draft-ietf-regext-rdap-reverse-search-10.txt		draft-ietf-regext-rdap-reverse-search-11.txt
	Registration Protocols Extensions M. Loffredo		Registration Protocols Extensions M. Loffredo
	Internet-Draft M. Martinelli		Internet-Draft M. Martinelli
	Intended status: Standards Track IIT-CNR/Registro.it		Intended status: Standards Track IIT-CNR/Registro.it
	Expires: 10 October 2022 8 April 2022		Expires: 3 November 2022 2 May 2022
	Registration Data Access Protocol (RDAP) Reverse search capabilities		Registration Data Access Protocol (RDAP) Reverse search capabilities
	draft-ietf-regext-rdap-reverse-search-10		draft-ietf-regext-rdap-reverse-search-11
	Abstract		Abstract
	The Registration Data Access Protocol (RDAP) does not include query		The Registration Data Access Protocol (RDAP) does not include query
	capabilities to find the list of domains related to a set of entities		capabilities for finding the list of domains related to a set of
	matching a given search pattern. In the RDAP context, an entity can		entities matching a given search pattern. In the RDAP context, an
	be associated with any defined object class. Moreover, other		entity can be associated with any defined object class. Moreover,
	relationships between object classes exist and might be used for		other relationships between object classes exist and might be used
	providing a reverse search capability. Therefore, a reverse search		for providing a reverse search capability. Therefore, a reverse
	can be applied to other use cases than the classic domain-entity		search can be applied to other use cases than the classic domain-
	scenario. This document describes RDAP query extensions that allow		entity scenario. This document describes an RDAP extension that
	servers to provide a reverse search feature based on the relationship		allow servers to provide a reverse search feature based on the
	defined in RDAP between an object class for search and any related		relationship defined in RDAP between an object class for search and
	object class. The reverse search based on the domain-entity		any related object class. The reverse search based on the domain-
	relationship is treated as a particular case but with a special focus		entity relationship is treated as a particular case.
	on its privacy implications.
	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 10 October 2022.		This Internet-Draft will expire on 3 November 2022.
	Copyright Notice		Copyright Notice
	Copyright (c) 2022 IETF Trust and the persons identified as the		Copyright (c) 2022 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 (https://trustee.ietf.org/		Provisions Relating to IETF Documents (https://trustee.ietf.org/
	license-info) in effect on the date of publication of this document.		license-info) in effect on the date of publication of this document.
	Please review these documents carefully, as they describe your rights		Please review these documents carefully, as they describe your rights
	and restrictions with respect to this document. Code Components		and restrictions with respect to this document. Code Components
	extracted from this document must include Revised BSD License text as		extracted from this document must include Revised BSD License text as
	described in Section 4.e of the Trust Legal Provisions and are		described in Section 4.e of the Trust Legal Provisions and are
	provided without warranty as described in the Revised BSD License.		provided without warranty as described in the Revised BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	1.1. Conventions Used in This Document . . . . . . . . . . . . 4		1.1. Conventions Used in This Document . . . . . . . . . . . . 4
	2. RDAP Path Segment Specification . . . . . . . . . . . . . . . 4		2. RDAP Path Segment Specification . . . . . . . . . . . . . . . 4
	2.1. Reverse Searches Based on Entity Details . . . . . . . . 4		3. RDAP Response Specification . . . . . . . . . . . . . . . . . 5
	3. RDAP Conformance . . . . . . . . . . . . . . . . . . . . . . 6		4. Reverse Searches Based on Entity Details . . . . . . . . . . 5
	4. Implementation Considerations . . . . . . . . . . . . . . . . 6		5. RDAP Conformance . . . . . . . . . . . . . . . . . . . . . . 6
	5. Implementation Status . . . . . . . . . . . . . . . . . . . . 6		6. Implementation Considerations . . . . . . . . . . . . . . . . 6
	5.1. IIT-CNR/Registro.it RDAP Server . . . . . . . . . . . . . 7		7. Implementation Status . . . . . . . . . . . . . . . . . . . . 7
	5.2. IIT-CNR/Registro.it RDAP Client . . . . . . . . . . . . . 7		7.1. IIT-CNR/Registro.it RDAP Server . . . . . . . . . . . . . 7
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7		7.2. IIT-CNR/Registro.it RDAP Client . . . . . . . . . . . . . 7
	7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 8		8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 8		9. Privacy Considerations . . . . . . . . . . . . . . . . . . . 8
	9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8		10. Security Considerations . . . . . . . . . . . . . . . . . . . 9
	10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9		11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
	10.1. Normative References . . . . . . . . . . . . . . . . . . 9		12. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
	10.2. Informative References . . . . . . . . . . . . . . . . . 10		12.1. Normative References . . . . . . . . . . . . . . . . . . 9
			12.2. Informative References . . . . . . . . . . . . . . . . . 10
	Appendix A. Paradigms to Enforce Access Control on Reverse Search		Appendix A. Paradigms to Enforce Access Control on Reverse Search
	in RDAP . . . . . . . . . . . . . . . . . . . . . . . . . 11		in RDAP . . . . . . . . . . . . . . . . . . . . . . . . . 11
	Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 12		Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 12
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
	1. Introduction		1. Introduction
	Reverse Whois is a service provided by many web applications that		Reverse Whois is a service provided by many web applications that
	allow users to find domain names owned by an individual or a company		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		starting from the owner's details, such as name and email. Even if
	it has been considered useful for some legal purposes (e.g.		it has been considered useful for some legal purposes (e.g.
