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Versions: 00 draft-ietf-sidr-signed-object

Secure Inter-Domain Routing                                  M. Lepinski
Internet-Draft                                                    A. Chi
Intended status: Standards Track                                 S. Kent
Expires: February 21, 2011                                           BBN
                                                         August 20, 2010


   Signed Object Template for the Resource Public Key Infrastructure
                  draft-achi-rpki-signed-object-00.txt

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on February 21, 2011.

Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Abstract

   This document defines a generic profile for signed objects used in
   the Resource Public Key Infrastructure.  These RPKI signed objects
   make use of Cryptographic Message Syntax (CMS) as a standard
   encapsulation format.



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Table of Contents

   1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3
      1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
      1.2. Note on Algorithms  . . . . . . . . . . . . . . . . . . . . 3
   2. Signed Object Syntax . . . . . . . . . . . . . . . . . . . . . . 4
      2.1. Signed-Data Content Type  . . . . . . . . . . . . . . . . . 4
         2.1.1. version  . . . . . . . . . . . . . . . . . . . . . . . 4
         2.1.2. digestAlgorithms . . . . . . . . . . . . . . . . . . . 4
         2.1.3. encapContentInfo . . . . . . . . . . . . . . . . . . . 5
            2.1.3.1. eContentType  . . . . . . . . . . . . . . . . . . 5
            2.1.3.2. eContent  . . . . . . . . . . . . . . . . . . . . 5
         2.1.4. certificates . . . . . . . . . . . . . . . . . . . . . 5
         2.1.5. crls . . . . . . . . . . . . . . . . . . . . . . . . . 5
         2.1.6. signerInfos  . . . . . . . . . . . . . . . . . . . . . 6
            2.1.6.1. version . . . . . . . . . . . . . . . . . . . . . 6
            2.1.6.2. sid . . . . . . . . . . . . . . . . . . . . . . . 6
            2.1.6.3. digestAlgorithm . . . . . . . . . . . . . . . . . 6
            2.1.6.4. signedAttrs . . . . . . . . . . . . . . . . . . . 6
               2.1.6.4.1. Content-Type Attribute . . . . . . . . . . . 7
               2.1.6.4.2. Message-Digest Attribute . . . . . . . . . . 7
               2.1.6.4.3. SigningTime Attribute  . . . . . . . . . . . 7
               2.1.6.4.4. BinarySigningTime Attribute  . . . . . . . . 8
            2.1.6.5. signatureAlgorithm  . . . . . . . . . . . . . . . 8
            2.1.6.6. signature . . . . . . . . . . . . . . . . . . . . 8
            2.1.6.7. unsignedAttrs . . . . . . . . . . . . . . . . . . 8
   3. Signed Object Validation . . . . . . . . . . . . . . . . . . . . 9
   4. Definition of Specific Signed Objects  . . . . . . . . . . . .  10
   5. Security Considerations  . . . . . . . . . . . . . . . . . . .  10
   6. IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  10
   7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  11
   8. Normative References . . . . . . . . . . . . . . . . . . . . .  11
   9. Informative References . . . . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

















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1. Introduction

   The purpose of the Internet IP Address and AS Number Resource Public
   Key Infrastructure (RPKI) system is to support assertions by current
   resource holders of IP (v4 and v6) address space and AS numbers,
   based on the records of the organizations that act as CAs.  IP
   address and AS number resource information is carried in X.509
   certificates via RFC 3779 extensions [I-D.sidr-res-certs].  Other
   information assertions about resources are expressed via digitally
   signed, non-X.509 data structures that are referred to as "signed
   objects" in the RPKI context [I-D.sidr-arch].  This document
   standardizes a template for specifying signed objects that can be
   validated using the RPKI.

   RPKI signed objects make use of Cryptographic Message Syntax (CMS)
   [RFC5652] as a standard encapsulation format.  CMS was chosen to take
   advantage of existing open source software available for processing
   messages in this format.  RPKI signed objects adhere to a profile
   (specified in Section 2) of the CMS signed-data object.

   The template defined in this document for RPKI signed objects is not
   a complete specification for any particular type of signed object,
   and instead includes only the items which are common to all RPKI
   signed objects. That is, fully specifying a particular type of signed
   object requires an additional document that specifies the details
   which are specific to a particular type of signed object (such as
   ASN.1 syntax for the object's payload and any additional steps
   required to validate the particular type of signed object). Section 4
   describes in more detail the additional pieces that must be specified
   in order to define a new type of RPKI signed object that uses this
   template. Additionally, see [draft-ietf-sidr-roa-format] for an
   example of a document that uses this template to specify a particular
   type of signed object, the Route Origination Authorization.

