ENUM -- Telephone Number Mapping                                O. Lendl
Working Group                                                    enum.at
Internet-Draft                                              July 8, 2005
Expires: January 9, 2006


                ENUM Validation Token Format Definition
                  draft-lendl-enum-validation-token-00

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   This Internet-Draft will expire on January 9, 2006.

Copyright Notice

   Copyright (C) The Internet Society (2005).

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.




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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   Unsigned token with registrant information . . . . . . . .  6
     5.3   Signed token . . . . . . . . . . . . . . . . . . . . . . .  7

   6.  Formal Syntax  . . . . . . . . . . . . . . . . . . . . . . . .  9
     6.1   Token Core Schema  . . . . . . . . . . . . . . . . . . . .  9
     6.2   Token Data Schema  . . . . . . . . . . . . . . . . . . . . 11

   7.  Wider applicability  . . . . . . . . . . . . . . . . . . . . . 13

   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13

   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14

   10.   References . . . . . . . . . . . . . . . . . . . . . . . . . 14

       Author's Address . . . . . . . . . . . . . . . . . . . . . . . 15

       Intellectual Property and Copyright Statements . . . . . . . . 16



















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1.  Introduction

   In most cases, the ENUM [2] domain should only be delegated to the
   assignee of the corresponding E.164 number.  In the role model
   described in the architecture draft (work in progress) [9] the entity
   which performs this check is called the Validation Entity (VE).

   The ENUM Validation Token is a signed XML [4] document with which the
   VEs can communicate to the registry over an untrusted path (i.e. the
   Registrar) that the validation issues for a specific delegation
   request have been taken care of.

2.  Data Requirements

   As the data within the Token is the only communication between the VE
   and the registry, a Token needs at a minimum contain as much
   information as the Registry needs to grant the delegation of the
   requested ENUM domain.  The registry itself does not care about the
   actual validation procedure details, it only needs to know that (a)
   an accredited VE has (b) recently (c) successfully validated a
   delegation request for (d) a specific registrar concerning (e) a
   specific E.164 number for (f) which time-span using (g) a specific
   approved method.

   In addition to these necessary information, the Token can also
   contain data about the registrant which the VE has also ascertained
   during the validation procedure.  This additional data about the
   number holder/registrant can the be used to simplify the revalidation
   procedure.

   For example, if the initial validation consists of the steps "Check
   the identity of the registrant" and "Check the ownership of a E.164
   number" then a revalidation needs only check the second part again.

   As the Token will be included in XML-based registry/registrar
   protocols like EPP it is a natural choice to use XML to encode
   Validation Tokens.

3.  Digital Signature

   There is a trust relationship between the registry and the VE, but no
   direct, secured communication link.  The Token will be submitted to
   the registry as part of the delegation request by the registrar who
   is not necessarily trusted by the registry regarding validation
   issues.

   It is also possible that a VE does not directly talk with the
   registrar, but instead only interacts with the registrant and hands



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   the Token to him.

   Given these untrusted paths, the Token needs to be protected from
   tampering on its way from the VE to the registry.  Furthermore, the
   registry needs to be sure that the Token was indeed created by the VE
   noted inside the Token.

   A digital signature on the token guarantees that
   o  the token was indeed generated by the indicated VE (authenticity)
   o  the token was not tampered with in transit (integrity)
   o  auditing the validation process is possible (non-repudiation).

   The cryptographic signature on the token follows XML-DSIG [7].  As
   tokens might be transmitted as part of an already XML based protocol
   the transform as specified in [8] is used.  In order to make the
   signature an integral part of the token the "enveloped"-signature
   mode is employed.  The actual signature uses the RSA-SHA1 algorithm
   and relies on X.509 certificates.  The signature covers all
   information contained in the Token.

   This document does not assume a public key infrastructure.  Whether
   the registry acts as a certificate authority, accepts certs from a
   public CA, or only accepts pre-registered keys is a local policy
   choice.  Including certificates within the signature is recommended
   as this makes checking the signature possible without references to
   external information.