	uncovering trademark infringements, detecting cybercrimes), its		uncovering trademark infringements, detecting cybercrimes), its
	availability as a standardized Whois capability has been objected to		availability as a standardized Whois capability has been objected to
	for two main reasons, which now don't seem to conflict with an RDAP		for two main reasons, which now don't seem to conflict with an RDAP
	implementation.		implementation.
	The first objection has been caused by the potential risks of privacy		The first objection concerns the potential risks of privacy
	violation. However, TLDs community is considering a new generation		violation. However, the domain name community is considering a new
	of Registration Directory Services [ICANN-RDS1] [ICANN-RDS2]		generation of Registration Directory Services [ICANN-RDS1]
	[ICANN-RA], which provide access to sensitive data under some		[ICANN-RDS2] [ICANN-RA], which provide access to sensitive data under
	permissible purposes and according to adequate policies to enforce		some permissible purposes and in accordance with appropriate policies
	the requestor accreditation, authentication, authorization, and terms		for requestor accreditation, authentication and authorization.
	and conditions of data use. It is well known that such security		RDAP's reliance on HTTP means that it can make use of common HTTP-
	policies are not implemented in Whois [RFC3912], while they are in		based approaches to authentication and authorization, making it more
	RDAP [RFC7481]. Therefore, RDAP permits a reverse search		useful than Whois [RFC3912] in the context of such directory
	implementation complying with privacy protection principles.		services. Since RDAP consequently permits a reverse search
			implementation complying with privacy protection principles, this
			objection is not well-founded.
	The other objection to the implementation of a reverse search		The other objection to the implementation of a reverse search
	capability has been connected with its impact on server processing.		capability has been connected with its impact on server processing.
	Since RDAP supports search queries, the impact of both standard and		However, the core RDAP specifications already define search queries,
	reverse searches is equivalent and can be mitigated by servers		with similar processing requirements, so the distinction on which
	adopting ad hoc strategies. Furthermore, the reverse search is		this objection is based is not clear.
	almost always performed by specifying an entity role (e.g.
	registrant, technical contact) and this can contribute to restricting
	the result set.
	Reverse searches, such as finding the list of domain names associated		Reverse searches, such as finding the list of domain names associated
	with contacts or nameservers may be useful to registrars as well.		with contacts or nameservers, may be useful to registrars as well.
	Usually, registries adopt out-of-band solutions to provide results to		Usually, registries adopt out-of-band solutions to provide results to
	registrars asking for reverse searches on their domains. Possible		registrars asking for reverse searches on their domains. Possible
	reasons for such requests are:		reasons for such requests are:
	* the loss of synchronization between the registrar database and the		* the loss of synchronization between the registrar database and the
	registry database;		registry database;
	* the need for such data to perform massive EPP [RFC5730] updates		* the need for such data to perform bulk EPP [RFC5730] updates (e.g.
	(e.g. changing the contacts of a set of domains, etc.).		changing the contacts of a set of domains, etc.).
	Currently, RDAP does not provide any means for a client to search for		Currently, RDAP does not provide any means for a client to search for
	the collection of domains associated with an entity [RFC9082]. A		the collection of domains associated with an entity [RFC9082]. A
	query (lookup or search) on domains can return the array of entities		query (lookup or search) on domains can return the array of entities
	related to a domain with different roles (registrant, registrar,		related to a domain with different roles (registrant, registrar,
	administrative, technical, reseller, etc.), but the reverse operation		administrative, technical, reseller, etc.), but the reverse operation
	is not allowed. Only reverse searches to find the collection of		is not allowed. Only reverse searches to find the collection of
	domains related to a nameserver (ldhName or ip) can be requested.		domains related to a nameserver (ldhName or ip) can be requested.
	Since an entity can be in relationship with any RDAP object		Since an entity can be in relationship with any RDAP object
	[RFC9083], the availability of a reverse search as largely intended		[RFC9083], the availability of a reverse search as largely intended
	can be common to all the object classes allowed for search. Through		can be common to all the object classes allowed for search. Through
	a further step of generalization, the meaning of reverse search in		a further step of generalization, the meaning of reverse search in
	the RDAP context can be extended to include any query for retrieving		the RDAP context can be extended to include any query for retrieving
	all the objects in relationship with another matching a given search		all the objects in relationship with another matching a given search
	pattern.		pattern.
