Internet-Draft RDAP Reverse search August 2023
Loffredo & Martinelli Expires 2 March 2024 [Page]
Workgroup:
Registration Protocols Extensions
Internet-Draft:
draft-ietf-regext-rdap-reverse-search-25
Published:
Intended Status:
Standards Track
Expires:
Authors:
M. Loffredo
IIT-CNR/Registro.it
M. Martinelli
IIT-CNR/Registro.it

Registration Data Access Protocol (RDAP) Reverse Search

Abstract

The Registration Data Access Protocol (RDAP) does not include query capabilities for finding the list of domains related to a set of entities matching a given search pattern. Considering that an RDAP entity can be associated with any defined object class and other relationships between RDAP object classes exist, a reverse search can be applied to other use cases besides the classic domain-entity scenario. This document describes an RDAP extension that allows servers to provide a reverse search feature based on the relationship defined in RDAP between an object class for search and any related object class. The reverse search based on the domain-entity relationship is treated as a particular case.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on 2 March 2024.

Table of Contents

1. Introduction

The protocol described in this specification aims to extend the RDAP query capabilities and response to enable reverse search based on the relationships defined in RDAP between an object class for search and a related object class. The reverse search based on the domain-entity relationship is treated as a particular case of such a generic model.

RDAP providers willing to implement this specification should carefully consider its implications on the efficiency (see Section 10), the security (see Section 14) and the compliance with privacy regulations (see Section 13) of their RDAP service.

1.1. Background

Reverse Whois is a service provided by many web applications that allows users to find domain names owned by an individual or a company starting from the owner's details, such as name and email. Even if it has been considered useful for some legal purposes (e.g. uncovering trademark infringements, detecting cybercrimes), its availability as a standardized Whois [RFC3912] capability has been objected to for two main reasons, which now don't seem to conflict with an RDAP implementation.

The first objection concerns the potential risks of privacy violation. However, the domain name community is considering a new generation of Registration Directory Services [ICANN-RDS1] [ICANN-RDS2] [ICANN-RA], which provide access to sensitive data under some permissible purposes and in accordance with appropriate policies for requestor accreditation, authentication and authorization. RDAP's reliance on HTTP means that it can make use of common HTTP-based approaches to authentication and authorization, making it more useful than Whois in the context of such directory services. Since RDAP consequently permits a reverse search implementation complying with privacy protection principles, this first objection is not well-founded.

The second objection to the implementation of a reverse search capability has been connected with its impact on server processing. However, the core RDAP specifications already define search queries, with similar processing requirements, so the basis of this objection is not clear.

Reverse searches, such as finding the list of domain names associated with contacts or nameservers, may be useful to registrars as well. Usually, registries adopt out-of-band solutions to provide results to registrars asking for reverse searches on their domains. Possible reasons for such requests are:

  • the loss of synchronization between the registrar database and the registry database;

  • the need for such data to perform bulk Extensible Provisioning Protocol (EPP) [RFC5730] updates (e.g. changing the contacts of a set of domains, etc.).

Currently, RDAP does not provide any means for a client to search for the collection of domains associated with an entity [RFC9082]. A query (lookup or search) on domains can return the array of entities related to a domain with different roles (registrant, registrar, administrative, technical, reseller, etc.), but the reverse operation is not allowed. Only reverse searches to find the collection of domains related to a nameserver (ldhName or ip) can be requested. Since an entity can be in relationship with any RDAP object [RFC9083], the availability of a reverse search as largely intended can be common to all the object classes allowed for search. Through a further step of generalization, the meaning of reverse search in the RDAP context can be extended to include any query for retrieving all the objects in relationship with another matching a given search pattern.

