore similar to the one of the Internet domains and subdomains.) Each new node is associated with a name (a word beginning with a lowercase letter) and a number that will be used for data transfers. An OID is semantically an ordered list of object identifier components (or arcs).

Example: {joint-iso-itu-t(2) ds(5) attributeType(4) distinguishedName(49)}

The registration tree is managed in a completely decentralized way (a node gives full power to its children). The ASN.1 Project has set up a repository that gathers information about a lot of OIDs (including all of those that are defined in any ITU-T Recommendation), but it is impossible to collect in one repository all allocated OIDs (particularly world-wide, and within companies).

Supplementary information on operation of a country Registration Authority, and on known country Registration Authorities is available at http://www.oid-info.com/doc/country-OIDs.htm.

More background information on OIDs and Registration Authorities can be found in the final draft handbook “Object identifiers (OIDs) and their registration authorities” which is published in the six official UN languages and is available at http://www.itu.int/pub/T-HDB-LNG.4-2010.

The ASN.1 module database was initiated by France Telecom and donated to the ITU-T in November 2002.  The database currently contains over 733 ASN.1 modules corresponding to more than 200 ITU-T Recommendations. The maintenance of the database is handled by the Promotion, Edition and Production Department of the ITU TSB.

Implementations of the associated ITU-T Recommendations require an electronic format (using ASCII encoding) in order to directly process the formal definitions in current tools.  Obtaining an ASCII encoding from a printed or a post-script document involves re-typing, hinders speedy implementation and can introduce errors.  Having all ASN.1 modules (in ASCII format) in one place greatly eases implementation of the corresponding protocols.

The TSB validation process is as follows: firstly, the module is extracted from the Recommendation; a syntax and semantics check is then performed and, if errors are found, a communication process is established with the Editor and Rapporteur of the Recommendation to solve these errors.  The modules are checked as soon as possible after Consent is given.  This allows errors to be corrected during the publication phase and ensures that the published Recommendations are error-free.

Three validation tools were donated to the TSB: France Telecom donated Asnp, a syntax checker and HTML pretty-printer; OSS Nokalva donated their ASN.1 compiler; Opening Technologies donated their ASN.1/GDMO tool.

An agreement was reached with ISO, IETF, ITU-R and UPU in order to include any of their ASN.1 modules referenced by ITU-T Recommendations.

In cooperation with the Promotion, Edition and Production Department of the ITU TSB, the ASN.1 Project has established a database that contains a machine-processable copy of the current version of all ASN.1 modules that are included in ITU-T Recommendations (see previous section).

The ASN.1 Project has also been concentrating on a web-based repository of object identifiers (OIDs) and Registration Authorities as defined in the Rec. ITU-T  X.660 & X.670 series. France Telecom, in close liaison with the ASN.1 Project, is running a publicly available repository that contains information about more than 75,000 OIDs.

The ASN.1 Project has also helped many countries that wanted to have a national OID arc for their companies under {iso(1) member-body(2)} or {joint-iso-itu-t(2) country(16)}, and to delegate the Registration Authority to their ISO National Body and/or ITU Member State.

The new ITU-T Recommendation for UUID Generation and Registration (Rec. ITU-T  X.667) was approved in 2004. A UUID (Universally Unique Identifier) can be used for multiple purposes, from tagging objects with an extremely short lifetime, to reliably identifying very persistent objects across a network. France Telecom has prototyped the standard by implementing a UUID generator and donated it to the ITU-T. The UUID generator was installed on the ITU website in November 2004 and is freely usable. A connection with the OID repository was also developed: It offers an easy way to register a UUID as an OID.

TSB extended the module database with other formal descriptions used in ITU-T Recommendations, such as XML documents, GDMO definitions, and SNMP MIB modules.