	The protocol described in this specification aims to extend the RDAP		The protocol described in this specification aims to extend the RDAP
	query capabilities to enable the reverse search based on the		query capabilities to enable reverse search based on the
	relationships defined in RDAP between an object class for search and		relationships defined in RDAP between an object class for search and
	any related object class. The reverse search based on the domain-		a related object class. The reverse search based on the domain-
	entity relationship is treated as a particular case of such a generic		entity relationship is treated as a particular case of such a generic
	query model but with a special focus on its privacy implications.		query model.
	The extension is implemented by adding new path segments (i.e. search
	paths) and using a RESTful web service [REST]. The service is
	implemented using the Hypertext Transfer Protocol (HTTP) [RFC7230]
	and the conventions described in [RFC7480].
	1.1. Conventions Used in This Document		1.1. Conventions Used in This Document
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in BCP		"OPTIONAL" in this document are to be interpreted as described in BCP
	14 [RFC2119] [RFC8174] when, and only when, they appear in all		14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	2. RDAP Path Segment Specification		2. RDAP Path Segment Specification
	The new search paths are OPTIONAL extensions of those defined in		A generic reverse search path is described by the syntax:
	[RFC9082]. A generic reverse search path is described by the syntax:
	{searchable-resource-type}/reverse/{related-resource-type}?<search-		{searchable-resource-type}/reverse_search_0/{related-resource-
	condition>		type}?<search-condition>
	The path segments are defined as in the following:		The path segments are defined as in the following:
	* searchable-resource-type: it MUST be one of resource types for		* searchable-resource-type: it MUST be one of the resource types for
	search defined in Section 3.2 of [RFC9082], i.e. "domains",		search defined in Section 3.2 of [RFC9082] (i.e. "domains",
	"nameservers" and "entities";		"nameservers" and "entities") or a resource type extension;
	* related-resource-type: it MUST be one of the resource types for		* related-resource-type: it MUST be one of the resource types for
	lookup defined in Section 3.1 of [RFC9082], i.e. "domain",		lookup defined in Section 3.1 of [RFC9082] (i.e. "domain",
	"nameserver", "entity", "ip" and "autnum";		"nameserver", "entity", "ip" and "autnum") or a resource type
			extension;
	* search-condition: a sequence of "property=search pattern"		* search-condition: a sequence of "property=search pattern"
	predicates separated by the ampersand character ('&', US-ASCII		predicates separated by the ampersand character ('&', US-ASCII
	value 0x0026). Each "property" represents a JSON object property		value 0x0026). Each "property" represents a JSON object property
	of the RDAP object class corresponding to "related-resource-type".		of the RDAP object class corresponding to "related-resource-type".
	All the predicates are joined by the AND logical operator. Based		Objects are only included in the search results if they satisfy
	on their policy, servers MAY restrict the usage of predicates to		all included predicates. This includes predicates that are for
	make a valid search condition.		the same property: it is necessary in such a case for the related
			object to match against each of those predicates. Based on their
			policy, servers MAY restrict the usage of predicates to make a
			valid search condition, by returning a 400 (Bad Request) response
			when a problematic request is received.
			While related-resource-type is defined as having one of a number of
			different values, the only searches defined in this document are for
			a related-resource-type of "entity". Searches for the other resource
			types specified in [RFC9082] and resource type extensions may be
			defined by future documents.
	Partial string matching in search patterns is allowed as defined in		Partial string matching in search patterns is allowed as defined in
	section 4.1 of [RFC9082].		section 4.1 of [RFC9082].
	2.1. Reverse Searches Based on Entity Details		3. RDAP 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.
			4. Reverse Searches Based on Entity Details
	Since in RDAP, an entity can be associated with any other object		Since in RDAP, an entity can be associated with any other object
	class, the most common kind of reverse searches are based on the		class, the most common kind of reverse search is one based on an
	entity details. Such reverse searches arise from the above query		entity's details. Such reverse searches arise from the query model
	model by setting the related resource type to "entity".		by setting the related resource type to "entity".
	By selecting a specific searchable resource type, the resulting		By selecting a specific searchable resource type, the resulting
	reverse search aims at retrieving all the objects (e.g. all the		reverse search aims at retrieving all the objects (e.g. all the
	domains) that are related to any entity object matching the search		domains) that are related to any entity object matching the search
	condition.		conditions.