1.2. Conventions Used in This Document

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

2. Reverse Search Path Segment Specification

A generic reverse search path is described by the syntax:

{searchable-resource-type}/reverse_search/{related-resource-type}?<search-condition>

The path segments are defined as in the following:

"searchable-resource-type":

it MUST be one of the resource types for search defined in Section 3.2 of [RFC9082] (i.e. "domains", "nameservers" and "entities") or a resource type extension;

"related-resource-type":

it MUST be one of the resource types for lookup defined in Section 3.1 of [RFC9082] (i.e. "domain", "nameserver", "entity", "ip" and "autnum") or a resource type extension;

"search-condition":
a sequence of "property=search pattern" predicates separated by the ampersand character ('&', US-ASCII value 0x0026).

While related-resource-type is defined as having one of a number of different values, the only reverse searches defined in this document are for a related-resource-type of "entity". Reverse searches for the other resource types specified in [RFC9082] and resource type extensions may be defined by future documents.

3. Reverse Search Definition

Based on the content of Section 2, defining a reverse search means to define the triple <searchable resource type, related resource type, property> and the mapping with the corresponding RDAP object member. The mapping is done through the use of a JSONPath expression [I-D.ietf-jsonpath-base]. Reverse searches are registered in the Reverse Search registry (see Section 12.2.3), whereas reverse search mappings are registered in the Reverse Search Mapping registry (see Section 12.2.4). The reason for having two registries is that it may be possible for a single type of reverse search to rely on different members, depending on the server's configuration (see Section 5).

All of the reverse searches defined by this document (see Section 8) have property names that are the same as the name of the RDAP object member that is the subject of the search. For example, the reverse search with the property name "fn" relies on the value of the "fn" member inside the jCard of an entity object. However, it is not necessary that these two names be the same. In particular, remapping of searches as part of the deprecation of an existing member (see Section 5) will typically lead to a member with a different name being used for the search.

Servers MUST NOT provide or implement reverse searches or reverse search mappings that are not registered with IANA.

4. Reverse Search Properties Discovery

Servers complying with this specification MUST extend the help response [RFC9083] with the "reverse_search_properties" member which contains an array of objects with the following mandatory child members:

"searchableResourceType":
the searchable resource type of the reverse search query as defined in Section 2;
"relatedResourceType":
the related resource type of the reverse search query as defined in Section 2;
"property":
the reverse search property used in the predicate of the reverse search query as defined in Section 2;

An example of the help response including the "reverse_search_properties" member is shown in Figure 2.

5. Reverse Search Properties Mapping

To permit clients to determine the member used by the server for a reverse search, servers MUST detail the mapping that is occurring by adding the "reverse_search_properties_mapping" member to the topmost object of a reverse search response. This data is included in the search response, rather than in the help response, because it may differ depending on the query that is sent to the server.

Documents that deprecate or restructure RDAP responses such that a registered reverse search is no longer able to be used MUST either note that the relevant reverse search is no longer available (in the case of deprecation) or describe how to continue supporting the relevant search by adding another mapping for the reverse search property (in the case of restructuring).

The "reverse_search_properties_mapping" member contains an array of objects with the following mandatory child members:

"property":
the reverse search property used in the predicate of the current query as defined in Section 2;
"propertyPath":
the JSONPath expression of the object member (or members) corresponding to the reverse search property.

The searchable and the related resource types are derived from the query, so there is no need to include them in addition to the property in this member.

This member MUST be included for all properties used in the search, regardless of whether that property has multiple registered mappings as at the time of the search, because new mappings may be registered at any time.

When applied to an object, the JSONPath expression MUST produce a list of values, each of which is a JSON number or string.

An example of a reverse search response including the "reverse_search_properties_mapping" member is shown in Figure 3.

6. Reverse Search Response Specification

Reverse search responses use the formats defined in section 8 of [RFC9083], which correspond to the searchable resource types defined in Section 2.

7. Reverse Search Query Processing

To process a reverse search, the server returns the objects from its data store that are of type searchable-resource-type and that match each of the predicates from the search conditions. To determine whether an object matches a predicate, the server:

A search pattern matches a value where it equals the string representation of the value, or where it is a match for the value in accordance with the partial string matching behaviour defined in section 4.1 of [RFC9082].

