Internet DRAFT - draft-zhang-icnrg-pid-naming-scheme

draft-zhang-icnrg-pid-naming-scheme






ICN Research Group                                              X. Zhang
Internet-Draft                                              R. Ravindran
Intended status: Informational                       Huawei Technologies
Expires: February 21, 2014                                        H. Xie
                                                           Huawei & USTC
                                                                 G. Wang
                                                     Huawei Technologies
                                                         August 20, 2013


      PID: A Generic Naming Schema for Information-centric Network
                 draft-zhang-icnrg-pid-naming-scheme-03

Abstract

   In Information-centric network (ICN), everything is an identifiable
   object or entity with a name, such as a named data chunk, a device,
   or a service end.  Different from host-centric connectivity, ICN
   connects named entities using name-based routing and forwarding.  At
   the same time, network entities, end devices, and applications have
   variant demands to verify the integrity and authenticity of these
   entities through names.  This document proposes a generic naming
   schema called PID, which supports trust provenance, content lookup,
   routing, and inter-domain resolution for ICN.  With PID schema, a
   name consists of three components: principal(s), identifier(s), and
   domain(s).  In this draft, we only illustrate the principle and
   concept of PID and the functional role of each component, and leave
   encoding approaches as implementation options.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
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   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on February 21, 2014.

Copyright Notice




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   Copyright (c) 2013 IETF Trust and the persons identified as the
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Table of Contents

   1.  Design Principles  . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Naming in ICN  . . . . . . . . . . . . . . . . . . . . . .  3
     1.2.  Design Principles for Naming in ICN  . . . . . . . . . . .  4
   2.  PID Naming Schema  . . . . . . . . . . . . . . . . . . . . . .  5
     2.1.  Naming Format  . . . . . . . . . . . . . . . . . . . . . .  5
     2.2.  Routing Names  . . . . . . . . . . . . . . . . . . . . . .  6
     2.3.  Cache Access . . . . . . . . . . . . . . . . . . . . . . .  8
     2.4.  Dynamic Content  Routing . . . . . . . . . . . . . . . . .  9
     2.5.  Towards Generic Naming  Schema . . . . . . . . . . . . . . 10
   3.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
   4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   5.  Conclusions  . . . . . . . . . . . . . . . . . . . . . . . . . 11
   6.  Informative References . . . . . . . . . . . . . . . . . . . . 12
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12





















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1.  Design Principles

1.1.  Naming in ICN

   In ICN design, a name has been required to serve for many purposes:
   ICN requires unique names to identify mutable or immutable content or
   information objects with which applications can send requests; in
   data caching, a name is used to look up and access a data chunk; in
   routing and forwarding, a name is used for reaching an information
   object; for security, a provenance between a name and its content
   required via cryptographic credentials.  We summarize the following
   roles that a name may be desired from different perspectives in ICN:

   o  R1 (unique): A name identifies a content object or network entity
      with uniqueness in some scope (e.g., within a domain or Internet).

   o  R2 (locatable): A name enables interested entities to locate its
      identified content object in a network.  For this purpose, the
      name is either routable to reach the locaton of the object, or
      includes information to derive the routable information of the
      object.

   o  R3 (readable): A name enables a user or application to easily
      indicate the content of an object, even without knowing the
      content itself beforehand or before the content is generated.  For
      this, the name may be required to be human-readable.

   o  R4 (authenticable): A name has strong binding with the content
      object (either its publisher or owner, or the content itself), in
      order to provide content access authentication, to enable a
      receiver to verify its provenance, and to prevent denial-of-
      service attacks in an ICN [ICN-name].

   o  R5 (trustable): A name includes information on how to derive the
      trust of a content object, e.g., by an end user who retrieves the
      content from ICN, which may or may not be from its owner or
      publisher.  The trust can be built on mechanisms different trust
      management infrastructures.

   There are many different naming schemes towards all or subset of the
   above roles.  For example, flat names are used in DONA [1] and NetInf
   [2] for global uniqueness and authentication, but do not provide
   readability, routing, and trust-deriving information.  PSIRP and
   PURSUIT [3] sperate the namespaces for rendezvous and forwarding
   identifiers of a name, and both namespaces are flat.  Standard ways
   to name objects with hash functions have been proposed in [4], where
   a named identifier (ni) schema is used to uniquely specify objects.
   This name schema focuses on the uniqueness and strong binding of



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   content objects and names, but not for routing.  Hierarchical flat
   name is proposed in [5], where nested flat names are used for routing
   purposes.  Hierarchical human-readable names are proposed in CCN and
   NDN [6], but they do not provide authentication and trust-deriving
   information.  A generalized form of name is proposed in [7] to bind
   authentication with content names via digital signatures.