1.1. Terminology

   It is assumed that the reader is familiar with the terms and concepts
   described in "Internet X.509 Public Key Infrastructure Certificate
   and Certificate Revocation List (CRL) Profile" [RFC5280] and "X.509
   Extensions for IP Addresses and AS Identifiers" [RFC3779].

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119.

1.2. Note on Algorithms

   Cryptographic Message Syntax is a general format capable of



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   accommodating a wide variety of signature and digest algorithms.  The
   algorithms used in the RPKI (and associated key sizes) are specified
   in [I-D.sidr-rpki-algs].

2. Signed Object Syntax

   The RPKI signed object is a profile of the Cryptographic Message
   Syntax (CMS) [RFC5652] signed-data object.  The general format of a
   CMS object is:

      ContentInfo ::= SEQUENCE {
        contentType ContentType,
        content [0] EXPLICIT ANY DEFINED BY contentType }

      ContentType ::= OBJECT IDENTIFIER

   The ContentType is the signed-data type of id-data, namely the id-
   signedData OID, 1.2.840.113549.1.7.2. [RFC5652]

2.1. Signed-Data Content Type

   According to the CMS standard, the signed-data content type is the
   ASN.1 type SignedData:

      SignedData ::= SEQUENCE {
        version CMSVersion,
        digestAlgorithms DigestAlgorithmIdentifiers,
        encapContentInfo EncapsulatedContentInfo,
        certificates [0] IMPLICIT CertificateSet OPTIONAL,
        crls [1] IMPLICIT RevocationInfoChoices OPTIONAL,
        signerInfos SignerInfos }

      DigestAlgorithmIdentifiers ::= SET OF DigestAlgorithmIdentifier

      SignerInfos ::= SET OF SignerInfo

   Additionally, the SignerInfos set must contain only a single
   SignerInfo object.

2.1.1. version

   The version is the syntax version number.  It MUST be 3,
   corresponding to the signerInfo structure having version number 3.

2.1.2. digestAlgorithms

   The digestAlgorithms set contains the OIDs of the digest algorithm(s)
   used in signing the encapsulated content. This set MUST contain



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   exactly one digest algorithm OID, and the OID MUST be selected from
   those specified in [I-D.sidr-rpki-algs].

2.1.3. encapContentInfo

   encapContentInfo is the signed content, consisting of a content type
   identifier and the content itself.  The encapContentInfo represents
   the payload of the RPKI signed object.

        EncapsulatedContentInfo ::= SEQUENCE {
          eContentType ContentType,
          eContent [0] EXPLICIT OCTET STRING OPTIONAL }

        ContentType ::= OBJECT IDENTIFIER

2.1.3.1. eContentType

   This field is left undefined by this profile.  The eContentType is an
   OID specifying the type of payload in this signed object and MUST be
   specified by the document that defines the object.

2.1.3.2. eContent

   This field is left partially undefined by this profile.  The eContent
   is the payload of the signed object and MUST be specified by the
   document that defines the RPKI object.

   At the outermost level, the eContent field MUST be an ASN.1 SEQUENCE.
   The first element of the sequence MUST be the version number, in
   order to enable transition to new versions of signed objects over
   time.

        ContentTemplate ::= SEQUENCE {
          version [0] INTEGER DEFAULT 0,
          ... }

   The document that defines the specific RPKI object MUST specify the
   remaining fields, represented as ellipses (...).

2.1.4. certificates

   The certificates field MUST be included, and MUST contain exactly one
   certificate, RPKI EE certificate needed to validate this signed
   object.

2.1.5. crls

   The crls field MUST be omitted.



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2.1.6. signerInfos

   SignerInfo is defined under CMS as:

         SignerInfo ::= SEQUENCE {
           version CMSVersion,
           sid SignerIdentifier,
           digestAlgorithm DigestAlgorithmIdentifier,
           signedAttrs [0] IMPLICIT SignedAttributes OPTIONAL,
           signatureAlgorithm SignatureAlgorithmIdentifier,
           signature SignatureValue,
           unsignedAttrs [1] IMPLICIT UnsignedAttributes OPTIONAL }

2.1.6.1. version

   The version number MUST be 3, corresponding with the choice of
   SubjectKeyIdentifier for the sid.

2.1.6.2. sid

   The sid is defined as:

         SignerIdentifier ::= CHOICE {
           issuerAndSerialNumber IssuerAndSerialNumber,
           subjectKeyIdentifier [0] SubjectKeyIdentifier }

   For RPKI signed objects, the sid MUST be the SubjectKeyIdentifier
   that appears in the EE certificate carried in the CMS certificates
   field.

