--- 1/draft-ietf-hip-cert-09.txt 2011-03-09 12:17:35.000000000 +0100 +++ 2/draft-ietf-hip-cert-10.txt 2011-03-09 12:17:35.000000000 +0100 @@ -1,57 +1,63 @@ Host Identity Protocol Heer -Internet-Draft Distributed Systems Group, RWTH -Intended status: Experimental Aachen University -Expires: July 22, 2011 Varjonen - Helsinki Institute for Information +Internet-Draft Communication and Distributed +Updates: 5201 (if approved) Systems, RWTH Aachen University +Intended status: Experimental Varjonen +Expires: September 10, 2011 Helsinki Institute for Information Technology - January 18, 2011 + March 9, 2011 Host Identity Protocol Certificates - draft-ietf-hip-cert-09 + draft-ietf-hip-cert-10 Abstract - The CERT parameter is a container for X.509.v3 certificates and - Simple Public Key Infrastructure (SPKI) certificates. It is used for - carrying these certificates in Host Identity Protocol (HIP) control - packets. This document specifies the certificate parameter and the - error signaling in case of a failed verification. Additionally, this - document specifies the representations of Host Identity Tags in - X.509.v3 and SPKI certificates. + The CERT parameter is a container for digital certificates. It is + used for carrying these certificates in Host Identity Protocol (HIP) + control packets. This document specifies the certificate parameter + and the error signaling in case of a failed verification. + Additionally, this document specifies the representations of Host + Identity Tags in X.509.v3 and SPKI certificates. The concrete use of certificates including how certificates are obtained, requested, and which actions are taken upon successful or failed verification are specific to the scenario in which the certificates are used. Hence, the definition of these scenario- specific aspects are left to the documents that use the CERT parameter. Status of this Memo - This Internet-Draft is submitted in full conformance with the + This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering - Task Force (IETF). Note that other groups may also distribute - working documents as Internet-Drafts. The list of current Internet- - Drafts is at http://datatracker.ietf.org/drafts/current/. + 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." - This Internet-Draft will expire on July 22, 2011. + 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 September 10, 2011. Copyright Notice + Copyright (c) 2011 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 to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of @@ -49,83 +55,82 @@ 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 to this document. Code Components extracted from this document must 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. + described in the BSD License. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. 1. Introduction - Digital certificates bind a piece of information to a public key by + Digital certificates bind pieces of information to a public key by means of a digital signature, and thus, enable the holder of a private key to generate cryptographically verifiable statements. The Host Identity Protocol (HIP) [RFC5201] defines a new cryptographic namespace based on asymmetric cryptography. The identity of each host is derived from a public key, allowing hosts to digitally sign data and issue certificates with their private key. This document specifies the CERT parameter, which is used to transmit digital certificates in HIP. It fills the placeholder specified in Section - 5.2 of [RFC5201]. + 5.2 of [RFC5201], and thus, updates [RFC5201]. 1.1. Requirements Language 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 [RFC2119]. 2. CERT Parameter The CERT parameter is a container for certain types of digital - certificates. It MAY either carry SPKI certificates or X.509.v3 certificates. It does not specify any certificate semantics. However, it defines supplementary parameters that help HIP hosts to transmit semantically grouped CERT parameters in a more systematic way. The specific use of the CERT parameter for different use cases is intentionally not discussed in this document because it is specific to a concrete use case. Hence, the use of the CERT parameter will be defined in the documents that use the CERT parameter. - The CERT parameter is covered, when present, by the HIP SIGNATURE - field and is a non-critical parameter. + The CERT parameter is covered and protected, when present, by the HIP + SIGNATURE field and