Secure Inter-Domain Routing (sidr)                          M. Lepinski
Internet Draft                                                  S. Kent
Expires: November 9, 2011                                       D. Kong
Intended Status: Proposed Standard                     BBN Technologies
                                                            May 9, 2011
                                      
             A Profile for Route Origin Authorizations (ROAs) 
                     draft-ietf-sidr-roa-format-12.txt 


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Abstract 

   This document defines a standard profile for Route Origin 
   Authorizations (ROAs).  A ROA is a digitally signed object that 
   provides a means of verifying that an IP address block holder has 
   authorized an Autonomous System (AS) to originate routes to one or 
   more prefixes within the address block.  

Table of Contents 

    
   1. Introduction...................................................2 
      1.1. Terminology...............................................3 
   2. The ROA ContentType............................................3 
   3. The ROA eContent...............................................3 
      3.1. version...................................................4 
      3.2. asID......................................................4 
      3.3. ipAddrBlocks..............................................4 
   4. ROA Validation.................................................5 
   5. Security Considerations........................................5 
   6. IANA Considerations............................................6 
   7. Acknowledgments................................................6 
   8. References.....................................................7 
      8.1. Normative References......................................7 
      8.2. Informative References....................................7 
   APPENDIX A: ASN.1 Module..........................................8 
   Authors' Addresses................................................9 
    
1. Introduction 

   The primary purpose of the Internet IP Address and Autonomous System 
   (AS) Number Resource Public Key Infrastructure (RPKI) system is to 
   improve routing security. (See [ARCH] for more information.) As part 
   of this system, a mechanism is needed to allow entities to verify 
   that an AS has been given permission by an IP address block holder to 
   advertise routes to one or more prefixes within that block.  A ROA 
   provides this function. 

   The ROA makes use of the template for RPKI digitally signed objects 
   [SIGNOBJ], which defines a Crytopgraphic Message Syntax (CMS) 
   [RFC5652] wrapper for the ROA content as well as a generic validation 
   procedure for RPKI signed objects. Therefore, to complete the 
   specification of the ROA (see Section 4 of [SIGNOBJ]), this document 
   defines: 

 
 
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      1. The OID that identifies the signed object as being a ROA. (This 
         OID appears within the eContentType in the encapContentInfo 
         object as well as the ContentType signed attribute in the 
         signerInfo object.) 

      2. The ASN.1 syntax for the ROA eContent. (This is the payload 
         that specifies the AS being authorized to originate routes as 
         well as the prefixes to which the AS may originate routes.) 

      3. An additional step required to validate ROAs (in addition to 
         the validation steps specified in [SIGNOBJ]).  

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].  

   Additionally, this document makes use of the RPKI signed object 
   profile [SIGNOBJ] and thus familiarity with that document is assumed. 
   Note that the RPKI signed object profile makes use of certificates 
   adhering to the RPKI resource certificate profile [RESCERT] and thus 
   familiarly with this profile is also assumed.  

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 
   "OPTIONAL" in this document are to be interpreted as described in 
   RFC-2119 [RFC2119]. 

    
2. The ROA ContentType 

   The ContentType for a ROA is defined as routeOriginAuthz and has the 
   numerical value of 1.2.840.113549.1.9.16.1.24. 

   This OID MUST appear both within the eContentType in the 
   encapContentInfo object as well as the ContentType signed attribute 
   in the signerInfo object (see [SIGNOBJ]). 