2.1.6.3. digestAlgorithm

   The digestAlgorithm MUST consist of the OID of a digest algorithm
   that conforms to the RPKI Algorithms and Key Size Profile
   specification [I-D.sidr-rpki-algs].

2.1.6.4. signedAttrs

   The signedAttrs is defined as:

         SignedAttributes ::= SET SIZE (1..MAX) OF Attribute

         Attribute ::= SEQUENCE {
           attrType OBJECT IDENTIFIER,
           attrValues SET OF AttributeValue }

         AttributeValue ::= ANY




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   The signedAttr element MUST be present and MUST include the content-
   type and message-digest attributes.  The signer MAY also include the
   signing-time signed attribute, the binary-signing-time signed
   attribute, or both signing-time attributes.  Other signed attributes
   MUST NOT be included.

   The signedAttr MUST include only a single instance of any particular
   attribute.  Additionally, even though the syntax allows for a SET OF
   AttributeValue, in an RPKI signed object the attrValues MUST consist
   of only a single AttributeValue.

2.1.6.4.1. Content-Type Attribute

   The ContentType attribute MUST be present.  The attrType OID for the
   ContentType attribute is 1.2.840.113549.1.9.3.

   The attrValues for the ContentType attribute MUST match the
   eContentType in the EncapsulatedContentInfo.  Thus, attrValues must
   contain the OID that specifies the payload type of the specific RPKI
   signed object carried in the CMS signed data structure.

2.1.6.4.2. Message-Digest Attribute

   The MessageDigest Attribute MUST be present.  The attrType OID for
   the MessageDigest Attribute is 1.2.840.113549.1.9.4.

   The attrValues for the MessageDigest attribute contains the output of
   the digest algorithm applied to the content being signed, as
   specified in Section 11.1 of [RFC5652].

2.1.6.4.3. SigningTime Attribute

   The SigningTime Attribute MAY be present. Note that the presence or
   absence of the SigningTime attribute MUST NOT affect the validity of
   the signed object (as specified in Section 3). The attrType OID for
   the SigningTime attribute is 1.2.840.113549.1.9.5.

         id-signingTime OBJECT IDENTIFIER ::= { iso(1) member-body(2)
             us(840) rsadsi(113549) pkcs(1) pkcs9(9) 5 }

   The attrValues for the SigningTime attribute is defined as:

         SigningTime ::= Time

         Time ::= CHOICE {
           utcTime UTCTime,
           generalizedTime GeneralizedTime }




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   The Time element specifies the time, based on the local system clock,
   at which the digital signature was applied to the content.

   The definition of Time matches the one specified in the 1997 version
   of X.509. Additional information regarding the use of UTCTime and
   GeneralizedTime can be found in [RFC5652].

2.1.6.4.4. BinarySigningTime Attribute

   The BinarySigningTime Attribute MAY be present. Note that the
   presence or absence of the BinarySigningTime attribute in no way
   affects the validity of the signed object (as specified in Section
   3). The attrType OID for the SigningTime attribute is
   1.2.840.113549.1.9.16.2.46.

         id-aa-binarySigningTime OBJECT IDENTIFIER ::= { iso(1)
             member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
             smime(16) aa(2) 46 }

   The attrValues for the SigningTime attribute is defined as:

         BinarySigningTime ::= BinaryTime

         BinaryTime ::= INTEGER (0..MAX)

   The BinaryTime element specifies the time, based on the local system
   clock, at which the digital signature was applied to the content. The
   precise definition of the BinaryTime element can be found in
   [RFC4049].

2.1.6.5. signatureAlgorithm

   The signatureAlgorithm MUST conform to the RPKI Algorithms and Key
   Size Profile specification [I-D.sidr-rpki-algs].

2.1.6.6. signature

   The signature value is defined as:

         SignatureValue ::= OCTET STRING

   The signature characteristics are defined by the digest and signature
   algorithms.

2.1.6.7. unsignedAttrs

   unsignedAttrs MUST be omitted.




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3. Signed Object Validation

   Before a relying party can use a signed object, the relying party
   MUST validate the signed object by verifying that all of the
   following conditions hold.  A relying party may perform these checks
   in any order.  Note that these checks are necessary but not
   sufficient: in general, further validation MUST be performed based on
   the specific type of signed object.