	This section defines the following reverse search properties to be		This section defines the following reverse search properties servers
	used regardless of the searchable resource type being selected:		SHOULD support regardless of the searchable resource type being
			selected:
	Reverse search property: role		Reverse search property: role
	RDAP property: $..entities[*].roles		RDAP property: $..entities[*].roles
	Reference: Section 10.2.4 of [RFC9083]		Reference: Section 10.2.4 of [RFC9083]
	Reverse search property: handle		Reverse search property: handle
	RDAP property: $..entities[*].handle		RDAP property: $..entities[*].handle
	Reference: Section 5.1 of [RFC9083]		Reference: Section 5.1 of [RFC9083]
	Reverse search property: fn		Reverse search property: fn
	Using jCard:
	RDAP property: $..entities[*].vcardArray[1][?(@[0]=='fn')][3]		RDAP property: $..entities[*].vcardArray[1][?(@[0]=='fn')][3]
	Reference: Section 6.2.1 of [RFC6350]		Reference: Section 6.2.1 of [RFC6350]
	Using JSContact:
	RDAP property: $..entities[*].jscard.fullName
	Reference: Section 2.2.2 of [I-D.ietf-calext-jscontact]
	Reverse search property: email		Reverse search property: email
	Using jCard:
	RDAP property: $..entities[*].vcardArray[1][?(@[0]=='email')][3]		RDAP property: $..entities[*].vcardArray[1][?(@[0]=='email')][3]
	Reference: Section 6.4.2 of [RFC6350]		Reference: Section 6.4.2 of [RFC6350]
	Using JSContact:
	RDAP property: $..entities[*].jscard.emails.[*].email
	Reference: Section 2.3.1 of [I-D.ietf-calext-jscontact]
	Regarding the above definitions, it must be noted that:		The mapping between the reverse search property and the corresponding
			RDAP response property is done through the use of a JSONPath
			expression [I-D.ietf-jsonpath-base].
	* the mapping between the reverse search property and the		The presence of a predicate on the reverse search property "role"
	corresponding RDAP response property is done through the use of a		means that the RDAP response property "roles" must contain at least
	JSONPath expression [I-D.ietf-jsonpath-base];		the specified role.
	* 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, being jCard the JSON format for vCard, the corresponding
	reference is to the vCard specification [RFC6350]. Such
	properties are also shown according to the JSContact format
	[I-D.ietf-calext-jscontact] to address the case when it is used
	instead of jCard as described in [I-D.ietf-regext-rdap-jscontact].
	Servers MAY implement other properties than those defined in this		The last two properties are related to jCard elements [RFC7095], but
	section.		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		Examples of reverse search paths based on the domain-entity
	relationship are presented below:		relationship are presented in Figure 1.
	/domains/reverse/entity?handle=CID-40*&role=technical		/domains/reverse_search_0/entity?handle=CID-40*&role=technical
	/domains/reverse/entity?fn=Bobby*&role=registrant		/domains/reverse_search_0/entity?fn=Bobby*&role=registrant
	/domains/reverse/entity?handle=RegistrarX&role=registrar		/domains/reverse_search_0/entity?handle=RegistrarX&role=registrar
	Figure 1		Figure 1
	3. RDAP Conformance		Documents that deprecate or restructure RDAP responses such that one
			or more of the properties listed above becomes invalid 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 way of some new RDAP property (in the case of
			restructuring).
			A server that includes additional fields in its objects in accordance
			with the extensibility provisions of section 6 of [RFC7480] MAY
			support the use of those fields in search conditions, in the same way
			as for the search conditions defined in this section. Support for
			such fields in the reverse search context MUST be documented in the
			extension specification.
			5. RDAP Conformance
	Servers complying with this specification MUST include the value		Servers complying with this specification MUST include the value
	"reverse_search_0" in the rdapConformance property of the help		"reverse_search_0" in the rdapConformance property of the help
	response [RFC9083]. The information needed to register this value in		response [RFC9083]. The information needed to register this value in
	the "RDAP Extensions" registry is described in Section 6.		the "RDAP Extensions" registry is described in Section 8.
	4. Implementation Considerations		6. Implementation Considerations
	The implementation of the proposed extension is technically feasible.
	To limit the impact of processing the search predicates, servers are		To limit the impact of processing the search predicates, servers are
	RECOMMENDED to mandate the use of at least one property among those		RECOMMENDED to make use of indexes and similar functionality in their
	mapped to indexed fields of the registry database. Other properties,		underlying data store. In addition, risks with respect to
	such as "role", MAY be allowed to further restrict the set of		performance degradation or result set generation can be mitigated by
	possible results. In addition, the risks to degrade the performance		adopting practices used for standard searches, e.g. restricting the
	or to generate huge result sets can be mitigated by adopting the same		search functionality, limiting the rate of search requests according
	policies valid for handling searches (e.g. restricting the search		to the user's authorization, truncating and paging the results, and
	functionality, limiting the rate of search requests according to the		returning partial responses.
	user profile, truncating and paging the results, returning partial
	responses).
	5. Implementation Status		7. Implementation Status
	NOTE: Please remove this section and the reference to RFC 7942 prior		NOTE: Please remove this section and the reference to RFC 7942 prior
	to publication as an RFC.		to publication as an RFC.
	This section records the status of known implementations of the		This section records the status of known implementations of the
	protocol defined by this specification at the time of posting of this		protocol defined by this specification at the time of posting of this
	Internet-Draft, and is based on a proposal described in [RFC7942].		Internet-Draft, and is based on a proposal described in [RFC7942].
