object identifier

An official, globally unique name for a thing, written as a sequence of integers (which are formed and assigned as defined in the ASN.1 standard) and used to reference the thing in abstract specifications and during negotiation of security services in a protocol.

"A value (distinguishable from all other such values) [that] is associated with an object." [X680]

Tutorial: Objects named by OIDs are leaves of the object identifier tree (which is similar to but different from the X.500 Directory Information Tree). Each arc (i.e., each branch of the tree) is labeled with a non-negative integer. An OID is the sequence of integers on the path leading from the root of the tree to a named object.

The OID tree has three arcs immediately below the root: {0} for use by ITU-T, {1} for use by ISO, and {2} for use by both jointly. Below ITU-T are four arcs, where {0 0} is for ITU-T recommendations. Below {0 0} are 26 arcs, one for each series of recommendations starting with the letters A to Z, and below these are arcs for each recommendation. Thus, the OID for ITU-T Recommendation X.509 is {0 0 24 509}. Below ISO are four arcs, where {1 0 }is for ISO standards, and below these are arcs for each ISO standard. Thus, the OID for ISO/IEC 9594-8 (the ISO number for X.509) is {1 0 9594 8}.

ANSI registers organization names below the branch {joint-iso- ccitt(2) country(16) US(840) organization(1) gov(101) csor(3)}. The NIST CSOR records PKI objects below the branch {joint-iso-itu- t(2) country(16) us(840) organization (1) gov(101) csor(3)}. The U.S. DoD registers INFOSEC objects below the branch {joint-iso- itu-t(2) country(16) us(840) organization(1) gov(101) dod(2) infosec(1)}.

The IETF's Public-Key Infrastructure (pkix) Working Group registers PKI objects below the branch {iso(1) identified- organization(3) dod(6) internet(1) security(5) mechanisms(5) pkix(7)}. [R3280]