[urn] Request for a Namespace Registration for Unique (Vaccination) Certificate Identifier

[Dirk-Willem van Gulik <[e-mail]>]

Namespace Registration for Unique (Vaccination) Certificate Identifier

Namespace ID: UVCI (requested of IANA, case insensitive)
 
     Version: 1.01

        Date: 2021-07-28

  Registrant: eHealth Network 
        
Post address: The eHealth Network,
              eHealth Network Secretariat
        p/a:  Directorate-General for Health and Food Safety
              European Commission
              1049 Bruxelles/Brussel
              Belgium

       eMail: eHEALTH-NETWORK(at)ec(dot)europa(dot)eu

Requesting entity is a network of national authorities responsible for 
eHealth established pursuant to Article 14 of Directive 2011/24/EU and 
the European Commission Implementing Decision 2019/1765. It essentially 
consists of the representatives of Ministries of Health or the equivalent 
national Public Health Authorities of the EU and EEA Member States.

Overview: 

In response to the COVID-19 Pandemic the public health authorities of 
the EU Member States collaborated on a single-purpose, cross-border, 
interoperable, digital health certificate specific to COVID-19[1]. 

This certificate takes the form of a paper or digital document, that 
may also be displayed in a mobile app. In its digital version[2] it is 
a QR code that contains Base45 encoded, Zlib compressed, digitally 
signed (COSE) structured block (CBOR) of medical and citizen 
identifying data. An out of band trust management mechanism provides 
the ECC public keys for (offline) signare validation and key revocation.

Regulation 2021/953[4] prohibits the storage or retention of data 
following verification. The exchange of Personally Identifiable 
Information is not necessary for the purposes of the Regulation. 
However in certain cases (e.g. to prevent or detect fraud) it may still 
be essential to exchange lists of revoked certificates.

For this reason the design[2] calls for a Unique (Vaccination) 
Certificate Identifier (UVCI) that uniquely identifies a specific test, 
vaccination or recovery certificate. The format chosen for this UVCI is 
that of a Universal Resource name or URN that follows the best current 
practices (BCP: 66, RFC8141). The NID selected is ‘UVCI’.

The NSS[3 annex 2] consists of a version and country/issuing entity 
prefix followed by an opaque unique string, an opaque unique string 
prefixed by a regional Issuing Entity or a triplet of entity, 
vaccination and again an opaque unique string. This latter format never 
saw any use  - and may be dropped from future versions of the standard.

When used in print it may be followed by a ‘#’ and a LUHN based 
checksum.

To further ease of reliable manual entry the character set is limited 
to A-Z and 0-9, case insensitive. Elements are separated by a slash 
within the main block; and a colon for the version and country.

It is up to each Member State to manage this space well and ensure that 
the URN as a whole stays unique. Some countries have opted for a single 
space for the whole country; others have delegated parts of the space 
to nations or regions within the member state; each with their own 
prefix or range. 

Examples are:

        urn:uvci:01:BG:UFR5PLGKU8WDSZK7#0
        urn:uvci:01:PT:SPMS/TRC01234567890123456#1
        URN:UVCI:01:PL:3/655052DD53A649E897FA10AC9C175654
        URN:UvCI:01:NL:2WC7BASRIALG5FBUHLNNNX3A42#:
        URN:UVCI:01:GB:112739138279141HSFJYRDT#R
        
The syntax of the NSS (i.e. the string past the URN prefix and NID, 
‘urn:uvci:’) is defined in [3]; and can be paraphrased as:

        VERSION ':' COUNTRY ':' C_NSS [ '#' LUHN ]

With:

        VERSION      version number. Currently set to the string '01'.

        COUNTRY      Issuing entity, in general a country. The 
                     ISO3166-1 character code must be used. Other codes
                     (3 characters, and longer, e.g. 'UNHCR' or 'WHO' 
                     are reserved for future use))

        C_NSS        Country specific/managed/delegated NNS

        LUHN         OPTIONAL checksum for print.

The country specific NSS, C_NSS is one of the following 3 formats:

1)      ALPHANUMSTR 

2)      ISSUER '/' ALPHANUMSTR  

3)      ISSUER '/' VACCINE '/' ALPHANUMSTR

With:

        ALPHANUMSTR  A string consisting of A-Z, 0-9 (case insensitive).

        ISSUER       An ALPHANUMSTR that denotes an issuer specific 
                     to the Country.

        VACCINE      An ALPHANUMSTR that denotes a vaccine or similar
                     sub grouping.

None of these strings can be empty. All are case insensitive (as they 
may be entered from a printed document). 

Appendix 1 contains a ABNF of above.

Exceptions and Legacy:

At this time there are two known deviations. 

Firstly - there are two suffixes in use; the original UVCI and a newer 
UCI. The reason for this was that during the design and first roll-outs 
the pandemic evolved; and it became clear that not just vaccination 
certificates would be issued - but also test and recovery certificates. 
So some countries started to use the more generic UCI.

However - UCI is already in use (RFC4179). So this newer UCI will need 
to be phased out; with UVCI remaining (only 1 or 2 countries appear to 
use this).