Objects are only included in the search results if they satisfy all included predicates. This includes predicates that are for the same property: it is necessary in such a case for the related object to match against each of those predicates.

Servers MUST return an HTTP 501 (Not Implemented) [RFC9110] response to inform clients of unsupported reverse searches.

Based on their policy, servers MAY restrict how predicates are used to make a valid search condition, by returning a 400 (Bad Request) response when a problematic request is received.

A given reverse search or reverse search mapping MAY define additional or alternative search behaviour past that set out in this section.

8. Reverse Searches Based on Entity Details

Since in RDAP, an entity can be associated with any other object class, the most common kind of reverse search is one based on an entity's details. Such reverse searches arise from the query model by setting the related resource type to "entity".

By selecting a specific searchable resource type, the resulting reverse search aims at retrieving all the objects (e.g. all the domains) that are related to any entity object matching the search conditions.

This section defines the reverse search properties servers SHOULD support for the domain, nameserver, and entity searchable resource types and the entity related resource type:

Reverse search property:
role
RDAP member path:
$.entities[*].roles
Reference:
Section 10.2.4 of [RFC9083]
Reverse search property:
handle
RDAP member path:
$.entities[*].handle
Reference:
Section 5.1 of [RFC9083]
Reverse search property:
fn
RDAP member path:
$.entities[*].vcardArray[1][?(@[0]=='fn')][3]
Reference:
Section 6.2.1 of [RFC6350]
Reverse search property:
email
RDAP member path:
$.entities[*].vcardArray[1][?(@[0]=='email')][3]
Reference:
Section 6.4.2 of [RFC6350]

The presence of a predicate on the reverse search property "role" means that the RDAP response property "roles" MUST contain at least the specified role.

The last two properties are related to jCard elements [RFC7095], but the field references are to vCard [RFC6350], since jCard is the JSON format for vCard.

Examples of reverse search paths based on the domain-entity relationship are presented in Figure 1.

 /domains/reverse_search/entity?handle=CID-40*&role=technical

 /domains/reverse_search/entity?fn=Bobby*&role=registrant

 /domains/reverse_search/entity?handle=RegistrarX&role=registrar
Figure 1: Examples of reverse search queries

An example of the help response including the reverse search properties supported is shown below.

   {
     "rdapConformance": [
       "rdap_level_0",
       "reverse_search"
     ],
     ...
     "reverse_search_properties": [
       {
         "searchableResourceType": "domains",
         "relatedResourceType": "entity",
         "property": "fn"
       },
       {
         "searchableResourceType": "domains",
         "relatedResourceType": "entity",
         "property": "handle"
       },
       {
         "searchableResourceType": "domains",
         "relatedResourceType": "entity",
         "property": "email"
       },
       {
         "searchableResourceType": "domains",
         "relatedResourceType": "entity",
         "property": "role"
       }
     ],
     ...
   }

Figure 2: An example of help response including the "reverse_search_properties_mapping" member

An example of a response including the mapping that is occurring for the first reverse search in Figure 1 is shown below.


   {
     "rdapConformance": [
       "rdap_level_0",
       "reverse_search"
     ],
     ...
     "reverse_search_properties_mapping": [
       {
         "property": "handle",
         "propertyPath": "$.entities[*].handle"
       },
       {
         "property": "role",
         "propertyPath": "$.entities[*].roles"
       }
     ],
     ...
   }

Figure 3: An example of an RDAP response including the "reverse_search_properties" member

9. RDAP Conformance

Servers complying with this specification MUST include the value "reverse_search" in the rdapConformance property of the help response [RFC9083] and any other response including the "reverse_search_properties_mapping" member. The information needed to register this value in the "RDAP Extensions" registry is described in Section 12.1.

10. Implementation Considerations

To limit the impact of processing the search predicates, servers are RECOMMENDED to make use of techniques to speed up the data retrieval in their underlying data store such as indexes or similar. In addition, risks with respect to performance degradation or result set generation can be mitigated by adopting practices used for standard searches, e.g. restricting the search functionality, limiting the rate of search requests according to the user's authorization, truncating and paging the results [RFC8977], and returning partial responses [RFC8982].