4.  Field Descriptions

4.1  Mandatory Section

   A token must contain a <validation> tag which contains the following:
   o  A single validation "serial" string uniquely identifying a
      validation token for a certain VE.
   o  A single "e164number" attribute, containing the E.164 number in
      international format for which validation was carried out.
   o  A single "validator" id, identifying the VE.
   o  A single "method" id, identifying the method used by the VE for
      validation.
   o  A single "registrar" id, identifying the registrar for which
      validation was carried out.
   o  A single "createdate" attribute, containing the date of
      validation, formatted as "full-date" according to RFC3339 [3].
   o  A single "expiredate" attribute, marking the expiration date of
      the validation token, formatted as "full-date" according to
      RFC3339.  This is the only optional attribute in this section.  A
      missing expiredate signifies that this ENUM domain does not need
      to undergo regular revalidation procedures.



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4.2  Optional Section

   A token MAY contain a "tokendata" section.  The section contains
   information about the entity whose right-to-use is being asserted.
   o  A single "organization" attribute, containing the full name of the
      entity.
   o  A single "commercialregisternumber" attribute, containing the
      entity's registration number.
   o  A single "title" attribute.
   o  A single "firstname" attribute.
   o  A single "lastname" attribute.
   o  A single "address" section, containing the following attributes:
      *  A single mandatory "streetname" attribute
      *  A single optional "streetnumber" attribute
      *  A single optional "apartment" attribute
      *  A single mandatory "postalcode" attribute
      *  A single mandatory "city" attribute
      *  A single optional "state" attribute
      *  A single mandatory "country" attribute
   o  up to 10 "phone" attributes, containing full E.164 numbers
   o  up to 10 "fax" attributes, containing full E.164 numbers
   o  up to 10 "email" attributes

   Basically, all attributes are optional.  In case an address section
   is used, several components are mandatory for conformance with the
   E.115 [1] recommendation.  The reason for this is that "computerized
   directory assistance" accessible through the E.115 interface may be a
   source of validation information.

5.  Examples

5.1  Unsigned token without registrant information

   This is the basic Token without any information about the registrant
   and without the cryptographic signature.
















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   <?xml version="1.0" encoding="utf-8" standalone="no" ?>
   <token xmlns="http://www.enum.at/rxsd/enum-token-1.1" Id="TOKEN"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation=
       "http://www.enum.at/rxsd/enum-token-1.1 enum-token-1.1.xsd">
     <validation serial="1">
       <e164number>+431987654321</e164number>
       <validator>AcmeVE</validator>
       <registrarid>bigITSP</registrarid>
       <method>1</method>
       <createdate>2005-07-08</createdate>
       <expiredate>2006-01-01</expiredate>
     </validation>
   </token>



5.2  Unsigned token with registrant information

































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   <?xml version="1.0" encoding="utf-8" standalone="no" ?>
   <token xmlns="http://www.enum.at/rxsd/enum-token-1.1" Id="TOKEN"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation=
       "http://www.enum.at/rxsd/enum-token-1.1 enum-token-1.1.xsd">
     <validation serial="1">
       <e164number>+431987654321</e164number>
       <validator>AcmeVE</validator>
       <registrarid>bigITSP</registrarid>
       <method>1</method>
       <createdate>2005-07-08</createdate>
       <expiredate>2006-01-01</expiredate>
     </validation>
     <tokendata xmlns="http://www.enum.at/rxsd/enum-tokendata-1.1"
        xsi:schemaLocation=
       "http://www.enum.at/rxsd/enum-tokendata-1.1 enum-tokendata-1.1.xsd">
       <contact>
         <organisation>Example Corp.</organisation>
         <firstname>Peter</firstname>
         <lastname>Mustermann</lastname>
         <address>
           <streetname>Elm Street</streetname>
           <streetnumber>3</streetnumber>
           <postalcode>1010</postalcode>
           <city>Wien</city>
           <country>AT</country>
         </address>
         <email>pm@example.com</email>
       </contact>
     </tokendata>
   </token>



5.3  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.