Secondly - a few countries have issued abbreviated UVCIs; which lack 
the URN:UVCI prefix. An example of this is: "01/LU/2O1I84U8U12I5#UK".

Rules for Lexical Equivalence:

The URN should be compared case-insensitive in its entirety; from (and 
including the ‘URN:’ up and until, but not including the optional ‘#’ 
and optional checksum. The optional checksum is not part  of the URN 
(or its comparison). It is however recommended when the URN is printed.

If the context allows for it - the removal of the 'urn:uvci' from the 
printed (and human entered) string is allowed. And should be restored 
prior to digital handling, comparisons and transmission (e.g. in a 
QR code).

Assignment:

Assignment of the URNs is delegated to each of the member states; who 
may delegate this within their state - e.g. to a regional health 
authority or to a nation within their state. The Secretariat of the 
eHealth Network maintains a list of contacts for each State.

Each Member State is responsible for managing this space well and 
keeping the entries overall unique (some States may have multiple 
ISO3166-1 entries; these, and the version number, are considered an 
integral part of the identifier, also for uniqueness purposes).

Security and Privacy:

This URN is classified as a piece of Personally Identifiable 
Information (it references a medical 'fact' about a person; about 
the traveler) and, for this reason subject to the regulation[4] 
and national law.

Interoperability:  

The UVCI is a unique and persistent identifier.  An UVCI, once it has 
been assigned, must never be reused.

There are no characters in UVCI which would require percent-encoding. 

Persistence of the resources: 

The UVCI pertains to a specific (medical) record about a specific 
person’s vaccination, test or recovery at event level [1,2]. This 
record is subject to national legislation and regulation.

Persistence of the identifier: 

The UVCI as an identifier is persistent in the sense that once 
assigned, an UVCI will never be reassigned. 

Resolution:  

For URN resolution purposes, all elements up to, but not including the 
'#' and checksum must be taken into account.

Persistence of the remote/public resolvers: 

At this time there are no remote or public resolvers -- the cross border
continuity of care scenario referenced in below documents has not been 
implemented at this time. No timeline (or a decision) to implement such
has been taken.

Documentation/References:  

1: COMMISSION IMPLEMENTING DECISION (EU) 2021/1073 of 28 June 2021 
   laying down technical specifications and rules for the implementation 
   of the trust framework for the EU Digital COVID Certificate established 
   by Regulation (EU) 2021/953 of the European Parliament and of the 
   Council, <http://data.europa.eu/eli/reg/2021/953/oj>

2: eHealth Network, Guidelines on Technical Specifications for EU 
   Digital COVID Certificates, Volumes 1-5, 
   <https://ec.europa.eu/health/ehealth/key_documents_en>

3: eHealth Network Guidelines on verifiable vaccination certificates - 
   basic interoperability elements, Release 2, 2021-03-12,
   <https://ec.europa.eu/health/ehealth/key_documents_en>

4: Regulation (EU) 2021/953 on a framework for the issuance, 
   verification and acceptance of interoperable COVID-19 vaccination, 
   test and recovery certificates (EU Digital COVID Certificate) to 
   facilitate free movement during the COVID-19 pandemic, 
   <https://eur-lex.europa.eu/eli/reg/2021/953/oj>

Additional Information:  

    See: https://ec.europa.eu/health/ehealth/key_documents_en

Revision Information:  

    Version 1.00 -- This registration is based on the 2021/1073 of 
                    28 June 2021 implementing decision. (2021/07/20)

    Version 1.01 -- Add legacy/exception example (LU), several typos
                    Fixed, URLs added (2021/07/28).

Appendix 1 - RFC5234 Augmented BNF of the URN

This is a non-normative ABNF derived from [2,3]. The definitions for 
ALPHA and DIGIT are from RFC5234. The NID or NSS are conform RFC8141.

       URN = "URN" URN_SEP NID URN_SEP NSS

       NID = "UVCI"; note that an ABNF string is case _in_ sensitive.

       NSS =  VERSION NSS_SEP COUNTRY NSS_SEP C_NSS [ CRC_SEP LUHN ]

   VERSION = 2*DIGIT  ; only the value "01" is defined at this time.

   COUNTRY = 2*ALPHA [ *ALPHA ] ; only 2 char from ISO 3166-1 defined 
                                ; at this time.

     C_NSS = OPTION1 / OPTION2 / OPTION 3

   OPTION1 = AZ09STR 

   OPTION2 = ISSUER CNTRY_SEP AZ09STR

   OPTION3 = ISSUER CNTRY_SEP VACCINE CNTRY_SEP AZ09STR ; not observed 
                                                        ; in active use.

   URN_SEP = ":"

   NSS_SEP = ":"

 CNTRY_SEP = "/"

   CRC_SEP = "#"

      LUHN = 1*ALPHANUM

    ISSUER = AZ09STR

   VACCINE = AZ09STR

   AZ09STR = 1*AZ09 [ *AZ09 ]; non empty arbitrary len alpha numeric 
                             ; ascii string

       AZ09 = ALPHA / DIGIT

Although commonly used software imposes a limit of around 2kByte on 
the length of a URI, implementers are advised to stay below the 60 
characters for usability reasons (they may need to be routinely entered 
from a paper travel document by hand).