Reference record for OID 2.25

UUIDs are an octet string of 16 octets (128 bits). The 16 octets can be interpreted as an unsigned integer encoding, and the resulting integer value can be used as a subsequent arc of {joint-iso-itu-t uuid(25)} (or 2.25) in the OID tree without formal registration (in particular on this web site). This enables users to generate OIDs without any registration procedure.

Note. It was previously allowed to register UUIDs on this web site (according to the 2008 edition of Rec. ITU-T X.667 | ISO/IEC 9834-8) but this feature is not offered any more since the 2012 edition: UUIDs can in all cases be appended after the 2.25 arc without registration.

See more information on UUIDs. UUID generators are available from the ITU and from Daniel Marschall.

It is important to note that identical UUID values might be used as subsequent arcs of this OID (without formal registration), although the probability of this occurring is very small. The probability is increased if UUIDs are generated from MD5 hash values or pseudo-random numbers, rather than from SHA-1 hash values and cryptographic-quality random numbers.

Note: There are 2 ways of producing a URN for a particular UUID:
- use the "urn:uuid:" prefix as explained in clause 8 of Rec. ITU-T X.667 | ISO/IEC 9834-8.
- use the "urn:oid:2.25." prefix according to IETF RFC 3061 (but this alternative is not recommended by Rec. ITU-T X.667 | ISO/IEC 9834-8).

This OID arc was allocated by clause 7 of Rec. ITU-T X.667 (2005) | ISO/IEC 9834-8:2005: "Procedures for the operation of OSI Registration Authorities - Generation and Registration of Universally Unique Identifiers (UUIDs) and their Use as ASN.1 Object Identifier Components".