draft-ietf-cbor-date-tag-04.txt   draft-ietf-cbor-date-tag-05.txt 
CBOR Working Group M. Jones CBOR Working Group M. Jones
Internet-Draft A. Nadalin Internet-Draft A. Nadalin
Intended status: Standards Track Microsoft Intended status: Standards Track Microsoft
Expires: January 15, 2021 J. Richter Expires: January 17, 2021 J. Richter
pdv Financial Software GmbH pdv Financial Software GmbH
July 14, 2020 July 16, 2020
Concise Binary Object Representation (CBOR) Tags for Date Concise Binary Object Representation (CBOR) Tags for Date
draft-ietf-cbor-date-tag-04 draft-ietf-cbor-date-tag-05
Abstract Abstract
The Concise Binary Object Representation (CBOR, RFC 7049) is a data The Concise Binary Object Representation (CBOR, RFC 7049) is a data
format whose design goals include the possibility of extremely small format whose design goals include the possibility of extremely small
code size, fairly small message size, and extensibility without the code size, fairly small message size, and extensibility without the
need for version negotiation. need for version negotiation.
In CBOR, one point of extensibility is the definition of CBOR tags. In CBOR, one point of extensibility is the definition of CBOR tags.
RFC 7049 defines two tags for time: CBOR tag 0 (RFC 3339 date/time RFC 7049 defines two tags for time: CBOR tag 0 (RFC 3339 date/time
string) and tag 1 (Posix "seconds since the epoch"). Since then, string) and tag 1 (Posix "seconds since the epoch"). Since then,
additional requirements have become known. This specification additional requirements have become known. This specification
defines a CBOR tag for an RFC 3339 date text string, for applications defines a CBOR tag for an RFC 3339 date text string, for applications
needing a textual date representation within the Gregorian calendar needing a textual date representation within the Gregorian calendar
without a time. It also defines a CBOR tag for days since the date without a time. It also defines a CBOR tag for days since the date
1970-01-01 in the Gregorian calendar for applications needing a 1970-01-01 in the Gregorian calendar for applications needing a
numeric date representation without a time. It is intended as the numeric date representation without a time. This specification is
reference document for the IANA registration of the CBOR tags intended as the reference document for IANA registration of the CBOR
defined. tags defined.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 15, 2021. This Internet-Draft will expire on January 17, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Calendar Dates . . . . . . . . . . . . . . . . . . . . . 3 1.1. Calendar Dates . . . . . . . . . . . . . . . . . . . . . 3
1.2. Comparing Dates . . . . . . . . . . . . . . . . . . . . . 3 1.1.1. Example Date Representations . . . . . . . . . . . . 3
1.3. Comparing Dates and Times . . . . . . . . . . . . . . . . 3 1.2. Comparing Dates . . . . . . . . . . . . . . . . . . . . . 4
1.3. Comparing Dates and Date/Time Values . . . . . . . . . . 4
2. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 2. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
2.1. Concise Binary Object Representation (CBOR) Tags 2.1. Concise Binary Object Representation (CBOR) Tags
Registrations . . . . . . . . . . . . . . . . . . . . . . 4 Registrations . . . . . . . . . . . . . . . . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . 4 3. Security Considerations . . . . . . . . . . . . . . . . . . . 5
4. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Normative References . . . . . . . . . . . . . . . . . . 4 4.1. Normative References . . . . . . . . . . . . . . . . . . 5
4.2. Informative References . . . . . . . . . . . . . . . . . 5 4.2. Informative References . . . . . . . . . . . . . . . . . 5
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 5 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 5
Document History . . . . . . . . . . . . . . . . . . . . . . . . 5 Document History . . . . . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
The Concise Binary Object Representation (CBOR) [RFC7049] provides The Concise Binary Object Representation (CBOR) [RFC7049] provides
for the interchange of structured data without a requirement for a for the interchange of structured data without a requirement for a
pre-agreed schema. RFC 7049 defines a basic set of data types, as pre-agreed schema. RFC 7049 defines a basic set of data types, as
well as a tagging mechanism that enables extending the set of data well as a tagging mechanism that enables extending the set of data
types supported via an IANA registry. types supported via an IANA registry.
This specification defines a CBOR tag for a text string representing This specification defines a CBOR tag for a text string representing
skipping to change at page 3, line 18 skipping to change at page 3, line 19
Julian Date minus 40587. Julian Date minus 40587.
Note that since both tags are for dates without times, times of day, Note that since both tags are for dates without times, times of day,
time zones, and leap seconds are not applicable to these values. time zones, and leap seconds are not applicable to these values.
These tags are both for representations of Gregorian calendar dates. These tags are both for representations of Gregorian calendar dates.
1.1. Calendar Dates 1.1. Calendar Dates
Calendar dates are used for numerous human use cases, such as marking Calendar dates are used for numerous human use cases, such as marking
the dates of significant events. For instance, John Lennon was born the dates of significant events. For instance, John Lennon was born
on October 9, 1940 and died on December 8, 1980. One such common use on October 9, 1940 and died on December 8, 1980. One such use case
case is driver's licenses, which typically include a date of birth. is driver's licenses, which typically include a date of birth. The
The dates used in this specification use the Gregorian calendar, as dates used in this specification use the Gregorian calendar, as do
do those in RFC 3339 [RFC3339]. The time zones and actual times of those in RFC 3339 [RFC3339]. The time zones and actual times of
these events are intentionally not represented in the calendar date. these events are intentionally not represented in the calendar date.