	The description of implementations in this section is intended to		The description of implementations in this section is intended to
	assist the IETF in its decision processes in progressing drafts to		assist the IETF in its decision processes in progressing drafts to
	RFCs. Please note that the listing of any individual implementation		RFCs. Please note that the listing of any individual implementation
	skipping to change at page 7, line 16 ¶		skipping to change at page 7, line 30 ¶
	features. Readers are advised to note that other implementations may		features. Readers are advised to note that other implementations may
	exist.		exist.
	According to RFC 7942, "this will allow reviewers and working groups		According to RFC 7942, "this will allow reviewers and working groups
	to assign due consideration to documents that have the benefit of		to assign due consideration to documents that have the benefit of
	running code, which may serve as evidence of valuable experimentation		running code, which may serve as evidence of valuable experimentation
	and feedback that have made the implemented protocols more mature.		and feedback that have made the implemented protocols more mature.
	It is up to the individual working groups to use this information as		It is up to the individual working groups to use this information as
	they see fit".		they see fit".
	5.1. IIT-CNR/Registro.it RDAP Server		7.1. IIT-CNR/Registro.it RDAP Server
	* Responsible Organization: Institute of Informatics and Telematics		* Responsible Organization: Institute of Informatics and Telematics
	of National Research Council (IIT-CNR)/Registro.it		of National Research Council (IIT-CNR)/Registro.it
	* Location: https://rdap.pubtest.nic.it/		* Location: https://rdap.pubtest.nic.it/
	* Description: This implementation includes support for RDAP queries		* Description: This implementation includes support for RDAP queries
	using data from the public test environment of .it ccTLD. Reverse		using data from the public test environment of .it ccTLD. Reverse
	search is allowed to authenticated users. Registrar users are		search is allowed to authenticated users. Registrar users are
	allowed to perform reverse searches on their own domains and		allowed to perform reverse searches on their own domains and
	contacts. This is achieved by adding an implicit condition to the		contacts. This is achieved by adding an implicit predicate to the
	search pattern.		search condition.
	* Level of Maturity: This is an "alpha" test implementation.		* Level of Maturity: This is an "alpha" test implementation.
	* Coverage: This implementation includes all of the features		* Coverage: This implementation includes all of the features
	described in this specification.		described in this specification.
	* Contact Information: Mario Loffredo, mario.loffredo@iit.cnr.it		* Contact Information: Mario Loffredo, mario.loffredo@iit.cnr.it
	5.2. IIT-CNR/Registro.it RDAP Client		7.2. IIT-CNR/Registro.it RDAP Client
	* Responsible Organization: Institute of Informatics and Telematics		* Responsible Organization: Institute of Informatics and Telematics
	of National Research Council (IIT-CNR)/Registro.it		of National Research Council (IIT-CNR)/Registro.it
	* Location: https://web-rdap.pubtest.nic.it/		* Location: https://web-rdap.pubtest.nic.it/
	* Description: This is a Javascript web-based RDAP client. RDAP		* Description: This is a Javascript web-based RDAP client. RDAP
	responses are retrieved from RDAP servers by the browser, parsed		responses are retrieved from RDAP servers by the browser, parsed
	into an HTML representation, and displayed in a format improving		into an HTML representation, and displayed in a format improving
	the user experience. Reverse search is allowed to authenticated		the user experience. Reverse search is allowed to authenticated
	users.		users.
	* Level of Maturity: This is an "alpha" test implementation.		* Level of Maturity: This is an "alpha" test implementation.
	* Coverage: This implementation includes all of the features		* Coverage: This implementation includes all of the features
	described in this specification.		described in this specification.
	* Contact Information: Francesco Donini, francesco.donini@iit.cnr.it		* Contact Information: Francesco Donini, francesco.donini@iit.cnr.it
	6. IANA Considerations		8. IANA Considerations
	IANA is requested to register the following value in the RDAP		IANA is requested to register the following value in the RDAP
	Extensions Registry:		Extensions Registry:
	* Extension identifier: reverse_search_0		* Extension identifier: reverse_search_0
	* Registry operator: Any		* Registry operator: Any
	* Published specification: This document.		* Published specification: This document.
	* Contact: IETF <iesg@ietf.org>		* Contact: IETF <iesg@ietf.org>
	* Intended usage: This extension describes reverse search query		* Intended usage: This extension describes reverse search query
	patterns for RDAP.		patterns for RDAP.
	7. Privacy Considerations		9. Privacy Considerations
	The use of the capability described in this document whenever a		The search functionality defined in this document may affect the
	contact detail is taken MUST be compliant with the rules about		privacy of entities in the registry (and elsewhere) in various ways:
	privacy protection each RDAP provider is subject to. Sensitive		see [RFC6973] for a general treatment of privacy in protocol
	registration data MUST be protected and accessible for permissible		specifications. Registry operators should be aware of the tradeoffs
	purposes only. This feature SHOULD be only accessible to authorized		that result from implementation of this functionality.
	users and only for a specified use case.