11. Implementation Status

NOTE: Please remove this section and the reference to RFC 7942 prior to publication as an RFC.

This section records the status of known implementations of the protocol defined by this specification at the time of posting of this Internet-Draft, and is based on a proposal described in [RFC7942]. The description of implementations in this section is intended to assist the IETF in its decision processes in progressing drafts to RFCs. Please note that the listing of any individual implementation here does not imply endorsement by the IETF. Furthermore, no effort has been spent to verify the information presented here that was supplied by IETF contributors. This is not intended as, and must not be construed to be, a catalog of available implementations or their features. Readers are advised to note that other implementations may exist.

According to RFC 7942, "this will allow reviewers and working groups to assign due consideration to documents that have the benefit of running code, which may serve as evidence of valuable experimentation and feedback that have made the implemented protocols more mature. It is up to the individual working groups to use this information as they see fit".

11.1. IIT-CNR/Registro.it RDAP Server

  • Responsible Organization: Institute of Informatics and Telematics of National Research Council (IIT-CNR)/Registro.it

  • Location: https://rdap.pubtest.nic.it/

  • Description: This implementation includes support for RDAP queries using data from the public test environment of .it ccTLD. Reverse search is allowed to authenticated users. Registrar users are allowed to perform reverse searches on their own domains and contacts. This is achieved by adding an implicit predicate to the search condition.

  • Level of Maturity: This is an "alpha" test implementation.

  • Coverage: This implementation includes all of the features described in this specification.

  • Contact Information: Mario Loffredo, [email protected]

11.2. IIT-CNR/Registro.it RDAP Client

  • Responsible Organization: Institute of Informatics and Telematics of National Research Council (IIT-CNR)/Registro.it

  • Location: https://web-rdap.pubtest.nic.it/

  • Description: This is a Javascript web-based RDAP client. RDAP responses are retrieved from RDAP servers by the browser, parsed into an HTML representation, and displayed in a format improving the user experience. Reverse search is allowed to authenticated users.

  • Level of Maturity: This is an "alpha" test implementation.

  • Coverage: This implementation includes all of the features described in this specification.

  • Contact Information: Francesco Donini, [email protected]

12. IANA Considerations

12.1. RDAP Extensions Registry

IANA is requested to register the following value in the "RDAP Extensions" registry:

  • Extension identifier: reverse_search

  • Registry operator: Any

  • Published specification: This document.

  • Contact: IETF <[email protected]>

  • Intended usage: This extension identifier is used for both URI path segments and response extensions related to the reverse search in RDAP.

12.2. RDAP Reverse Search Registries

12.2.1. Creation of the RDAP Reverse Search Registries

IANA is requested to create the "RDAP Reverse Search" and "RDAP Reverse Search Mapping" registries within the group "Registration Data Access Protocol (RDAP)".

These registries follow the Specification Required process as defined in Section 4.5 of [RFC8126].

The designated expert should prevent collisions and confirm that suitable documentation, as described in Section 4.6 of [RFC8126], is available to ensure interoperability.

Creators of either new RDAP reverse searches or new mappings for registered reverse searches SHOULD NOT replicate functionality already available by way of other documents referenced in these registries. Creators MAY register additional reverse search mappings for existing properties, but they SHOULD NOT map a registered reverse search property to a response field with a meaning other than that of the response fields referenced by the mappings already registered for that property. In other words, all the mappings for a reverse search property MUST point to response fields with the same meaning.

12.2.2. Submit Request to IANA

Registration requests can be sent to <[email protected]>.