   <?xml version="1.0" encoding="utf-8" standalone="no" ?>
   <token xmlns="http://www.enum.at/rxsd/enum-token-1.1" Id="TOKEN"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation=
       "http://www.enum.at/rxsd/enum-token-1.1 enum-token-1.1.xsd">
     <validation serial="1">
       <e164number>+431987654321</e164number>



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       <validator>AcmeVE</validator>
       <registrarid>bigITSP</registrarid>
       <method>1</method>
       <createdate>2005-07-08</createdate>
       <expiredate>2006-01-01</expiredate>
     </validation>
     <tokendata xmlns="http://www.enum.at/rxsd/enum-tokendata-1.1"
     xsi:schemaLocation=
     "http://www.enum.at/rxsd/enum-tokendata-1.1 enum-tokendata-1.1.xsd">
       <contact>
         <organisation>Example Corp.</organisation>
         <firstname>Peter</firstname>
         <lastname>Mustermann</lastname>
         <address>
           <streetname>Elm Street</streetname>
           <streetnumber>3</streetnumber>
           <postalcode>1010</postalcode>
           <city>Wien</city>
           <country>AT</country>
         </address>
         <email>pm@example.com</email>
       </contact>
     </tokendata>
     <Signature xmlns="http://www.w3.org/2000/09/xmldsig#">
       <SignedInfo>
         <CanonicalizationMethod Algorithm=
           "http://www.w3.org/2001/10/xml-exc-c14n#"/>
         <SignatureMethod Algorithm=
           "http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
         <Reference URI="#TOKEN">
           <Transforms>
             <Transform Algorithm=
               "http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
             <Transform Algorithm=
               "http://www.w3.org/2001/10/xml-exc-c14n#">
               <InclusiveNamespaces xmlns=
                 "http://www.w3.org/2001/10/xml-exc-c14n#"
                 PrefixList="enum-token enum-tokendata"/>
             </Transform>
           </Transforms>
           <DigestMethod Algorithm=
             "http://www.w3.org/2000/09/xmldsig#sha1"/>
           <DigestValue>gtgIo5RnM5i0fkOKxP8otc0/YrA=</DigestValue>
         </Reference>
       </SignedInfo>
       <SignatureValue>WATnADceCRKMQU/b9h4U8efoDe7zInxYj2+5R5aghKNy5pMYsCjV+2M8LxFyBJhk
   z3fvw8ulheEcXOxj+Ih4qavbrmW9BgRWFPSiTSby+S2fm9zYjdWkCePuvxJUor89
   w6lHYylWGt2gCuXHfjv68uI/qD5HssxkSbmqALj9A8k=</SignatureValue>



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     <KeyInfo>
   <X509Data>
   <X509Certificate>MIIDZjCCAs+gAwIBAgIBBDANBgkqhkiG9w0BAQQFADB0MQswCQYDVQQGEwJBVDEP
   MA0GA1UEBxMGVmllbm5hMRQwEgYDVQQKEwtCT0ZIIENlcnRzLjEbMBkGA1UEAxMS
   Q0VSVFMuYm9maC5wcml2LmF0MSEwHwYJKoZIhvcNAQkBFhJjZXJ0c0Bib2ZoLnBy
   aXYuYXQwHhcNMDQwNzIwMTMxNTA5WhcNMDUwNzIwMTMxNTA5WjB/MQswCQYDVQQG
   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==
   </X509Certificate>
   </X509Data>
   </KeyInfo>
   </Signature>
   </token>



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.

6.1  Token Core Schema


   <?xml version="1.0" encoding="UTF-8"?>

     <schema targetNamespace="http://www.enum.at/rxsd/enum-token-1.1"
             xmlns:enum-token="http://www.enum.at/rxsd/enum-token-1.1"
             xmlns:enum-tokendata="http://www.enum.at/rxsd/enum-tokendata-1.1"
             xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
             xmlns="http://www.w3.org/2001/XMLSchema"
             elementFormDefault="qualified">




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     <!--  Import common element types.  -->

       <import namespace="http://www.w3.org/2000/09/xmldsig#"
               schemaLocation="xmldsig-core-schema.xsd"/>
       <import namespace="http://www.enum.at/rxsd/enum-tokendata-1.1"
               schemaLocation="enum-tokendata-1.1.xsd"/>