3. The ROA eContent 

   The content of a ROA identifies a single AS that has been authorized 
   by the address space holder to originate routes and a list of one or 
   more IP address prefixes that will be advertised.  If the address 
   space holder needs to authorize multiple ASes to advertise the same 

 
 
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   set of address prefixes, the holder issues multiple ROAs, one per AS 
   number. A ROA is formally defined as: 

      RouteOriginAttestation ::= SEQUENCE { 
         version [0] INTEGER DEFAULT 0, 
         asID  ASID, 
         ipAddrBlocks SEQUENCE (SIZE(1..MAX)) OF ROAIPAddressFamily } 
     
      ASID ::= INTEGER 
       
      ROAIPAddressFamily ::= SEQUENCE { 
         addressFamily OCTET STRING (SIZE (2..3)), 
         addresses SEQUENCE (SIZE (1..MAX)) OF ROAIPAddress } 

    
      ROAIPAddress ::= SEQUENCE { 
         address IPAddress, 
         maxLength INTEGER OPTIONAL } 
    
      IPAddress ::= BIT STRING 

   Note that this content appears as the eContent within the 
   encapContentInfo (see [SIGNOBJ]). 

3.1. version 

   The version number of the RouteOriginAttestation MUST be 0. 

3.2. asID 

   The asID field contains the AS number that is authorized to originate 
   routes to the given IP address prefixes. 

3.3. ipAddrBlocks 

   The ipAddrBlocks field encodes the set of IP address prefixes to 
   which the AS is authorized to originate routes. Note that the syntax 
   here is more restrictive than that used in the IP Address Delegation 
   extension defined in RFC 3779. That extension can represent arbitrary 
   address ranges, whereas ROAs need to represent only prefixes. 

   Within the ROAIPAddressFamily structure, addressFamily contains the 
   Address Family Identifier (AFI) of an IP address family. This 
   specification only supports IPv4 and IPv6. Therefore, addressFamily 
   MUST be either 0001 or 0002.  


 
 
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   Within a ROAIPAddress structure, the addresses field represents 
   prefixes as a sequence of type IPAddress. (See [RFC3779] for more 
   details). If present, the maxLength MUST be an integer greater than 
   or equal to the length of the accompanying prefix and less than or 
   equal to the length (in bits) of an IP address in the address family 
   (32 for IPv4 and 128 for IPv6). When present, the maxLength specifies 
   the maximum length of IP address prefix that the AS is authorized to 
   advertise. (For example, if the IP Address prefix is 203.0.113/24 and 
   the maxLength is 26, the AS is authorized to advertise any more 
   specific prefix having length at most 26. That is, in this example, 
   the AS would be authorized to advertise 203.0.113/24, 
   203.0.113.128/25, or 203.0.113.0/25, but not 203.0.113.0/27.) When 
   the maxLength is not present, the AS is only authorized to advertise 
   exactly the prefix specified in the ROA. 

   Note that a valid ROA may contain an IP Address prefix (within a 
   ROAIPAddress element) that is encompassed by another IP Address 
   prefix (within a separate ROAIPAddress element). For example, a ROA 
   may contain the prefix 203.0.113/24 with maxLength 26, as well as the 
   prefix 203.0.113.0/28 with maxLength 28. (Such a ROA would authorize 
   the indicated AS to advertise any prefix beginning with 203.0.113 
   with length at least 24 and no greater than 26, as well as the 
   specific prefix 203.0.113.0/28.) Additionally, a ROA MAY contain two 
   ROAIPAddress elements where the IP Address prefix is identical in 
   both cases. However, this is NOT RECOMMENDED as in such a case the 
   ROAIPAddress with the shorter maxLength grants no additional 
   privileges to the indicated AS and thus can be omitted without 
   changing the meaning of the ROA. 

4. ROA Validation 

   Before a relying party can use a ROA to validate a routing 
   announcement, the relying party MUST first validate the ROA. To 
   validate a ROA the relying party MUST perform all the validation 
   checks specified in [SIGNOBJ] as well as the following additional 
   ROA-specific validation step. 

   o  The IP Address Delegation extension [RFC3779] is present in the 
      End-Entity (EE) certificate (contained within the ROA) and each IP 
      address prefix(es) in ROA is contained within the set of IP 
      addresses specified by the EE certificate's IP address delegation 
      extension.   