1.2.  Design Principles for Naming in ICN

   We follow several principles for defining a general naming schema in
   ICN.

   o  A naming schema satisfies necessary but not more than necessary
      aforementioned roles: in our view, a single-component name cannot
      satisfy all roles at the same time.

   o  A content name identifies a content object in persistent way, such
      that this name does not change with the mobility and multi-home of
      corresponding content object, device, or host.  A client can
      always use this name to retrieve the content from network and
      verify the binding of the content object and the name.

   o  A naming schema should give certain level of flexibility to
      support different networks, considering variant network
      architectures have been proposed, and in the future multiple
      architectures (or features of these archiectures) and current
      Internet may co-exist.  Ideally, a name can include any form of
      identifier, including flat, hierarchical, and human readable or
      non-readable.  The identifier can be chosen by content owner or
      publisher with the uniqueness within certain domain or within an
      application-specific scope.

   o  A network does not use persistent content name for routing
      directly; instead, a "routing name" (or routable address/location/
      label/tag) is network architecture dependent, which is usually
      routable within the network, such that a network node or client
      can reach the content within it.  Usually, a routing name is the
      real location (or locator) of the content in the network.

   o  Per-domain-based (globally or locally) naming resolution services
      (NRS) should be available, to map a persistent content name to
      routing names or locations within a domain.  While per-domain NRS
      updates the routing labels for a content name, it creates a late-
      binding routing behavior.  We note that a single content name can
      be mapped to multiple routing names.  How to implement name
      resolution service is not included in this draft, e.g., [8]
      provides details of one implementation with content container.




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2.  PID Naming Schema

2.1.  Naming Format

   Based on these principles, we propose a P:I:D (or simply PID) naming
   schema for ICN.  Each name is specified by three components of PID,
   where:

   o  P is the principal to bind the object with the complete name for
      security purpose, towards different relationships, e.g.,
      ownership, administration, or social relations.  P is usually
      constructed by hashing the public key of the principal, or hashing
      the content object itself if it is static.  We call the
      relationship between P and the named content object as "security
      binding".

   o  I is an identifier of the object in variant forms and is referred
      by end user, applications, or other entities.  It can be something
      chosen by the publisher or a network service, or administrative
      authorities.  It can be hierarchical or flat, user-readable or
      non-readable, and usually location-independent.  We call the
      relationship between I and the named content object as
      "application binding".

   o  D is the domain that provides resolution from the identifier (I)
      to the real location(s) of the object by routers.  For persistence
      purpose, D can be in any of the following forms:

      *  The locator of the target object if the locator is persistent;

      *  A resolution service name or location which maps the content
         identifier (I) to its real location, if the resolution service
         name is persistent;

      *  A resolution service name that maps the content identifier (I)
         to another resolution service name or location; that is, A is a
         meta-domain;

      *  Any combinations of above.

      We call the relationship between D and the named content object as
      "network binding".

   For example, D can be the domain name of the publisher's domain
   gateway, service, host that can resolve P:I, or a redirection
   gateway, service or host to preserve name persistence to deal with
   mobility or hosted services.  D is the "fall back" used for name-
   resolution if P:I is not resolvable in the local cache of the



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   requesting domain.  D is usually routable (either globally or
   locally), such that, when an application or network node first
   receives an interest with the content name, it can query a resolution
   service by routing with D and obtain the real location or locator of
   the named object.  In case the resolution service is not static, a
   recursive name resolution may be performed, i.e., D points to a
   static resolution service, which in turn points to a dynamic
   resolution service, which points to the location of the object.  If
   there is no D in a name, then a network node uses I to route to the
   location of the object if I is routable.

   D can be in the same namespace of I, but in general it can be
   different.  For example, in one case, D is the container of a set of
   objects which can locate and resolve objects [9].

   For a published name that is in PID schema, a change of any field in
   P or I or D re-names the object, e.g., the object is re-signed by
   another entity, or its resolution service is changed, e.g., the
   publisher changes the host service of a web page.