12.2.3. RDAP Reverse Search Registry

12.2.3.1. Template
"Searchable Resource Type":
The searchable resource type of the reverse search query (Section 2) including the reverse search property. Multiple reverse search properties differing only by this field can be grouped together by listing all the searchable resource types separated by comma (see Section 12.2.3.2).
"Related Resource Type":
The related resource type of the reverse search query (Section 2) including the reverse search property.
"Property":
The name of the reverse search property.
"Description":
A brief human-readable text describing the reverse search property.
"Registrant Name":
The name of the person registering the reverse search property.
"Registrant Contact Information":
An email address, postal address, or some other information to be used to contact the registrant.
"Reference":
Document (e.g. the RFC number) and section reference where the reverse search property is specified.

The combination of "Searchable Resource Type", "Related Resource Type" and "Property" MUST be unique across the registry entries.

12.2.3.2. Initial Content

IANA is requested to register the following entries in the "RDAP Reverse Search" registry.

For all entries, the common values are shown in Table 1 whereas the specific values are shown in Table 2.

Table 1: Common values for all entries in the "RDAP Reverse Search" registry
Registry Property Value
Searchable Resource Type domains, nameservers, entities
Related Resource Type entity
Registrant Name IETF
Registrant Contact Information [email protected]
Reference This document, Section 8
Table 2: Specific values for all entries in the "RDAP Reverse Search" registry
Property Description
fn The server supports the domain/nameserver/entity search based on the full name (a.k.a. formatted name) of an associated entity
handle The server supports the domain/nameserver/entity search based on the handle of an associated entity
email The server supports the domain/nameserver/entity search based on the email address of an associated entity
role The server supports the domain/nameserver/entity search based on the role of an associated entity

12.2.4. RDAP Reverse Search Mapping Registry

12.2.4.1. Template
"Searchable Resource Type":
The same as defined in the "Reverse Search Registry".
"Related Resource Type":
The same as defined in the "Reverse Search Registry".
"Property":
The same as defined in the "Reverse Search Registry".
"Property Path":
The JSONPath of the RDAP property this reverse search property maps to.
"Description":
A brief human-readable text describing this reverse search property mapping.
"Registrant Name":
The name of the person registering this reverse search property mapping.
"Registrant Contact Information":
The same as defined in the "Reverse Search Registry".
"Reference":
Document (e.g. the RFC number) and section reference where this reverse search property mapping is specified.

The combination of "Searchable Resource Type", "Related Resource Type", "Property" and "Property Path" MUST be unique across the registry entries.

12.2.4.2. Initial Content

IANA is requested to register the following entries in the "RDAP Reverse Search Mapping" registry.

For all entries, the common values are the same as defined in the "RDAP Reverse Search" registry (see Table 1) whereas the specific values are shown in Table 3.

Table 3: Specific values for all entries in the "RDAP Reverse Search Mapping" registry
Property Property Path
fn $.entities[*].vcardArray[1][?(@[0]=='fn')][3]
handle $.entities[*].handle
email $.entities[*].vcardArray[1][?(@[0]=='email')][3]
role $.entities[*].roles

13. Privacy Considerations

The search functionality defined in this document may affect the privacy of entities in the registry (and elsewhere) in various ways: see [RFC6973] for a general treatment of privacy in protocol specifications. Registry operators should be aware of the tradeoffs that result from implementation of this functionality.

Many jurisdictions have laws or regulations that restrict the use of "Personal Data", per the definition in [RFC6973]. Given that, registry operators should ascertain whether the regulatory environment in which they operate permits implementation of the functionality defined in this document.

In those cases where this functionality makes use of sensitive information, it MUST only be accessible to authorized users supported by lawful basis.

Since reverse search requests and responses could contain Personally Identifiable Information (PII), reverse search functionality MUST be available over HTTPS only.

Providing reverse search in RDAP carries the following threats as described in [RFC6973]:

Therefore, RDAP providers need to mitigate the risk of those threats by implementing appropriate measures supported by security services (see Section 14).

14. Security Considerations

Security services required to provide controlled access to the operations specified in this document are described in [RFC7481]. A non-exhaustive list of access control paradigms an RDAP provider can implement is presented in Appendix A.