	Since the request for this feature could contain Personal		Many jurisdictions have laws or regulations that restrict the use of
	Identifiable Information, it SHOULD only be accessible to authorized		"Personal Data", per the definition in [RFC6973]. Given that,
	users and available over HTTPS.		registry operators should ascertain whether the regulatory
			environment in which they operate permits implementation of the
			functionality defined in this document.
			In general, given the sensitivity of this functionality,it SHOULD be
			accessible to authorized users only, and for specific use cases only.
			Since reverse search requests and responses could contain Personally
			Identifiable Information (PII), reverse search functionality SHOULD
			be available over HTTPS only.
	Providing reverse search in RDAP carries the following threats as		Providing reverse search in RDAP carries the following threats as
	described in [RFC6973]:		described in [RFC6973]:
	* Correlation		* Correlation
	* Disclosure		* Disclosure
	* Misuse of information		* Misuse of information
	Therefore, RDAP providers are REQUIRED to mitigate the risk of those		Therefore, RDAP providers are REQUIRED to mitigate the risk of those
	threats by implementing appropriate measures supported by security		threats by implementing appropriate measures supported by security
	services (see Section 8).		services (see Section 10).
	8. Security Considerations		10. Security Considerations
	Security services required to provide controlled access to the		Security services required to provide controlled access to the
	operations specified in this document are described in [RFC7481]. A		operations specified in this document are described in [RFC7481]. A
	non-exhaustive list of access control paradigms an RDAP provider can		non-exhaustive list of access control paradigms an RDAP provider can
	implement is presented in Appendix A.		implement is presented in Appendix A.
	The specification of the relationship within the reverse search path		The specification of the relationship within the reverse search path
	allows the RDAP servers to implement different authorization policies		allows the RDAP servers to implement different authorization policies
	on a per-relationship basis.		on a per-relationship basis.
	9. Acknowledgements		11. Acknowledgements
	The authors would like to acknowledge the following individuals for		The authors would like to acknowledge the following individuals for
	their contributions to this document: Francesco Donini, Scott		their contributions to this document: Francesco Donini, Scott
	Hollenbeck, Francisco Arias, Gustavo Lozano, Eduardo Alvarez and		Hollenbeck, Francisco Arias, Gustavo Lozano, Eduardo Alvarez, Ulrich
	Ulrich Wisser.		Wisser and James Gould.
	Tom Harrison and Jasdip Singh provided relevant feedback and constant		Tom Harrison and Jasdip Singh provided relevant feedback and constant
	support to the implementation of this proposal. Their contributions		support to the implementation of this proposal. Their contributions
	are greatly appreciated.		have been greatly appreciated.
	10. References		12. References
	10.1. Normative References		12.1. Normative References
	[OIDCC] OpenID Foundation, "OpenID Connect Core incorporating		[OIDCC] OpenID Foundation, "OpenID Connect Core incorporating
	errata set 1", November 2014,		errata set 1", November 2014,
	<http://openid.net/specs/openid-connect-core-1_0.html>.		<http://openid.net/specs/openid-connect-core-1_0.html>.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	skipping to change at page 9, line 44 ¶		skipping to change at page 10, line 19 ¶
	[RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,		[RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
	Morris, J., Hansen, M., and R. Smith, "Privacy		Morris, J., Hansen, M., and R. Smith, "Privacy
	Considerations for Internet Protocols", RFC 6973,		Considerations for Internet Protocols", RFC 6973,
	DOI 10.17487/RFC6973, July 2013,		DOI 10.17487/RFC6973, July 2013,
	<https://www.rfc-editor.org/info/rfc6973>.		<https://www.rfc-editor.org/info/rfc6973>.
	[RFC7095] Kewisch, P., "jCard: The JSON Format for vCard", RFC 7095,		[RFC7095] Kewisch, P., "jCard: The JSON Format for vCard", RFC 7095,
	DOI 10.17487/RFC7095, January 2014,		DOI 10.17487/RFC7095, January 2014,
	<https://www.rfc-editor.org/info/rfc7095>.		<https://www.rfc-editor.org/info/rfc7095>.
	[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
	Protocol (HTTP/1.1): Message Syntax and Routing",
	RFC 7230, DOI 10.17487/RFC7230, June 2014,
	<https://www.rfc-editor.org/info/rfc7230>.
	[RFC7480] Newton, A., Ellacott, B., and N. Kong, "HTTP Usage in the		[RFC7480] Newton, A., Ellacott, B., and N. Kong, "HTTP Usage in the
	Registration Data Access Protocol (RDAP)", STD 95,		Registration Data Access Protocol (RDAP)", STD 95,
	RFC 7480, DOI 10.17487/RFC7480, March 2015,		RFC 7480, DOI 10.17487/RFC7480, March 2015,
	<https://www.rfc-editor.org/info/rfc7480>.		<https://www.rfc-editor.org/info/rfc7480>.