is a non-critical parameter. The CERT parameter can be used in all HIP packets. However, using it - in the I1 packet is not recommended because it can increase the - processing times of I1s, which can be problematic when processing - storms of I1s. Each HIP control packet MAY contain multiple CERT - parameters. These parameters MAY be related or unrelated. Related - certificates are managed in Cert groups. A Cert group specifies a - group of related CERT parameters that SHOULD be interpreted in a - certain order (e.g., for expressing certificate chains). For - grouping CERT parameters, the Cert group and the Cert count field - MUST be set. Ungrouped certificates exhibit a unique Cert group - field and set the Cert count to 1. CERT parameters with the same - Cert group number in the group field indicate a logical grouping. - The Cert count field indicates the number of CERT parameters in the - group. + in the first Initiator (I1) packet is NOT RECOMMENDED because it can + increase the processing times of I1s, which can be problematic when + processing storms of I1s. Each HIP control packet MAY contain + multiple CERT parameters. These parameters MAY be related or + unrelated. Related certificates are managed in Cert groups. A Cert + group specifies a group of related CERT parameters that SHOULD be + interpreted in a certain order (e.g., for expressing certificate + chains). For grouping CERT parameters, the Cert group and the Cert + count field MUST be set. Ungrouped certificates exhibit a unique + Cert group field and set the Cert count to 1. CERT parameters with + the same Cert group number in the group field indicate a logical + grouping. The Cert count field indicates the number of CERT + parameters in the group. CERT parameters that belong to the same Cert group MAY be contained in multiple sequential HIP control packets. This is indicated by a higher Cert count than the amount of CERT parameters with matching Cert group fields in a HIP control packet. The CERT parameters MUST be placed in ascending order, within a HIP control packet, according to their Cert group field. Cert groups MAY only span multiple packets if the Cert group does not fit the packet. A HIP packet MUST NOT contain more than one incomplete Cert group that continues in the next HIP control packet. @@ -152,112 +157,98 @@ Type 768 Length Length in octets, excluding Type, Length, and Padding Cert group Group ID grouping multiple related CERT parameters Cert count Total count of certificates that are sent, possibly in several consecutive HIP control packets. Cert ID The sequence number for this certificate Cert Type Indicates the type of the certificate Padding Any Padding, if necessary, to make the TLV a multiple of 8 bytes. + The certificates MUST use the algorithms defined in [RFC5201] as the + signature and hash algorithms. + The following certificate types are defined: +--------------------------------+-------------+ | Cert format | Type number | +--------------------------------+-------------+ + | Reserved | 0 | | X.509.v3 | 1 | | SPKI | 2 | | Hash and URL of X.509.v3 | 3 | | Hash and URL of SPKI | 4 | | LDAP URL of X.509.v3 | 5 | | LDAP URL of SPKI | 6 | | Distinguished Name of X.509.v3 | 7 | | Distinguished Name of SPKI | 8 | +--------------------------------+-------------+ - The next sections outline the use of HITs in X.509.v3 and in SPKI - certificates. X.509.v3 certificates are defined in [RFC5280]. The - wire format for X.509.v3 is Distinguished Encoding Rules format as - defined in [X.690]. The SPKI and its formats are defined in - [RFC2693]. + The next sections outline the use of Host Identity Tags (HITs) in + X.509.v3 and in Simple Public Key Infrastructure (SPKI) certificates. + X.509.v3 certificates and the handling procedures are defined in + [RFC5280]. The wire format for X.509.v3 is Distinguished Encoding + Rules format as defined in [X.690]. The SPKI, the handling + procedures, and the formats are defined in [RFC2693]. - Hash and URL encodings (3 and 4) are used as defined in [RFC5996] - Section 3.6. Using hash and URL encodings results in smaller HIP - control packets, but requires the receiver to resolve the URL or - check a local cache against the hash. + Hash and Uniform Resource Locator (URL) encodings (3 and 4) are used + as defined in [RFC5996] Section 3.6. Using hash and URL encodings + results in smaller HIP control packets, but requires the receiver to + resolve the URL or check a local cache