As an additional measure to enforce security by preventing reverse searches to be accessed from unauthorized users, the RDAP providers may consider to physically separate the reverse search endpoints from the other ones by configuring a proxy routing the reverse searches to a dedicated backend server and leveraging further security services offered by other protocol layers such as digital certificates and IP whitelisting.

Finally, the specification of the relationship within the reverse search path allows the RDAP servers to implement different authorization policies on a per-relationship basis.

15. Acknowledgements

The authors would like to acknowledge the following individuals for their contributions to this document: Francesco Donini, Scott Hollenbeck, Francisco Arias, Gustavo Lozano, Eduardo Alvarez, Ulrich Wisser, James Gould and Pawel Kowalik.

Tom Harrison and Jasdip Singh provided relevant feedback and constant support to the implementation of this proposal. Their contributions have been greatly appreciated.

16. References

16.1. Normative References

[I-D.ietf-jsonpath-base]
Gössner, S., Normington, G., and C. Bormann, "JSONPath: Query expressions for JSON", Work in Progress, Internet-Draft, draft-ietf-jsonpath-base-20, , <https://datatracker.ietf.org/doc/html/draft-ietf-jsonpath-base-20>.
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC6350]
Perreault, S., "vCard Format Specification", RFC 6350, DOI 10.17487/RFC6350, , <https://www.rfc-editor.org/info/rfc6350>.
[RFC7095]
Kewisch, P., "jCard: The JSON Format for vCard", RFC 7095, DOI 10.17487/RFC7095, , <https://www.rfc-editor.org/info/rfc7095>.
[RFC7481]
Hollenbeck, S. and N. Kong, "Security Services for the Registration Data Access Protocol (RDAP)", STD 95, RFC 7481, DOI 10.17487/RFC7481, , <https://www.rfc-editor.org/info/rfc7481>.
[RFC7942]
Sheffer, Y. and A. Farrel, "Improving Awareness of Running Code: The Implementation Status Section", BCP 205, RFC 7942, DOI 10.17487/RFC7942, , <https://www.rfc-editor.org/info/rfc7942>.
[RFC8126]
Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, , <https://www.rfc-editor.org/info/rfc8126>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
[RFC9082]
Hollenbeck, S. and A. Newton, "Registration Data Access Protocol (RDAP) Query Format", STD 95, RFC 9082, DOI 10.17487/RFC9082, , <https://www.rfc-editor.org/info/rfc9082>.
[RFC9083]
Hollenbeck, S. and A. Newton, "JSON Responses for the Registration Data Access Protocol (RDAP)", STD 95, RFC 9083, DOI 10.17487/RFC9083, , <https://www.rfc-editor.org/info/rfc9083>.
[RFC9110]
Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, Ed., "HTTP Semantics", STD 97, RFC 9110, DOI 10.17487/RFC9110, , <https://www.rfc-editor.org/info/rfc9110>.

16.2. Informative References

[ICANN-RA]
Internet Corporation For Assigned Names and Numbers, "Registry Agreement", , <https://newgtlds.icann.org/sites/default/files/agreements/agreement-approved-31jul17-en.pdf>.
[ICANN-RDS1]
Internet Corporation For Assigned Names and Numbers, "Final Report from the Expert Working Group on gTLD Directory Services: A Next-Generation Registration Directory Service (RDS)", , <https://www.icann.org/en/system/files/files/final-report-06jun14-en.pdf>.
[ICANN-RDS2]
Internet Corporation For Assigned Names and Numbers, "Final Issue Report on a Next-Generation gTLD RDS to Replace WHOIS", , <http://whois.icann.org/sites/default/files/files/final-issue-report-next-generation-rds-07oct15-en.pdf>.
[OIDCC]
OpenID Foundation, "OpenID Connect Core incorporating errata set 1", , <http://openid.net/specs/openid-connect-core-1_0.html>.
[RFC3912]
Daigle, L., "WHOIS Protocol Specification", RFC 3912, DOI 10.17487/RFC3912, , <https://www.rfc-editor.org/info/rfc3912>.
[RFC5730]
Hollenbeck, S., "Extensible Provisioning Protocol (EPP)", STD 69, RFC 5730, DOI 10.17487/RFC5730, , <https://www.rfc-editor.org/info/rfc5730>.
[RFC6973]
Cooper, A., Tschofenig, H., Aboba, B., Peterson, J., Morris, J., Hansen, M., and R. Smith, "Privacy Considerations for Internet Protocols", RFC 6973, DOI 10.17487/RFC6973, , <https://www.rfc-editor.org/info/rfc6973>.
[RFC8977]
Loffredo, M., Martinelli, M., and S. Hollenbeck, "Registration Data Access Protocol (RDAP) Query Parameters for Result Sorting and Paging", RFC 8977, DOI 10.17487/RFC8977, , <https://www.rfc-editor.org/info/rfc8977>.
[RFC8982]
Loffredo, M. and M. Martinelli, "Registration Data Access Protocol (RDAP) Partial Response", RFC 8982, DOI 10.17487/RFC8982, , <https://www.rfc-editor.org/info/rfc8982>.

