ENUM -- Telephone Number Mapping O. Lendl Working Group enum.at Internet-Draft February 22, 2006 Expires: August 26, 2006 ENUM Validation Token Format Definition draft-ietf-enum-validation-token-02 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on August 26, 2006. Copyright Notice Copyright (C) The Internet Society (2006). Abstract An ENUM domain name is tightly coupled with the underlying E.164 number. The process of verifying whether the Registrant of an ENUM domain name is identical to the Assignee of the corresponding E.164 number is commonly called "validation". This document describes an signed XML data format -- the Validation Token -- with which Validation Entities can convey successful completion of a validation procedure in a secure fashion. Lendl Expires August 26, 2006 [Page 1] Internet-Draft ENUM Validation Token February 2006 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Data Requirements . . . . . . . . . . . . . . . . . . . . . 3 3. Digital Signature . . . . . . . . . . . . . . . . . . . . . 3 4. Field Descriptions . . . . . . . . . . . . . . . . . . . . . 4 4.1 Mandatory Section . . . . . . . . . . . . . . . . . . . . 4 4.2 Optional Section . . . . . . . . . . . . . . . . . . . . . 5 5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5.1 Unsigned Token without Registrant Information . . . . . . 5 5.2 Signed token . . . . . . . . . . . . . . . . . . . . . . . 6 6. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . 8 6.1 Token Core Schema . . . . . . . . . . . . . . . . . . . . 8 6.2 Token Data Schema . . . . . . . . . . . . . . . . . . . . 10 7. Other applications of the Token concept . . . . . . . . . . 12 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . 12 9. Security Considerations . . . . . . . . . . . . . . . . . . 13 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 11.1 Normative References . . . . . . . . . . . . . . . . . . 14 11.2 Informative References . . . . . . . . . . . . . . . . . 14 Author's Address . . . . . . . . . . . . . . . . . . . . . . 15 Intellectual Property and Copyright Statements . . . . . . . 16 Lendl Expires August 26, 2006 [Page 2] Internet-Draft ENUM Validation Token February 2006 1. Introduction In the case where an ENUM (E.164 Number Mapping [1]) domain name corresponds to an existing E.164 number [2] the delegation of this domain needs to be authorized by the Assignee of the corresponding E.164 number. In the role model described in [11] the entity which performs this check is called the Validation Entity (VE). By conveying an ENUM Validation Token - a signed XML document - to the Registry a VE certifies that delegation requirements have been met and are current. 2. Data Requirements In this model, the Token is the only piece of data passed from the VE to the Registry. Therefore, the Token needs to contain as least as much information as the Registry requires to grant the delegation of the requested ENUM domain according to its registration policy. As such, the Registry will need confirmation that o the Token was created by an accredited VE, o the Token's duration of validity conforms to the policy, o the validation procedure employed has met minimum requirements as set forth by policy, o and that the Token is protected against tampering and replay attacks. Beyond such mandatory information, the Token may optionally include number holder information, in particular to simplify future re- validations. For example, if initial validation requires the steps "Check the identity of the Registrant" and "Check the ownership of an E.164 number" then a later revalidation only needs to re-check the ownership as the identity of the Registrant does not change. As the Token will be included (see e.g. [12]) in XML-based Registry/ Registrar protocols like the Extensible Provisioning Protocol (EPP) [9] it is a natural choice to use XML to encode Validation Tokens. 3. Digital Signature According to the architecture model the propriety of an ENUM delegation depends on the trust relationship between the Registry and the VE. For generality, an untrusted link between Registry and VE should be assumed (for instance the Token is passed along with the registration request by a Registrar, who might have no role in asserting the right-to-use). Therefore, the Token must be protected against forgery, tampering and replay-attacks. Lendl Expires August 26, 2006 [Page 3] Internet-Draft ENUM Validation Token February 2006 A digital signature on the token o asserts that the token was indeed generated by the indicated VE (authenticity) o guarantees that the token was not tampered with in transit (integrity) o enables auditing the validation process (non-repudiation). The cryptographic signature on the token