Concise Binary Object Representation (CBOR) Tags for Date

Note

IETF specification defining a CBOR tag for a date text string, according to RFC 3339, intended for applications that need a textual date.

Summary

Purpose

IETF RFC 8943 (November 2020) defines two CBOR tags for representing a date without a time. CBOR (Concise Binary Object Representation) is a binary data format; its tags make it possible to extend its types RFC 8943, [Abstract](#abstract).

The second tag represents a date as a number of days since 1 January 1970 RFC 8943, [Abstract](#abstract).

Who it applies to

The RFC itself imposes nothing under eIDAS. It applies by reference to providers of person identification data (PID), who ensure that the PID issued comply with the annex to Implementing Regulation 2024/2977 Art. 3(3).

The reference concerns the encoding of PID in the ISO/IEC-mdoc format: the annex requires dates to be encoded in accordance with RFC 8943 Annex.

Key points

• Tag 1004. The annex requires the full-date attribute to be interpreted as #6.1004(tstr), that is, a text string carrying tag 1004, specified in RFC 8943 Annex. The RFC registers this tag for a UTF-8 text string in the full-date format of RFC 3339 RFC 8943, [2.1.](#section-2.1) [Concise Binary Object Representation (CBOR) Tags Registrations](#name-concise-binary-object-repre).
• The content of the string. The full-date attribute must contain a full-date string as specified in RFC 3339, in accordance with RFC 8943 Annex.
• The attributes concerned. Table 6 of the annex encodes the date of birth (birth_date) as full-date; the expiry date and the issuance date may be tdate or full-date Annex.
• A date, not an instant. Both tags represent dates without a time: time of day, time zone and leap seconds do not apply to them RFC 8943, [1.](#section-1) [Introduction](#name-introduction). The RFC in fact cites the date of birth on a driving licence as a use case RFC 8943, [1.1.](#section-1.1) [Calendar Dates](#name-calendar-dates).
• The second tag (100). It represents a number of days since the date 1 January 1970 RFC 8943, [2.1.](#section-2.1) [Concise Binary Object Representation (CBOR) Tags Registrations](#name-concise-binary-object-repre). The annex does not mention it Annex.
• Comparisons out of scope. Comparing a date with a date-time value is outside the scope of the RFC RFC 8943, [1.3.](#section-1.3) [Comparing Dates and Date/Time Values](#name-comparing-dates-and-date-ti).

Clauses referred to by the act

• The annex to Implementing Regulation 2024/2977 refers to tag 1004 and to the RFC for the encoding of dates, without a clause number Annex.
• The annex to Implementing Regulation 2024/2977 was replaced by Implementing Regulation 2026/1731 Implementing Regulation (EU) 2026/1731; this summary cites the consolidated version that incorporates it.

Links

• Act that makes it applicable: Implementing Regulation 2024/2977 Implementing Regulation (EU) 2024/2977 — consolidated version of 11/08/2026.
• Related standards: RFC 3339, date-time format RFC 3339; RFC 8949, CBOR RFC 8949; RFC 8610, CDDL notation RFC 8610.
• Learning path: step 3, the European wallet.

Written by Asphalia.