Appendix A. Paradigms to Enforce Access Control on Reverse Search in RDAP

Access control can be implemented according to different paradigms introducing increasingly stringent rules. The paradigms reported here in the following leverage the capabilities either built-in or provided as extensions by the OpenID Connect [OIDCC]:

With regard to the privacy threats reported in Section 13, correlation and disclosure can be mitigated by minimizing both the request features and the response data based on user roles (i.e. RBAC). Misuse can be mitigated by checking for the purpose of the request (i.e. PBAC). It can be accomplished according to the following approaches:

The two approaches can be used together:

Appendix B. Change Log

00:
Initial working group version ported from draft-loffredo-regext-rdap-reverse-search-04
01:
Updated "Privacy Considerations" section.
02:
Revised the text.
03:
Refactored the query model.
04:
Keepalive refresh.
05:
Reorganized "Abstract". Corrected "Conventions Used in This Document" section. Added "RDAP Conformance" section. Changed "IANA Considerations" section. Added references to RFC7095 and RFC8174. Other minor edits.
06:
Updated "Privacy Considerations", "Security Considerations" and "Acknowledgements" sections. Added some normative and informative references. Added Appendix A.
07:
Updated normative references.
08:
Changed "Implementation Status" section. Updated informative references.
09:
Extended the query model to represent a reverse search based on any relationship between the RDAP object classes. Changed the path segment "role" into a query parameter.
10:
Updated "Reverse Searches Based on Entity Details" section to consider the use of JSContact format instead of jCard. Added references to JSContact documents.
11:

Updated the document based on Tom Harrison and James Gould feedback:

  • Updated section "RDAP Path Segment Specification":

    • Clarified how servers must evaluate a reverse search including predicates that are for the same property.

    • Specified the error response servers must return when receiving a wrong reverse search request according to their policy.

    • Clarified that searchs for the related-resource-type values other than "entity" may be defined in future documents.

  • Reviewed text in section "Reverse Searches Based on Entity Details" about reverse searches based on custom response extensions.

  • Removed references to JSContact documents in section "Reverse Searches Based on Entity Details". Moved the mapping between jCard properties used in the RDAP response and JSContact counterparts to draft-ietf-regext-rdap-jscontact.

  • Added section "RDAP Response Specification".

  • Changed the text to present reverse search as a single extension with multiple features.

  • Changed the definition of searchable-resource-type and related-resource-type to consider also the resource type extensions.

  • Replaced "reverse" with "reverse_search_0" in the generic reverse search path. Updated Figure 1 accordingly.

  • Removed the phrase "but with a special focus on its privacy implications" from both the "Abstract" and the "Introduction". Moved the mapping between jCard properties used in the RDAP response and JSContact counterparts to draft-ietf-regext-rdap-jscontact.

  • Reviewed the text of "Privacy Considerations" section.

  • Text cleaning.