follows RFC 3275 (XML-DSIG [3]). As tokens might be transmitted as part of an already XML based protocol the exclusive XML canonicalization [7] is used. This transform guarantees that namespace declarations inherited from the surrounding XML do not invalidate the signature. In order to make the signature an integral part of the token the "enveloped"-signature mode is employed. The signature covers all information contained in the Token. While XML-DSIG offers a number of cryptographic algorithms, local policy should define which algorithms will be accepted by the Registry. It is suggested to use the RSA-SHA1 algorithm with embedded X.509 [8] certificates. The choice of RSA-SHA1 does not require a public key infrastructure. Whether the Registry acts as a certificate authority, accepts certs from a public Certification Authority, or only accepts pre-registered keys is a local policy choice. 4. Field Descriptions 4.1 Mandatory Section A token must contain a element which contains the following: o A single validation "serial" attribute identifying a validation token for a certain VE. It must be unique per VE. o A single element containing the underlying E.164 number in fully qualified (international) format. o An optional element. If present it indicates that the whole number block starting with up to and including has been validated. To avoid ambiguity, both numbers must be of the same length. o A single element identifying the VE. o A single element identifying the Registrar on whose behalf the validation was performed. o A single element identifying the method used by the VE for validation. o A single attribute containing the date of validation formatted as "full-date" according to RFC 3339 [4]. Lendl Expires August 26, 2006 [Page 4] Internet-Draft ENUM Validation Token February 2006 o An optional attribute marking the expiration date of the validation token formatted as "full-date" according to RFC 3339. The Registry will automatically revoke the delegation at this date unless a new Token has been submitted that extends the lifetime of the validation. A missing expirationDate indicates infinite validity of the Token. The format and the uniqueness-constraints of these IDs is left to the local policy of the Registry. 4.2 Optional Section A token may contain a section containing information about the number holder, consisting of the the following elements: o A single element containing the full name of the organization to which the Registrant is affiliated. o A single element. If the Registrant is a company, then this field can be used to uniquely identify that company by its official registration number. The interpretation of this field is country-specific. o A single element o A single <firstname> element o A single <lastname> element o A single <address> section containing the following elements: * A single optional <streetName> * A single optional <houseNumber> * A single optional <postalCode> * A single optional <locality> * A single optional <countyStateOrProvince> * A single optional <ISOcountryCode> o up to 10 <phone> elements containing full E.164 numbers o up to 10 <fax> elements containing full E.164 numbers o up to 10 <email> elements All elements directly under <tokendata> are optional. The first five elements within the <address> element conform to the second version of the E.115 Computerized Directory Assistance [14]. The <ISOcountryCode> element specifies the country using the ISO 3166 [13] code. 5. Examples 5.1 Unsigned Token without Registrant Information This basic Token without any information about the Registrant and without the cryptographic signature shows the basic layout of the mandatory elements. Lendl Expires August 26, 2006 [Page 5] Internet-Draft ENUM Validation Token February 2006 <?xml version="1.0" encoding="utf-8" standalone="no" ?> <token xmlns="urn:ietf:params:xml:ns:enum-token-1.0" Id="TOKEN" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation= "urn:ietf:params:xml:ns:enum-token-1.0 enum-token-1.0.xsd"> <validation serial="acmeve-000002"> <E164Number>+43780000000</E164Number> <lastE164Number>+43780000099</lastE164Number> <validationEntityID>ACME-VE</validationEntityID> <registrarID>reg-4711</registrarID> <methodID>42</methodID> <executionDate>2006-02-24</executionDate> <expirationDate>2006-11-01</expirationDate> </validation> </token> 5.2 Signed token This example uses an X.509 based signature which includes the certificate of the signing validation entity. Thus the validity of the signature can be verified without the need for a key-server. A valid signature is a necessary, but not sufficient condition for a valid Token. Any entity evaluating a Token needs to check other factors as well, e.g. the certificate and the XML schema. <?xml version="1.0" encoding="utf-8" standalone="no" ?