	[RFC7481] Hollenbeck, S. and N. Kong, "Security Services for the		[RFC7481] Hollenbeck, S. and N. Kong, "Security Services for the
	Registration Data Access Protocol (RDAP)", STD 95,		Registration Data Access Protocol (RDAP)", STD 95,
	RFC 7481, DOI 10.17487/RFC7481, March 2015,		RFC 7481, DOI 10.17487/RFC7481, March 2015,
	<https://www.rfc-editor.org/info/rfc7481>.		<https://www.rfc-editor.org/info/rfc7481>.
	skipping to change at page 10, line 29 ¶		skipping to change at page 10, line 48 ¶
	[RFC9082] Hollenbeck, S. and A. Newton, "Registration Data Access		[RFC9082] Hollenbeck, S. and A. Newton, "Registration Data Access
	Protocol (RDAP) Query Format", STD 95, RFC 9082,		Protocol (RDAP) Query Format", STD 95, RFC 9082,
	DOI 10.17487/RFC9082, June 2021,		DOI 10.17487/RFC9082, June 2021,
	<https://www.rfc-editor.org/info/rfc9082>.		<https://www.rfc-editor.org/info/rfc9082>.
	[RFC9083] Hollenbeck, S. and A. Newton, "JSON Responses for the		[RFC9083] Hollenbeck, S. and A. Newton, "JSON Responses for the
	Registration Data Access Protocol (RDAP)", STD 95,		Registration Data Access Protocol (RDAP)", STD 95,
	RFC 9083, DOI 10.17487/RFC9083, June 2021,		RFC 9083, DOI 10.17487/RFC9083, June 2021,
	<https://www.rfc-editor.org/info/rfc9083>.		<https://www.rfc-editor.org/info/rfc9083>.
	10.2. Informative References		12.2. Informative References
	[I-D.ietf-calext-jscontact]
	Stepanek, R. and M. Loffredo, "JSContact: A JSON
	representation of contact data", Work in Progress,
	Internet-Draft, draft-ietf-calext-jscontact-00, 17 January
	2020, <https://www.ietf.org/archive/id/draft-ietf-calext-
	jscontact-00.txt>.
	[I-D.ietf-jsonpath-base]		[I-D.ietf-jsonpath-base]
	Gössner, S., Normington, G., and C. Bormann, "JSONPath:		Gössner, S., Normington, G., and C. Bormann, "JSONPath:
	Query expressions for JSON", Work in Progress, Internet-		Query expressions for JSON", Work in Progress, Internet-
	Draft, draft-ietf-jsonpath-base-03, 16 January 2022,		Draft, draft-ietf-jsonpath-base-03, 16 January 2022,
	<https://www.ietf.org/archive/id/draft-ietf-jsonpath-base-		<https://www.ietf.org/archive/id/draft-ietf-jsonpath-base-
	03.txt>.		03.txt>.
	[I-D.ietf-regext-rdap-jscontact]
	Loffredo, M. and G. Brown, "Using JSContact in
	Registration Data Access Protocol (RDAP) JSON Responses",
	Work in Progress, Internet-Draft, draft-ietf-regext-rdap-
	jscontact-09, 7 March 2022,
	<https://www.ietf.org/archive/id/draft-ietf-regext-rdap-
	jscontact-09.txt>.
	[I-D.ietf-regext-rdap-openid]		[I-D.ietf-regext-rdap-openid]
	Hollenbeck, S., "Federated Authentication for the		Hollenbeck, S., "Federated Authentication for the
	Registration Data Access Protocol (RDAP) using OpenID		Registration Data Access Protocol (RDAP) using OpenID
	Connect", Work in Progress, Internet-Draft, draft-ietf-		Connect", Work in Progress, Internet-Draft, draft-ietf-
	regext-rdap-openid-08, 8 November 2021,		regext-rdap-openid-08, 8 November 2021,
	<https://www.ietf.org/archive/id/draft-ietf-regext-rdap-		<https://www.ietf.org/archive/id/draft-ietf-regext-rdap-
	openid-08.txt>.		openid-08.txt>.
	[ICANN-RA] Internet Corporation For Assigned Names and Numbers,		[ICANN-RA] Internet Corporation For Assigned Names and Numbers,
	"Registry Agreement", July 2017,		"Registry Agreement", July 2017,
	skipping to change at page 11, line 33 ¶		skipping to change at page 11, line 36 ¶
	<https://www.icann.org/en/system/files/files/final-report-		<https://www.icann.org/en/system/files/files/final-report-
	06jun14-en.pdf>.		06jun14-en.pdf>.
	[ICANN-RDS2]		[ICANN-RDS2]
	Internet Corporation For Assigned Names and Numbers,		Internet Corporation For Assigned Names and Numbers,
	"Final Issue Report on a Next-Generation gTLD RDS to		"Final Issue Report on a Next-Generation gTLD RDS to
	Replace WHOIS", October 2015,		Replace WHOIS", October 2015,
	<http://whois.icann.org/sites/default/files/files/final-		<http://whois.icann.org/sites/default/files/files/final-
	issue-report-next-generation-rds-07oct15-en.pdf>.		issue-report-next-generation-rds-07oct15-en.pdf>.