against the hash. LDAP URL encodings (5 and 6) are used as defined in [RFC4516]. Using LDAP URL encoding results in smaller HIP control packets but requires the receiver to retrieve the certificate or check a local cache against the URL. Distinguished name (DN) encodings (7 and 8) are used as defined in [RFC4514]. Using the DN encoding results in smaller HIP control packets, but requires the receiver to retrieve the certificate or check a local cache against the DN. 3. X.509.v3 Certificate Object and Host Identities - When using X.509.v3 certificates to transmit information related to - HIP hosts, HITs MAY be enclosed within the certificates. HITs can - represent an issuer, a subject, or both. In X.509.v3 HITs are - represented as issuer or subject alternative name extensions as - defined in [RFC5280]. If only the HIT of the host is presented as - either the issuer or the subject the respective HIT MUST be placed - into the respective entity's DN's Common Name (CN) section in a colon - delimited presentation format defined in [RFC5952]. Inclusion of CN - is not necessary if DN contains any other naming information. It is - RECOMMENDED to use the FQDN/NAI from the hosts HOST_ID parameter in - the DN if one exists. The full HIs are presented in the public key - entries of X.509.v3 certificates. + HITs can represent an issuer, a subject, or both in x.509.v3. HITs + are represented as IPv6 addresses as defined in [RFC4843]. When Host + Identifier ( HI ) is used to sign the certificate the respective HIT + MUST be placed in to the Issuer Alternative Name (IAN) extension + using the GeneralName form iPAddress as defined in [RFC5280]. When + the certificate is issued for a HIP host, identified by a HIT and HI, + the respective HIT MUST be placed in to the Subject Alternative Name + (SAN) extension using the GeneralName form iPAddress and the full HI + is presented as the subjects public key info as defined in [RFC5280]. The following examples illustrate how HITs are presented as issuer - and subject in the DN and in the X.509.v3 extension alternative - names. - - Format of DN: - Issuer: CN=hit-of-issuer - Subject: CN=hit-of-subject - - Example DN: - Issuer: CN=2001:14:6cf:fae7:bb79:bf78:7d64:c056 - Subject: CN=2001:1c:5a14:26de:a07c:385b:de35:60e3 + and subject in the X.509.v3 extension alternative names. Format of X509v3 extensions: X509v3 Issuer Alternative Name: IP Address:hit-of-issuer X509v3 Subject Alternative Name: IP Address:hit-of-subject Example X509v3 extensions: X509v3 Issuer Alternative Name: IP Address:2001:14:6cf:fae7:bb79:bf78:7d64:c056 X509v3 Subject Alternative Name: IP Address:2001:1C:5a14:26de:a07C:385b:de35:60e3 Appendix B shows a full example X.509.v3 certificate with HIP content. - As another example, consider a managed PKI environment in which the - peers have certificates that are anchored in (potentially different) - managed trust chains. In this scenario, the certificates issued to - HIP hosts are signed by intermediate Certificate Authorities (CAs) up - to a root CA. In this example, the managed PKI environment is - neither HIP aware, nor can it be configured to compute HITs and - include them in the certificates. - - In this scenario, it is RECOMMENDED that the HIP peers have and use - some mechanism of defining trusted root CAs for the purpose of - establishing HIP communications. Furthermore it is recommended that - the HIP peers have and use some mechanism of checking peer - certificate validity for revocation, signature, minimum cryptographic - strength, etc., up to the trusted root CA. + As another example, consider a managed Public Key Infrastructure + (PKI) environment in which the peers have certificates that are + anchored in (potentially different) managed trust chains. In this + scenario, the certificates issued to HIP hosts are signed by + intermediate Certificate Authorities (CAs) up to a root CA. In this + example, the managed PKI environment is neither HIP aware, nor can it + be configured to compute HITs and include them in the certificates. When HIP communications are established, the HIP hosts not only need to send their identity certificates (or pointers to their certificates), but also the chain of intermediate CAs (or pointers to the CAs) up to the root CA, or to a CA that is trusted by the remote peer. This chain of certificates MUST be sent in a Cert group as specified in Section 2. The HIP peers validate each other's certificates and compute peer HITs