   1.  The signed object syntax complies with this specification. In
       particular, that each of the following is true:

       a.  The contentType of the CMS object is SignedData (OID
           1.2.840.113549.1.7.2)

       b.  The version of the SignedData object is 3.

       c.  The certificates field in the SignedData object is present
           and contains one EE certificate, the Subject Key Identifier
           (SKI) field of which matches the sid field of the SignerInfo
           object.

       d.  The crls field in the SignedData object is omitted.

       e.  The version of the SignerInfo is 3.

       f.  The signedAttrs field in the SignerInfo object is present and
           contains both the ContentType attribute (OID
           1.2.840.113549.1.9.3) and the MessageDigest attribute (OID
           1.2.840.113549.1.9.4).

       g.  The eContentType in the EncapsulatedContentInfo is an OID
           that matches the attrValues in the ContentType attribute.

       h.  The unsignedAttrs field in the SignerInfo object is omitted.

       i.  The digestAlgorithm in the SignedData and SignerInfo objects
           conforms to the RPKI Algorithms and Key Size Profile
           specification [I-D.sidr-rpki-algs].

       j.  The signatureAlgorithm in the SignerInfo object conforms to
           the RPKI Algorithms and Key Size Profile specification
           [I-D.sidr-rpki-algs].

   2.  The public key of the EE certificate (contained within the CMS
       signed-data object) can be used to successfully verify the
       signature on the signed object.




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   3.  The EE certificate (contained within the CMS signed-data object)
       is a valid end-entity certificate in the resource PKI as
       specified by [I-D.sidr-res-certs].  In particular, there exists a
       valid certification path from a trust anchor to this EE
       certificate.

   If the above procedure indicates that the signed object is invalid,
   then the signed object MUST be discarded and treated as though no
   signed object were present.  If the all of the conditions above are
   true, then the signed object may be valid.  The relying party MUST
   then perform any additional validation steps required for the
   particular type of signed object.

4. Definition of Specific Signed Objects

   Each RPKI signed object MUST be defined based on this profile, by
   specifying the following data elements and validation procedure:

   1.  eContentType:  Obtain an OID to be used for the eContentType
       field in encapContentInfo.  This OID uniquely identifies the type
       of signed object.

   2.  eContent:  Define an ASN.1 syntax for the eContent field in
       encapContentInfo. The syntax must consist of an ASN.1 SEQUENCE
       whose first element is "version" expressed as an ASN.1 INTEGER.

   3.  Content-Type Attribute:  The mandatory Content-Type Attribute
       must have its attrValues field set to the same OID as
       eContentType in item 1.

   4.  Additional Validation:  Define a set of additional validation
       steps for the specific signed object. Before using this specific
       signed object, a relying party MUST perform both the generic
       validation steps in Section 3 above, as well as these additional
       steps.

5. Security Considerations

       There is no assumption of confidentiality for the data in an RPKI
       signed object.  The integrity and authenticity of each signed
       object is based on the verification of a digital signature for
       the object, and on the validation of the EE certificate used to
       perform that verification.  It is anticipated that signed objects
       will be stored in repositories that will be publicly accessible.

6. IANA Considerations

       None.



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7. Acknowledgements

       The authors wish to thank Charles Gardiner, Russ Housley, and
       Derek Kong for their help and contributions.  Additionally, the
       authors would like to thank Rob Austein, Roque Gagliano, Danny
       McPherson and Sam Weiler for their careful reviews and helpful
       comments.

8. Normative References

   [I-D.sidr-arch] Lepinski, M. and S. Kent, "An Infrastructure to
              Support Secure Internet Routing",
              draft-ietf-sidr-arch-09.txt (work in progress), October
              2009.

   [I-D.sidr-res-certs] Huston, G., Michaleson, G., and R. Loomans, "A
              Profile for X.509 PKIX Resource Certificates",
              draft-ietf-sidr-res-certs-18.txt (work in progress), May
              2010.

   [I-D.sidr-rpki-algs] Huston, G., "A Profile for Algorithms and Key
              Sizes for use in the Resource Public Key Infrastructure",
              draft-huston-sidr-rpki-algs-00.txt (work in progress),
              July 2009.

   [RFC3779]  Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP
              Addresses and AS Identifiers", RFC 3779, June 2004.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, May 2008.

   [RFC5652]  Housley, R., "Cryptographic Message Syntax (CMS)", RFC
              5652, September 2009.

9. Informative References

   [RFC4049]  Housley, R., "BinaryTime: An Alternate Format for
              Representing Date and Time in ASN.1", RFC 4049, April
              2005.

Authors' Addresses

   Matt Lepinski
   BBN Technologies
   10 Moulton Street
   Cambridge MA 02138



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   Email: mlepinski@bbn.com

   Andrew Chi
   BBN Technologies
   10 Moulton Street
   Cambridge MA 02138

   Email: achi@bbn.com

   Stephen Kent
   BBN Technologies
   10 Moulton Street
   Cambridge MA 02138

   Email: kent@bbn.com




































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