       <annotation>
         <documentation>
           enum.at Validation Token core schema
         </documentation>
       </annotation>

       <element name="token" type="enum-token:tokenBaseType"/>

       <simpleType name="shortTokenType">
         <restriction base="token">
           <minLength value="1"/>
           <maxLength value="20"/>
         </restriction>
       </simpleType>

       <simpleType name="e164numberType">
         <restriction base="token">
           <maxLength value="64"/>
           <pattern value="\+\s*\d\d\s*[\s\d]{1,}"/>
         </restriction>
       </simpleType>

       <complexType name="validationDataType">
         <sequence>
           <element name="e164number"  type="enum-token:e164numberType"/>
           <element name="validator"   type="enum-token:shortTokenType"/>
           <element name="registrarid" type="enum-token:shortTokenType"/>
           <element name="method"      type="enum-token:shortTokenType"/>
           <element name="createdate"  type="date"/>
           <element name="expiredate"  type="date" minOccurs="0"/>
         </sequence>
         <attribute name="serial" type="enum-token:shortTokenType"
          use="required"/>
       </complexType>

       <complexType name="tokenBaseType">
         <sequence>
           <element name="validation" type="enum-token:validationDataType"/>
           <any namespace="http://www.enum.at/rxsd/enum-tokendata-1.1"
            minOccurs="0"/>
           <any namespace="http://www.w3.org/2000/09/xmldsig#"/>



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         </sequence>
         <attribute name="Id" type="ID" use="required"/>
       </complexType>

       <complexType name="infDataContainerType">
         <sequence>
           <element name="infData" type="enum-token:tokenBaseType"/>
         </sequence>
       </complexType>

     </schema>



6.2  Token Data Schema

   <?xml version="1.0" encoding="UTF-8"?>

     <schema targetNamespace="http://www.enum.at/rxsd/enum-tokendata-1.1"
             xmlns:enum-tokendata="http://www.enum.at/rxsd/enum-tokendata-1.1"
             xmlns="http://www.w3.org/2001/XMLSchema"
             elementFormDefault="qualified">

       <annotation>
         <documentation>
           enum.at Validation Token tokendata schema.
         </documentation>
       </annotation>

       <element name="tokendata" type="enum-tokendata:tokenDataType"/>

       <simpleType name="streetNameType">
         <restriction base="token">
           <minLength value="1"/>
           <maxLength value="128"/>
         </restriction>
       </simpleType>

       <simpleType name="shortTokenType">
         <restriction base="token">
           <minLength value="1"/>
           <maxLength value="20"/>
         </restriction>
       </simpleType>

       <simpleType name="longTokenType">
         <restriction base="token">
           <minLength value="1"/>



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           <maxLength value="64"/>
         </restriction>
       </simpleType>

       <complexType name="addressType">
         <sequence>
           <element name="streetname"   type="enum-tokendata:streetNameType"/>
           <element name="streetnumber" type="enum-tokendata:shortTokenType"
            minOccurs="0"/>
           <element name="apartment"    type="enum-tokendata:shortTokenType"
            minOccurs="0"/>
           <element name="postalcode"   type="enum-tokendata:shortTokenType"/>
           <element name="city"         type="enum-tokendata:longTokenType"/>
           <element name="state"        type="enum-tokendata:longTokenType"
            minOccurs="0"/>
           <element name="country"      type="enum-tokendata:longTokenType"/>
         </sequence>
       </complexType>

       <group name="tokenContactBaseGroup">
         <sequence>
           <element name="organisation" type="enum-tokendata:shortTokenType"
            minOccurs="0"/>
           <element name="commercialregisternumber"
            type="enum-tokendata:shortTokenType" minOccurs="0"/>
           <element name="title"     type="enum-tokendata:shortTokenType"
            minOccurs="0"/>
           <element name="firstname" type="enum-tokendata:longTokenType"
            minOccurs="0"/>
           <element name="lastname"  type="enum-tokendata:longTokenType"
            minOccurs="0"/>
           <element name="address"   type="enum-tokendata:addressType"
            minOccurs="0"/>
           <element name="phone"     type="enum-tokendata:shortTokenType"
            minOccurs="0" maxOccurs="10" />
           <element name="fax"       type="enum-tokendata:shortTokenType"
            minOccurs="0" maxOccurs="10" />
           <element name="email"     type="enum-tokendata:shortTokenType"
            minOccurs="0" maxOccurs="10" />
         </sequence>
       </group>