based on the certificate public keys. @@ -315,83 +307,87 @@ 7. IANA Considerations This document defines the CERT parameter for the Host Identity Protocol [RFC5201]. This parameter is defined in Section 2 with type 768. The parameter type number is also defined in [RFC5201]. The CERT parameter has 8-bit unsigned integer field for different certificate types, for which IANA is to create and maintain a new sub-registry entitled "HIP certificate types" under the "Host Identity Protocol (HIP) Parameters". Initial values for the - Certificate type registry are given in Section 2. + Certificate type registry are given in Section 2. New values for the + Certificate types from the unassigned space are assigned through IETF + Review. In Section 6 this document defines two new types for "NOTIFY message types" sub-registry under "Host Identity Protocol (HIP) Parameters". 8. Security Considerations Certificate grouping allows the certificates to be sent in multiple consecutive packets. This might allow similar attacks as IP-layer fragmentation allows, for example sending of fragments in wrong order and skipping some fragments to delay or stall packet processing by the victim in order to use resources (e.g. CPU or memory). Hence, hosts SHOULD implement mechanisms to discard certificate groups with outstanding certificates if state space is scarce. + Checking of the URL and LDAP entries might allow DoS attacks, where + the target host may be subjected to bogus work. + + Security considerations for SPKI certificates are discussed in + [RFC2693] and for X.509.v3 in [RFC5280] + 9. Acknowledgements The authors would like to thank A. Keranen, D. Mattes, M. Komu and T. Henderson for the fruitful conversations on the subject. D. Mattes most notably contributed the non-HIP aware use case in Section 3. -10. References - -10.1. Normative References +10. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2693] Ellison, C., Frantz, B., Lampson, B., Rivest, R., Thomas, B., and T. Ylonen, "SPKI Certificate Theory", RFC 2693, September 1999. [RFC4514] Zeilenga, K., "Lightweight Directory Access Protocol (LDAP): String Representation of Distinguished Names", RFC 4514, June 2006. [RFC4516] Smith, M. and T. Howes, "Lightweight Directory Access Protocol (LDAP): Uniform Resource Locator", RFC 4516, June 2006. + [RFC4843] Nikander, P., Laganier, J., and F. Dupont, "An IPv6 Prefix + for Overlay Routable Cryptographic Hash Identifiers + (ORCHID)", RFC 4843, April 2007. + [RFC5201] Moskowitz, R., Nikander, P., Jokela, P., and T. Henderson, "Host Identity Protocol", RFC 5201, April 2008. [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. - [RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6 - Address Text Representation", RFC 5952, August 2010. - [RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen, "Internet Key Exchange Protocol Version 2 (IKEv2)", RFC 5996, September 2010. -10.2. Informative References - - [X.690] ITU-T, "Recommendation X.690 Information Technology - - ASN.1 encoding rules: Specification of Basic Encoding - Rules (BER), Canonical Encoding Rules (CER) and - Distinguished Encoding Rules (DER)", July 2002, . + [X.690] ITU-T, "Recommendation X.690 (2002) | ISO/IEC 8825-1:2002, + Information Technology - ASN.1 encoding rules: + Specification of Basic Encoding Rules (BER), Canonical + Encoding Rules (CER) and Distinguished Encoding Rules + (DER)", July 2002. Appendix A. SPKI certificate example This section shows a SPKI certificate with encoded HITs. The example has been indented for readability. (sequence (public_key (rsa-pkcs1-sha1 (e #010001#) @@ -538,30 +534,38 @@ leading zeroes in HITs). Changes from version 07 to 08: o Updated and checked the references. Changes from version 08 to 09: o Fixing boilerplate. + Changes from version 09 to 10: + + o IANA considerations updated based on the IANA review. + + o Updates based on the hip-chairs review. + + o Updates based on the Gen-ART review. + Authors' Addresses Tobias Heer - Distributed Systems Group, RWTH Aachen University + Communication and Distributed Systems, RWTH Aachen University Ahornstrasse 55 Aachen Germany - Phone: +49 241 80 214 36 + Phone: +49 241 80 20 776 Email: heer@cs.rwth-aachen.de - URI: http://ds.cs.rwth-aachen.de/members/heer + URI: http://www.comsys.rwth-aachen.de/team/tobias-heer/ Samu Varjonen Helsinki Institute for Information Technology Gustaf Haellstroemin katu 2b Helsinki Finland Email: samu.varjonen@hiit.fi URI: http://www.hiit.fi