   We note that the domain concept in PID schema is more general than
   the administration domain in current Internet architecture.  In PID,
   the relationship between a named object and its domain D is for
   location resolution and routing purpose.  It can be the same as the
   administration domain of the content object, or a 3rd party
   resolution service provider, where the designated domain provides
   resolution service.  In more general way, the domain of a name can
   have social-, admin-, owner-, host- relationships with the named
   object, which implies that the domain provides resolution service to
   locate a content object with its name.  A domain can provide a DNS-
   like service that maps a content identifier to the location of the
   object or the resolution service.  Different from current Internet's
   centralized DNS, a domain-based resolution can be more general with a
   distributed implementation.  Furthermore, the meta-domain of a
   content object can be personal profile, e.g., as in social network
   service, an enterprise directory service, a cloud service provider,
   or a web hosting service.  For example, to support the Example 2 of
   [10], the domain part of the content name can be simply the service
   name or location of the lookup database, which is more persistent
   than the mapping of a content identifier to location.  Note that in
   [10], the lookup database is assumed to be static and already known
   by the network, which we believe is not scalable and flexible enough.

2.2.  Routing Names

   As aforementioned, PID schema differentiates content names and
   routing names, where the former is persistent to specify a content
   object, while the later is location-based for routing purpose.



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   Instead of a very specific format of routing names, PID supports
   variant forms of routable names (or routing labels), e.g., a network
   address or a locator.  For a content name P:I:D, the D resolves P:I
   to one or more routing labels, and an application or network router
   can choose one to reach the content object or more for multicast.  A
   routing label for a content object can be dynamic, and can be changed
   from domain to domain.  For example, a single domain may by default
   set a gateway routing label to all the clients it is serving.  The
   gateway then replaces it with some other labels.  Through this way,
   the routing label can allow policy-based intra/inter-domain routing,
   late binding for mobility, and delay-tolerant content routing.

   With a content name provided by a content requester, the network
   first returns the real location of the named object via resolution
   services specified by the domain information (D) in the name.  This
   location information is then augmented in the head field of a PDU
   (e.g., an interest in CCN).  The network then uses this location
   information to reach the object, retrieve the named content, and
   forward back to the requester.  Resolving the location from name and
   augmenting the PDU can be transparent to applications.

   In general, the resolution process works as follows.  With a content
   name P:I:D, a client forwards a request to a network node (e.g., an
   access router).  If not resolvable in the local cache, the router
   first routes to a naming resolution service (NRS) with D. With the
   input of P:I, the NRS returns the routing name ( or routing label) of
   the content object, e.g., a location or a locator.  We note that the
   format and semantics of a routing name can be domain specific, and
   may be only routable in one domain, e.g., it can be a flat location
   in DHT or a hierarchical node name in a network operator.  Upon
   receiving this, the network node inserts this label in the head of
   the interest packet.  The network then uses this routing label to
   reach the next hop, to retrieve the named content by using P:I at
   each hop, and to forward data back to the requester, e.g., following
   the PITs in CCN [6].  In case the routing name resolved from the NRS
   is another name resolution service named with D', the network node
   sends the request to this revolved NRS with D' in interest head,
   obtains the location of the target object, and then inserts the
   location into interest head to obtain the content object.  This
   process happens recursively until the location of the named object
   can be reached.  With a single name, an NRS may return multiple
   entries of the locations of object.  A network node can use one or
   multiple of them to retrieve the object, according to its local
   policy or configuration.

   In another case, where a separate locator address space is not
   managed, a per-hop forwarding can be adopted, where a content router
   tries to resolve the content name identifier (I or P:I) locally in



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   its cache.  If it is un-resolvable, the router uses I:D or just D to
   route to domain D. In the latter case once the interest reaches D,
   the request I:D can be used to route to location(s) of the content
   object.

   Therefore, logically, a data PDU could be of form <P:I:D, <Routing
   Label>, C, Sign_P(I:D,C), Metadata >, where C is the content payload,
   Sign_P is a signature generated from the private key corresponding to
   P on C and persistent content name, and the metadata includes other
   meta attribute information.  With this hybrid naming approach, PID
   schema achieves the benefits of both pure self-certified names and
   hierarchical names.  Specifically, similar to hierarchical human-
   readable name, the P:I part of the schema can achieve global
   uniqueness and readability (if needed).  With D, the schema achieves
   location persistence without including the real location of the
   content object in its name.  With the P part, the schema can achieve
   strong binding between content object and its name for security and
   data integrity.  Note that trust management is usually built on some
   external mechanism out of the naming schema.

   In a special case, the D of a content name P:I:D could also serve as
   a routing label; That is, D can serve dual purposes: a resolution/
   redirection point, and a routing label as well.  For example, D can
   directly resolve to a container (server).  This avoids one RTT to
   obtain the routing labels of the content name.