12:
Replaced "reverse_search_0" with "reverse_search" as both URI path segment, extension identifier and rdapConformance tag to match the working group consensus.
13:
Done some minor text changes.
14:
Revised text of first sentence and added references to RFC8977 and RFC8982 in the "Implementation Considerations" section.
15:
Moved RFC6973 from Normative References to Informative References. Remnoved informative reference to draft-ietf-regext-rdap-openid. Rephrased text in Appendix A accordingly.
16:
Moved OIDC from Normative References to Informative References. Added the "Reverse Search Properties Discovery" section. Added "RDAP JSON Values Registry" as a subsection of the "IANA Considerations" section. Rephrased the "Reverse Searches Based on Entity Details" section to refer to the "Reverse Search Properties Discovery" section. Updated the "Acknowledgements" section. Minor text edits.
17:
Revised the "Reverse Search Properties Discovery" section. Replaced "RDAP JSON Values Registry" section with the "RDAP Reverse Search Properties Registry" section.
18:
Changed "Expert Review" with "Specification Required" in the "Creation of the RDAP Reverse Search Properties Registry" section. Renamed the "RDAP Reverse Search Properties Registry" into "RDAP Reverse Search Registry". Aligned the RDAP Reverse Search Registry template with the initial content. Introduced the "reverse_search_properties_mapping" response extension. Added the "RDAP Reverse Search Mapping Registry". Reorganized the document to separate the implementation of a generic reverse search from that based on domain-entity relationship.
19:
Added the "Reverse Search Query Processing" section. Changed the definition of search-condition in Section 2. Moved the "Reverse Search Response Specification" section. Corrected Figure 3.
20:
  • Changed document title.
  • Changed "Servers MUST NOT provide or implement unregistered reverse searches or unregistered reverse search mappings." to "Servers MUST NOT provide or implement reverse searches or reverse search mappings that are not registered with IANA." in Section 3.
  • Changed "...that the RDAP response property "roles" must contain at least the specified role" to "...that the RDAP response property "roles" MUST contain at least the specified role" in Section 8.
  • Changed the value of the "Intended usage" property of the "RDAP Extensions Registry" entry in Section 12.1.
  • Changed "..., reverse search functionality SHOULD be available over HTTPS only." to "..., reverse search functionality MUST be available over HTTPS only." in Section 13.
21:
  • Added a sentence about servers signaling the unsupported reverse searches to Section 7.
  • Replaced "$.." with "$." in JSONPath expressions.
  • Clarified that the registry group the new registries must be added to is "Registration Data Access Protocol (RDAP)".
  • Removed unused normative reference to RFC7480.
22:
  • Expanded EPP acronym in Section 1.
  • Moved RFC3912 and RFC5730 from normative to informative references.
23:
  • Replaced IESG with IETF as the Registrant Name for each entry in the IANA registries.
  • Rearranged the layout of the initial content for the IANA registries.
  • Added titles to figures.
  • Repalced "RDAP providers are REQUIRED to" with "RDAP providers need to" in Section 14.
  • Text cleaning.
24:
  • Added text to Section 12.2.1 to make the term "collisions" clear enough for future DEs.
  • Added titles to tables.
25:
  • Added text to Section 1 to reference the implications of this specification on efficiency, security and compliance with privacy regulations.
  • Changed text in Privacy Considerations to clarify that in those cases where sensitive information are used, this feature MUST be accessble to authorized users only.
  • Added text to Section 14 to describe additional measures to enforce the security.
  • Added text to Appendix A to clarify how the proposed access control paradigms can contribute to mitigate the threats listed in Section 13.
  • Moved the reference to RFC3912.
  • Moved reference to draft-ietf-jsonpath-based to Normative References.
  • Text cleaning.

Authors' Addresses

Mario Loffredo
IIT-CNR/Registro.it
Via Moruzzi,1
56124 Pisa
Italy
Maurizio Martinelli
IIT-CNR/Registro.it
Via Moruzzi,1
56124 Pisa
Italy