> <token xmlns="urn:ietf:params:xml:ns:enum-token-1.0" Id="TOKEN" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation= "urn:ietf:params:xml:ns:enum-token-1.0 enum-token-1.0.xsd"> <validation serial="acmeve-000001"> <E164Number>+43780837800</E164Number> <validationEntityID>ACME-VE</validationEntityID> <registrarID>reg-4711</registrarID> <methodID>42</methodID> <executionDate>2006-02-25</executionDate> </validation> <tokendata xmlns="urn:ietf:params:xml:ns:enum-tokendata-1.0" xsi:schemaLocation= "urn:ietf:params:xml:ns:enum-tokendata-1.0 enum-tokendata-1.0.xsd"> <contact> <organisation>Example GmbH</organisation> <commercialregisternumber>4711</commercialregisternumber> Lendl Expires August 26, 2006 [Page 6] Internet-Draft ENUM Validation Token February 2006 <title>Dr. Max Mustermann
Hauptplatz 10 1010 Wien Wien AT
+43101234567 mm@example.com
2IYulFcDeq37i35u+VMMgC060mk= JvGNBH6zKobpydfrIkqiKLOx32Bl+g3nKocoqWkS8u7FiWcEQdEWvvsjt8Itt13F Lecjd4TlDb/GrgC1lHW3fYTP1/bAXYKiceZ9XWmAC5m3bqfoLgFPDekZhQzCB+nx YzNrsOE3ktwVCOgFkTmOBszJXu6Kv2JFGXbmBXsGgYA= MIIDZjCCAs+gAwIBAgIBBDANBgkqhkiG9w0BAQQFADB0MQswCQYDVQQGEwJBVDEP MA0GA1UEBxMGVmllbm5hMRQwEgYDVQQKEwtCT0ZIIENlcnRzLjEbMBkGA1UEAxMS Q0VSVFMuYm9maC5wcml2LmF0MSEwHwYJKoZIhvcNAQkBFhJjZXJ0c0Bib2ZoLnBy aXYuYXQwHhcNMDQwNzIwMTMxNTA5WhcNMDUwNzIwMTMxNTA5WjB/MQswCQYDVQQG Lendl Expires August 26, 2006 [Page 7] Internet-Draft ENUM Validation Token February 2006 EwJBVDEKMAgGA1UECBMBLTEPMA0GA1UEBxMGVmllbm5hMR0wGwYDVQQKExRBY21l IEVOVU0gVmFsaWRhdGlvbjEQMA4GA1UEAxMHYWNtZS1WRTEiMCAGCSqGSIb3DQEJ ARYTbm9ib2R5QGVudW0tYWNtZS5hdDCBnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkC gYEArJPcjMFc54/zwztSdQXGxUtodJT9r1qGI2lQPNjLvtPJg93+7o5SIOsZGSpg zWbztDAV5qc7PHZWUVIyf6MbM5qSgQDVrjNRhTosNtyqmwi23BH52SKkX3P7eGit LmqEkiUZRxZhZ6upRbtcqvKSwmXitvW4zXZhkVHYJZ2HuMcCAwEAAaOB/DCB+TAJ BgNVHRMEAjAAMCwGCWCGSAGG+EIBDQQfFh1PcGVuU1NMIEdlbmVyYXRlZCBDZXJ0 aWZpY2F0ZTAdBgNVHQ4EFgQUyK4otTQtvv6KdSlMBOPT5Ve18JgwgZ4GA1UdIwSB ljCBk4AUvfPadpm0HhmZx2iAVumQTwgnG2eheKR2MHQxCzAJBgNVBAYTAkFUMQ8w DQYDVQQHEwZWaWVubmExFDASBgNVBAoTC0JPRkggQ2VydHMuMRswGQYDVQQDExJD RVJUUy5ib2ZoLnByaXYuYXQxITAfBgkqhkiG9w0BCQEWEmNlcnRzQGJvZmgucHJp di5hdIIBADANBgkqhkiG9w0BAQQFAAOBgQCB9CHBnIUhrdic4h5Ar4hdxjHSQkDH sJWd+MYrNcuSrv3TIOsUkUgNpNNhmkZPtiXqfy3388IRdJtJiLWXSOb/XlZHOM9I MvwKYwhcpQ9UdM/w7VpXQqf+CEj0XSyqxGw65UsHIOijgiG/WyhSj+Lzriw7CTge P2iAJkJVC4t2XA== 6. Formal Syntax The formal syntax of the validation token is specified using XML schema notation [5] [6]. Two schemas are defined: The "token core schema" contains mandatory attribute definitions, the "token data schema" defines the format of the optional "tokendata" section. The BEGIN and END tags are not part of the schema; they are used to note the beginning and ending of the schema for URI registration purposes. 6.1 Token Core Schema BEGIN Lendl Expires August 26, 2006 [Page 8] Internet-Draft ENUM Validation Token February 2006 enum.at Validation Token core schema END 6.2 Token Data Schema BEGIN Lendl Expires August 26, 2006 [Page 10] Internet-Draft ENUM Validation Token February 2006 Lendl Expires August 26, 2006 [Page 11] Internet-Draft ENUM Validation Token February 2006 END 7. Other applications of the Token concept The concept of the validation token may be useful in other registry- type applications where the proof of an underlying right is a condition for a valid registration. An example is a TLD (Top Level Domain) where registration is subject to proof of some precondition, like a trade mark or the right in a name. Such situations often arise during the introduction of a new TLD, e.g. during a "sunrise" phase. A Number Portability (NP) database faces very similar verification issues. An NP system based on the Token concept could potentially be superior to current methods, and aid in the convergence of NP and ENUM. 8. IANA Considerations This document uses URNs to describe XML namespaces and XML schemas conforming to a registry mechanism described in RFC 3688 [10]. Four URI assignments are requested. 1. Registration request for the Token namespace: * URI: urn:ietf:params:xml:ns:enum-token-1.0 * Registrant Contact: See the "Author's Address" section of this document. * XML: None. Namespace URIs do not represent an XML specification. 2. Registration request for the Token XML schema: * URI: urn:ietf:params:xml:schema:enum-token-1.0 * Registrant Contact: See the "Author's Address" section of this document. * XML: See Section 6.1 of this document. 3. Registration request for the Token Data namespace: * URI: urn:ietf:params:xml:ns:enum-tokendata-1.0 * Registrant Contact: See the "Author's Address" section of this document. Lendl Expires August 26, 2006 [Page 12] Internet-Draft ENUM Validation Token February 2006 * XML: None. Namespace URIs do not represent an XML specification. 