5. Security Considerations 

   There is no assumption of confidentiality for the data in a ROA; it 
   is anticipated that ROAs will be stored in repositories that are 
 
 
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   accessible to all ISPs, and perhaps to all Internet users. There is 
   no explicit authentication associated with a ROA, since the PKI used 
   for ROA validation provides authorization but not authentication. 
   Although the ROA is a signed, application layer object, there is no 
   intent to convey non-repudiation via a ROA.  
    
   The purpose of a ROA is to convey authorization for an AS to 
   originate a route to the prefix(es) in the ROA. Thus the integrity of 
   a ROA MUST be established. The ROA specification makes use of the 
   RPKI signed object format, thus all security considerations in 
   [SIGNOBJ] also apply to ROAs. Additionally, the signed object profile 
   uses the CMS signed message format for integrity, and thus ROA 
   inherit all security considerations associated with that data 
   structure.  

   The right of the ROA signer to authorize the target AS to originate 
   routes to the prefix(es) is established through use of the address 
   space and AS number PKI described in [ARCH]. Specifically one MUST 
   verify the signature on the ROA using an X.509 certificate issued 
   under this PKI, and check that the prefix(es) in the ROA match those 
   in the address space extension in the certificate.  

6. IANA Considerations 

   None. 

7. Acknowledgments 

   The authors wish to thank Charles Gardiner and Russ Housley 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. 















 
 
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8. References 

8.1. Normative References 

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 
             Requirement Levels", BCP 14, RFC 2119, March 1997. 

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

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

   [RFC5280] Cooper, D., et. al., "Internet X.509 Public Key 
             Infrastructure and Certificate Revocation List (CRL) 
             Profile", RFC 5280, May 2008. 

   [RESCERT] Huston, G., Michaelson, G., and Loomans, R., "A Profile for 
             X.509 PKIX Resource Certificates", draft-ietf-sidr-res-
             certs, November 2010. 

   [SIGNOBJ] Lepinski, M., Chi, A., and Kent, S., "Generic Signed 
             Objects for the Resource Public Key Infrastructure", draft-
             ietf-sidr-signed-object, February 2011. 

    

8.2. Informative References 

   [ARCH]    Lepinski, M. and Kent, S., "An Infrastructure to Support 
             Secure Internet Routing," draft-ietf-sidr-arch, February 
             2011. 















 
 
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APPENDIX A: ASN.1 Module 

   This normative appendix provides an ASN.1 module that specifies the 
   ROA content in ASN.1 syntax. 

   RPKI-ROA { iso(1) member-body(2) us(840) rsadsi(113549)   
      pkcs(1) pkcs9(9) smime(16) mod(0) 61 } 
    
   DEFINITIONS EXPLICIT TAGS ::= 
   BEGIN 
    
   RouteOriginAttestation ::= SEQUENCE { 
      version [0] INTEGER DEFAULT 0, 
      asID  ASID, 
      ipAddrBlocks SEQUENCE (SIZE(1..MAX)) OF ROAIPAddressFamily } 
     
   ASID ::= INTEGER 
       
   ROAIPAddressFamily ::= SEQUENCE { 
      addressFamily OCTET STRING (SIZE (2..3)), 
      addresses SEQUENCE (SIZE (1..MAX)) OF ROAIPAddress } 

   ROAIPAddress ::= SEQUENCE { 
      address IPAddress, 
      maxLength INTEGER OPTIONAL } 
    
   IPAddress ::= BIT STRING 

   END 

    

    










 
 
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Authors' Addresses

   Matt Lepinski
   BBN Technologies
   10 Moulton Street
   Cambridge MA 02138
    
   Email: mlepinski@bbn.com
    
   Stephen Kent
   BBN Technologies
   10 Moulton Street
   Cambridge MA 02138
    
   Email: skent@bbn.com
    
   Derrick Kong
   BBN Technologies
   10 Moulton Street
   Cambridge MA 02138
       
   Email: dkong@bbn.com
 
























 
 
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