The epoch chosen for the second tag, which represents days since the The epoch chosen for the second tag, which represents days since the
Gregorian calendar date 1970-01-01, is related to the IEEE Std Gregorian calendar date 1970-01-01, is related to the IEEE Std
1003.1, 2013 Edition [POSIX.1] time epoch 1970-01-01T00:00:00Z UTC 1003.1, 2013 Edition [POSIX.1] time epoch 1970-01-01T00:00:00Z UTC
only insofar as both contain the date 1970-01-01. This should not be only insofar as both contain the date 1970-01-01. This should not be
construed as indicating that dates using this tag represent either a construed as indicating that dates using this tag represent either a
specific time of day and/or time zone. specific time of day and/or time zone.
The day of the week (Sunday, Monday, Tuesday, etc.) is not explicitly The day of the week (Sunday, Monday, Tuesday, etc.) is not explicitly
represented in either of these date formats. However, deterministic represented in either of these date formats. However, deterministic
algorithms that are beyond the scope of this specification can be algorithms that are beyond the scope of this specification can be
used to derive the day of the week in the Gregorian calendar from used to derive the day of the week in the Gregorian calendar from
dates represented in both of these formats. dates represented in both of these formats.
1.1.1. Example Date Representations
This table contains example representations for dates using both
tags.
+------------------+--------------+---------+
| Date | Tag 1004 | Tag 100 |
+------------------+--------------+---------+
| October 9, 1940 | "1940-10-09" | -10676 |
| December 8, 1980 | "1980-12-08" | 3994 |
+------------------+--------------+---------+
1.2. Comparing Dates 1.2. Comparing Dates
Comparison of dates in "full-date" format can be accomplished by Comparison of dates in "full-date" format can be accomplished by
normal string comparison, since by design, the digits representing normal string comparison, since by design, the digits representing
the date are in fixed format and ordered from most significant to the date are in fixed format and ordered from most significant to
least significant. Comparison of numeric dates representing days least significant. Comparison of numeric dates representing days
since 1970-01-01 can be performed by normal integer comparison. since 1970-01-01 can be performed by normal integer comparison.
Comparison of dates in other formats or using other calendars require Comparison of dates in other formats or using other calendars require
conversions that are beyond the scope of this specification. conversions that are beyond the scope of this specification.
1.3. Comparing Dates and Times Note that different dates may correspond to the same moment in time,
depending upon the time zone in which the date was determined. For
instance, at many times of the day, a conference call occurring on a
particular date in Japan will simultaneously occur on the previous
date in Hawaii; at many times of the day, Japan's Friday corresponds
with Hawaii's Thursday.
Comparing dates with times is beyond the scope of this specification. 1.3. Comparing Dates and Date/Time Values
That said, if a date is augmented with a time zone and time of day,
comparing that augmented date with other times becomes possible. For Comparing dates with date/time values, which represent a particular
instance, if one were to augment John Lennon's birth date of October moment in time, is beyond the scope of this specification. That
9, 1940 with the time of day and time zone of his birth, then it said, if a date is augmented with a time zone and time of day, a
would be possible to derive a time at which he was born that could be specific date/time value can be determined and comparing that date/
compared with other times. time value to others becomes possible. For instance, if one were to
augment John Lennon's birth date of October 9, 1940 with the time of
day and time zone of his birth, then it would be possible to derive a
date/time at which he was born that could be compared with other
date/time values.
2. IANA Considerations 2. IANA Considerations
2.1. Concise Binary Object Representation (CBOR) Tags Registrations 2.1. Concise Binary Object Representation (CBOR) Tags Registrations
This section registers the following values in the IANA "Concise This section registers the following values in the IANA "Concise
Binary Object Representation (CBOR) Tags" registry [IANA.cbor-tags]. Binary Object Representation (CBOR) Tags" registry [IANA.cbor-tags].
o Tag: 1004 (value requested) o Tag: 1004
o Data Item: UTF-8 text string o Data Item: UTF-8 text string
o Semantics: RFC 3339 full-date string o Semantics: RFC 3339 full-date string
o Reference: [[ this specification ]] o Reference: [[ this specification ]]
o Tag: 100 (ASCII 'd') (value requested) o Tag: 100 (ASCII 'd')
o Data Item: Unsigned or negative integer o Data Item: Unsigned or negative integer
o Semantics: Number of days since the epoch date 1970-01-01 o Semantics: Number of days since the epoch date 1970-01-01
o Reference: [[ this specification ]] o Reference: [[ this specification ]]
3. Security Considerations 3. Security Considerations
The security considerations of RFC 7049 apply; the tags introduced The security considerations of RFC 7049 apply; the tags introduced
here are not expected to raise security considerations beyond those. here are not expected to raise security considerations beyond those.
A date, of course, has significant security considerations. These A date, of course, has significant security considerations. These
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Thanks to these people for reviews of the specification: Henk Thanks to these people for reviews of the specification: Henk
Birkholz, Carsten Bormann, Thiago Macieira, Francesca Palombini, Birkholz, Carsten Bormann, Thiago Macieira, Francesca Palombini,
Michael Richardson, Jim Schaad, Juergen Schoenwaelder, and Dale Michael Richardson, Jim Schaad, Juergen Schoenwaelder, and Dale
Worley. Worley.
Document History Document History
[[ to be removed by the RFC Editor before publication as an RFC ]] [[ to be removed by the RFC Editor before publication as an RFC ]]
-05
o Incorporated additional suggestions by Carsten Bormann and Juergen
Schoenwaelder.
-04 -04
o Addressed shepherd comments by Francesca Palombini. o Addressed shepherd comments by Francesca Palombini.
o Addressed additional review comments by Jim Schaad and Michael o Addressed additional review comments by Jim Schaad and Michael
Richardson. Richardson.
-03 -03
o Added statement that these tags are both for representations of o Added statement that these tags are both for representations of
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