   While D can serve the same purpose of routing label that is proposed
   in [10], PID schema has two improvements:

   o  PID has better persistence property since it separates routing
      labels from content names, while in [10], a content ID includes
      both routing labels and identifier.  When the routing label of a
      content object is changed, e.g., the host service is changed, or a
      new host service is added, the content ID has to be changed, which
      breaks the name persistency.

   o  PID has stronger security binding of names and content objectgs
      via principal field.

   Note: We focus on the logical semantics of fields in a naming in this
   document.  In implementation, variant formats of PID can be options.
   For example, I:D can be in a single component, which acts as a
   resolvable identifier.

2.3.  Cache Access

   With a content name of P:I:D, a router can use the full name to index
   and look up cached content chunks and pending interests, e.g., in



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   content sore (CS) and pending interest table (PIT) in [6].
   Optionally, a router can only use P and I for the same purposes.
   This achieves location independence in data storage and forwarding,
   e.g., when a content chunk with P and I can satisfy any request of
   P:I:D with all possible Ds.  That is, two content objects with same P
   and I are considered as the same and thus only one is cached at
   anytime, even though they may have different Ds.

2.4.  Dynamic Content  Routing

   The PID schema lends itself to allow consuming and producing
   applications to choose naming semantic that meets requirements in
   terms of reliability, security, or performance metrics.  The naming
   format follows a P:I:D format, where I identifies the named entity
   with a local or global scope, and D is the authority which could
   resolve the entity's location(s), and P securely binds the content
   object to I. For content routing I:D is the relevant portion.  As I
   could be a hierarchical or flat name, several options for content
   routing are possible.  In one case separate ICN domains can be built
   that are optimized to deal with either flat or hierarchical names,
   where name-resolution service allows the request to be directed to
   the appropriate domain criterion determined by the publisher,
   consumer or based on certain routing policies.  In another case, a
   content routing domain can be built where the name-resolution
   infrastructure is enabled to deal with both flat and hierarchical
   names, where irrespective of the type of naming, a separate locator
   space exists to resolve the content name to its location(s).

   If the combination of I:D is hierarchical, the content routing can
   follow the resolution mechanism similar to CCN.  To resolve an
   interest, either I itself could be routable if it is globally unique,
   or the combination of I:D should be routable, which shall be
   interpretable by the name resolution service handling hierarchical
   names.  Such ICN domains can leverage longest prefix match to take
   advantage of name-prefix aggregation mitigating routing scalability
   issue.

   If I is flat, then the resolution through D should return a routing
   label(s), which can be appended to the interest packet for intra- and
   inter-domain name based routing on a fast path, or the name
   resolution can be handled by the global name resolution
   infrastructure through inter-domain cooperation on a slow path.

   There are several considerations for dynamic name based routing.
   Based on the particular naming constructions, e.g., hierarchical,
   flat, or hybrid, each of which achieves the same objectives
   respectively with different mechanisms.




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2.5.  Towards Generic Naming  Schema

   In a general case, one object may have several names.  Different
   names are assigned by different domains and served for different
   purposes.  Logically, for a single object (e.g., a content object, a
   device, an application, or a service), it can have multiple
   identifiers, For example, a mobile device may have identifiers of an
   IMEI number, a phone number, an IP address, a human readable name
   (e.g., Alice's iPhone), and an organizational device id (e.g., if the
   device belongs to a company).  A user generated content can have a
   user chosen ID, a URL, and a tinyURL.  All these identifiers can have
   a single principal.  Therefore the name of the object can be P:(I1:
   ...:In):D, where Ix is an identifier, D is a domain that provides
   name resolution service, and P is the principal.

   In a very general case, each identifier can be associated with
   different principals, and multiple locators can be used for a single
   content object, e.g., for load balance and duplication purposes.  For
   example, Abel's iPhone has different public keys for different names
   it may use for different network services, one for Abel's personal
   use, and another from his company.  Therefore, the relationship
   between the object, the identifiers, and the principals is a multi-
   element set.

   As one object may have many persistent domains (e.g., a content is
   stored at different host services or CDNs), and one object may also
   have many IDs, in this generic schema, both domain and identifier may
   be a multi-element set, and content routers and consumers can select
   variant elements for content routing and forwarding (based on locally
   defined policy).

   Note that there can be mapping relationships between multiple names
   of a single object.  For example, an object may have a hierarchical
   identifier within its local domain owned by an enterprise, but has a
   flat identifier (hash of its content) with a DHT service.  There can
   be a mapping service to link these two names towards the same object.

   In general, mapping function among different names of a single object
   can be used to build flexible relationships between names, such as:

   o  An identifier can be derived from another identifier, which forms
      nested or tunneled names.

   o  A principal can be signed by another principal, to build trust
      between different principals, such as for ownership,
      administration, and social relationships.