4. Registration request for the Token Data XML schema: * URI: urn:ietf:params:xml:schema:enum-tokendata-1.0 * Registrant Contact: See the "Author's Address" section of this document. * XML: See Section 6.2 of this document. The IDs used in the validationEntityID, RegistrarID, and methodID elements are subject to local policy and thus do not require IANA registration. 9. Security Considerations The security of the Validation Token depends on the security of the underlying XML DSIG algorithms. As such, all the security considerations from [3] apply here as well. Two points from there merit repetition: Transforms are used to select the relevant data for signing and to discard irrelevant information (e.g. pretty-printing and name-space local names). The element and attribute combined with the Id="TOKEN" attribute in specifies that the signature should cover the complete token. Moving the Id="TOKEN" attribute to e.g. the element would make the signature worthless. It is thus critical that the Registry does not only check whether the Token passes a generic XML-DSIG signature check, but also that the signature uses approved transforms and references the element as well as that the certificate belongs to an accredited VE. The Token content is not encrypted. If local policy dictates that the information contained within the token should be protected then this has to be handled through a different mechanism. When processing a delegation request the Registry must verify that the information contained in the Token matches the delegation request. To avert replay attacks, local policy has to specify for how long after the Token can be used to authorize a delegation. The element in the Token prevents a malicious second Registrar from using an eavesdropped Token to register a domain in his name. 10. Acknowledgements The author would like to thank the following persons for their Lendl Expires August 26, 2006 [Page 13] Internet-Draft ENUM Validation Token February 2006 valuable suggestions and contributions: Michael Haberler, Alexander Mayrhofer, Bernie Hoeneisen, Michael Braunoeder, Staffan Hagnell, Lawrence Conroy, Tony Rutkowski. 11. References 11.1 Normative References [1] Faltstrom, P. and M. Mealling, "The E.164 to Uniform Resource Identifiers (URI) Dynamic Delegation Discovery System (DDDS) Application (ENUM)", RFC 3761, April 2004. [2] ITU-T, "The international public telecommunication numbering plan", Recommendation E.164, May 1997. [3] Eastlake, D., Reagle, J., and D. Solo, "(Extensible Markup Language) XML-Signature Syntax and Processing", RFC 3275, March 2002. [4] Klyne, G. and C. Newman, "Date and Time on the Internet: Timestamps", RFC 3339, July 2002. [5] Maloney, M., Beech, D., Mendelsohn, N., and H. Thompson, "XML Schema Part 1: Structures", W3C REC REC-xmlschema-1-20010502, May 2001. [6] Malhotra, A. and P. Biron, "XML Schema Part 2: Datatypes", W3C REC REC-xmlschema-2-20010502, May 2001. [7] 3rd, D., Boyer, J., and J. Reagle, "Exclusive XML Canonicalization Version 1.0", W3C REC REC-xml-exc-c14n- 20020718, July 2002. [8] International Telecommunications Union, "Information technology - Open Systems Interconnection - The Directory: Public-key and attribute certificate frameworks", ITU-T Recommendation X.509, ISO Standard 9594-8, March 2000. 11.2 Informative References [9] Hollenbeck, S., "Extensible Provisioning Protocol (EPP)", RFC 3730, March 2004. [10] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January 2004. [11] Mayrhofer, A. and B. Hoeneisen, "ENUM Validation Architecture", draft-ietf-enum-validation-arch-01 (work in progress), Lendl Expires August 26, 2006 [Page 14] Internet-Draft ENUM Validation Token February 2006 February 2006. [12] Hoeneisen, B., "ENUM Validation Information Mapping for the Extensible Provisioning Protocol", draft-ietf-enum-validation-epp-02 (work in progress), February 2006. [13] International Organization for Standardization, "Codes for the representation of names of countries, 3rd edition", ISO Standard 3166, August 1988. [14] ITU-T, "Computerized Directory Assistance Version 2", Recommendation E.115v2, October 2005. Author's Address Otmar Lendl enum.at GmbH Karlsplatz 1/2/9 Wien A-1010 Austria Phone: +43 1 5056416 33 Email: otmar.lendl@enum.at URI: http://www.enum.at/ Lendl Expires August 26, 2006 [Page 15] Internet-Draft ENUM Validation Token February 2006 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. 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Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2006). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Lendl Expires August 26, 2006 [Page 16]