	[REST] Fielding, R., "Architectural Styles and the Design of
	Network-based Software Architectures", 2000,
	<http://www.ics.uci.edu/~fielding/pubs/dissertation/
	fielding_dissertation.pdf>.
	Appendix A. Paradigms to Enforce Access Control on Reverse Search in		Appendix A. Paradigms to Enforce Access Control on Reverse Search in
	RDAP		RDAP
	Access control can be implemented according to different paradigms		Access control can be implemented according to different paradigms
	introducing increasingly stringent rules. The paradigms reported		introducing increasingly stringent rules. The paradigms reported
	here in the following leverage the capabilities either supported		here in the following leverage the capabilities either supported
	natively or provided as extensions by the OpenID Connect [OIDCC]:		natively or provided as extensions by the OpenID Connect [OIDCC]:
	* Role-Based Access Control: access rights are granted depending on		* Role-Based Access Control: access rights are granted depending on
	roles. Generally, this is done by grouping users into fixed		roles. Generally, this is done by grouping users into fixed
	categories and assigning each category with static grants. A more		categories and assigning static grants to each category. A more
	dynamic approach can be implemented by using the OpenID Connect		dynamic approach can be implemented by using the OpenID Connect
	"scope" claim;		"scope" claim;
	* Purpose-Based Access Control: access rules are based on the notion		* Purpose-Based Access Control: access rules are based on the notion
	of purpose which means the intended usage of some data by a user.		of purpose, being the intended use of some data by a user. It can
	It can be implemented by tagging a request with the usage purpose		be implemented by tagging a request with the usage purpose and
	and making the RDAP server check the compliance between the given		making the RDAP server check the compliance between the given
	purpose and the control rules applied to data to be returned. The		purpose and the control rules applied to the data to be returned.
	purpose can be stated within an out-of-band process by setting the		The purpose can be stated within an out-of-band process by setting
	OpenID Connect RDAP specific "purpose" claim as defined in		the OpenID Connect RDAP-specific "purpose" claim as defined in
	[I-D.ietf-regext-rdap-openid];		[I-D.ietf-regext-rdap-openid];
	* Attribute-Based Access Control: rules to manage access rights are		* Attribute-Based Access Control: rules to manage access rights are
	evaluated and applied according to specific attributes describing		evaluated and applied according to specific attributes describing
	the context within which data are requested. It can be		the context within which data are requested. It can be
	implemented by setting within an out-of-band process additional		implemented by setting within an out-of-band process additional
	OpenID Connect claims describing the request context and making		OpenID Connect claims describing the request context and making
	the RDAP server check the compliance between the given context and		the RDAP server check the compliance between the given context and
	the control rules applied to data to be returned;		the control rules applied to the data to be returned;
	* Time-Based Access Control: data access is allowed for a limited		* Time-Based Access Control: data access is allowed for a limited
	time only. It can be implemented by assigning the users with		time only. It can be implemented by assigning the users with
	temporary credentials linked to access grants whose scope is		temporary credentials linked to access grants whose scope is
	limited.		limited.
	Appendix B. Change Log		Appendix B. Change Log
	00: Initial working group version ported from draft-loffredo-regext-		00: Initial working group version ported from draft-loffredo-regext-
	rdap-reverse-search-04		rdap-reverse-search-04
	01: Updated "Privacy Considerations" section.		01: Updated "Privacy Considerations" section.
	skipping to change at page 12, line 49 ¶		skipping to change at page 12, line 45 ¶
	references. Added Appendix A.		references. Added Appendix A.
	07: Updated normative references.		07: Updated normative references.
	08: Changed "Implementation Status" section. Updated informative		08: Changed "Implementation Status" section. Updated informative
	references.		references.
	09: Extended the query model to represent a reverse search based on		09: Extended the query model to represent a reverse search based on
	any relationship between the RDAP object classes. Changed the		any relationship between the RDAP object classes. Changed the
	path segment "role" into a query parameter.		path segment "role" into a query parameter.
	10: Updated "Reverse Searches Based on Entity Details" section to		10: Updated "Reverse Searches Based on Entity Details" section to
	consider the use of JSContact format instead of jCard. Added		consider the use of JSContact format instead of jCard. Added
	references to JSContact documents.		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.
	Authors' Addresses		Authors' Addresses
	Mario Loffredo		Mario Loffredo
	IIT-CNR/Registro.it		IIT-CNR/Registro.it
	Via Moruzzi,1		Via Moruzzi,1
	56124 Pisa		56124 Pisa
	Italy		Italy
	Email: mario.loffredo@iit.cnr.it		Email: mario.loffredo@iit.cnr.it
	URI: http://www.iit.cnr.it		URI: http://www.iit.cnr.it
	Maurizio Martinelli		Maurizio Martinelli
	IIT-CNR/Registro.it		IIT-CNR/Registro.it
End of changes. 65 change blocks.
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