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   o  A domain name can point to another domain name for the same
      object.

   The PID schema can support these levels of flexibility.  However, we
   consider these are extensions of core naming schema.


3.  Security Considerations

   As traditional, the integrity of a content object is maintained by a
   signature included in each data chunk.  If the principal (P) of the
   object name is the public key or hash of the public key of its
   publisher, this key can be used to verify the integrity and
   authenticity of the object.  When P is the hash of the content
   itself, the signature itself is built with P. Therefore, PID provides
   a strong binding between a name and its content object.

   When P is (the hash of) a public key, it can be the trust derivation
   information of the object, e.g., an end user can use it to decide
   whether to trust the content object or not, based on a trust
   management infrastructure such as PKI or name-based trust [11].
   However, PID schema is independent from any trust management
   infrastructure.  The trust of a content object is derived from the
   trust of the principal.  Either a network node or an end user can
   verify the trust of a content object.  The trust management
   infrastructure is out of the scope of PID schema.

   Similar to [6], the public key of a principal can be regular ICN
   data, also with the name format of P:I:D. For the name of a certified
   public key, its I can be some domain- or realm-based name, D can be
   the name (if static) of the certificate directory service of a CA, or
   a domain that resolves the location of a public key certificate, and
   the P is the hash the CA's public key.


4.  IANA Considerations

   This document makes no specific request of IANA.


5.  Conclusions

   In this draft, we propose PID, a naming schema for ICN.  With this
   schema, an object name includes a principal P, an identifier I, and a
   domain D. The principal P acts for security binding, e.g., to verify
   if the object is bounded with its name, and to derive the trust of
   the object with possible trust management mechanisms.  The identifier
   I identifies the object within certain scope, and can be used for



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   application binding such as caching access.  The D refers to a name
   resolution service that can resolve the real time location of the
   object, directly or recursively.  While this draft lays out the basic
   design principles and workflows of PID, we leave its encoding and
   implementation options to other documentations, such as [9].


6.  Informative References

   [1]   I. Koponen et al., "A Data-Oriented (and Beyond) Network
         Architecture.", Proc. of ACM SIGCOMM 2007.

   [2]   C. Dannewitz et al., "Secure Naming for a Network of
         Information.", IEEE INFOCOM Computer Communications
         Workshops 2010.

   [3]   PURSUIT, "http://www.fp7-pursuit.eu".

   [4]   S. Farrell et al., "Naming Things with Hashes.",
         http://datatracker.ietf.org/doc/draft-farrell-decade-ni/ 2012.

   [5]   A. Ghodsi et al., "Naming in Content-Oriented Architectures.",
         Proc. of ACM ICN Workshop 2011.

   [6]   V. Jacobson et al., "Networking named content.", Proc. of ACM
         CoNEXT 2009.

   [7]   D. Smetters and V. Jacobson, "Securing Network Content.", PARC
         Technical Report 2009.

   [8]   R. Wang et al., "Container Resolution System in ICN.", http://
         datatracker.ietf.org/doc/
         draft-wang-icnrg-container-resolution-system/ 2013.

   [9]   C. Yao et al., "Container Assisted Naming and Routing for
         ICN.",  http://www.ietf.org/internet-drafts/
         draft-yao-icnrg-naming-routing-00.txt. 2013.

   [10]  A. Narayanan and D. Oran, "NDN and IP Routing, Can it Scale?",
         http://trac.tools.ietf.org/group/irtf/trac/raw-attachment/wiki/
         icnrg/IRTF%20-%20CCN%20And%20IP%20Routing%20-%202.pdf 2011.

   [11]  X. Zhang et al., "Towards name-based trust and security for
         content-centric network.", Proc. of IEEE ICNP 2011.







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Authors' Addresses

   Xinwen Zhang
   Huawei Technologies
   2330 Central Expressway
   Santa Clara, CA  95050
   USA

   Phone:
   Email: xinwenzhang@gmail.com


   Ravi Ravindran
   Huawei Technologies
   2330 Central Expressway
   Santa Clara, CA  95050
   USA

   Phone:
   Email: ravi.ravindran@huawei.com


   Haiyong Xie
   Huawei & USTC
   2330 Central Expressway
   Santa Clara, CA  95050
   USA

   Phone:
   Email: haiyong.xie@huawei.com


   Guoqiang Wang
   Huawei Technologies
   2330 Central Expressway
   Santa Clara, CA  95050
   USA

   Phone:
   Email: gq.wang@huawei.com











Zhang, et al.           Expires February 21, 2014              [Page 13]