       <complexType name="contactType">
         <sequence>
           <group ref="enum-tokendata:tokenContactBaseGroup"/>
         </sequence>
       </complexType>




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       <complexType name="tokenDataType">
         <sequence>
           <element name="contact" type="enum-tokendata:contactType"/>
         </sequence>
       </complexType>

     </schema>


7.  Wider applicability

   The basic idea of this validation token can be helpful to other
   registries where any request for a delegation must be accompanied by
   a proof of ownership.

   One example are all the specialized TLDs with strict rules on who
   qualifies for registering a domain under that TLD.

   Even liberal TLDs could make use of validation tokens during a
   sunrise phase, where only applicants with a prior right to a name are
   allowed to register a domain.

   Moving away from a the domain business, the telephone number
   portability verification needs to solve roughly the same validation
   problem as the ENUM domain delegation.  A formalized system based on
   signed tokens could replace the manual process used in many
   countries.

8.  Security Considerations

   The security of this Tokens depends on the security of the underlying
   XML DSIG algorithms.  As such, all the security considerations from
   [7] apply here as well.  Two points from there need special
   attention:

   Transforms can be used to select the relevant data for signing and to
   discard irrelevant information (e.g. pretty-printing and name-space
   local names).  They need to be selected with care.

   The <Reference URI="#TOKEN"> element and attribute combined with the
   Id="TOKEN" attribute in <token> specifies that the signature should
   cover the complete token.  Moving the Id="TOKEN" attribute to e.g.
   the <tokendata> tag would make the signature worthless.

   It is thus critical that the registry does not only check whether the
   Token passes a generic XML-SEC signature check, but also that the
   signature uses approved transforms and references the <token> tag as
   well as that the certificate belongs to an accredited VE.



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   The Token is not encrypted.  If local policy dictates that the
   information contained within the token should be protected then this
   has to be handled via other means.

   When processing a delegation request the registry needs to make sure
   that the information within the Token matches the delegation request.
   To avert replay attacks, local policy has to specify how long after
   "createdate" the Token remains valid.

9.  Acknowledgements

   The author would like to thank the following persons for their
   valuable suggestions and contributions: Michael Haberler, Alexander
   Mayrhofer, Michael Braunoeder

10.  References

   [1]  ITU-T, "Computerized Directory Assistance",
        Recommendation E.115, February 1995.

   [2]  Faltstrom, P. and M. Mealling, "The E.164 to Uniform Resource
        Identifiers (URI) Dynamic Delegation Discovery System (DDDS)
        Application (ENUM)", RFC 3761, April 2004.

   [3]  Klyne, G. and C. Newman, "Date and Time on the Internet:
        Timestamps", RFC 3339, July 2002.

   [4]  Paoli, J., Sperberg-McQueen, C., Bray, T., and E. Maler,
        "Extensible Markup Language (XML) 1.0 (Second Edition)", W3C
        FirstEdition REC-xml-20001006, October 2000.

   [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]  Solo, D., Reagle, J., and D. Eastlake, "XML-Signature Syntax and
        Processing", W3C REC REC-xmldsig-core-20020212, February 2002.

   [8]  3rd, D., Boyer, J., and J. Reagle, "Exclusive XML
        Canonicalization Version 1.0", W3C REC REC-xml-exc-c14n-
        20020718, July 2002.

   [9]  Mayrhofer and Hoeneisen, "ENUM Validation Architecture",
        Internet
        drafts (draft-mayrhofer-enum-validation-architecture-00.txt),



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        July 2005.


Author's Address

   Otmar Lendl
   enum.at GmbH
   Karlsplatz 1/9
   Wien  A-1010
   Austria

   Phone: +43 1 5056416 33
   Email: otmar.lendl@enum.at
   URI:   http://www.enum.at/





































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