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<rfc docName="draft-ietf-hip-rfc4423-bis-12" category="info" obsoletes="4423" ipr="pre5378Trust200902">
<front>
<title>Host Identity Protocol Architecture</title>
<author initials="R." surname="Moskowitz"
fullname="Robert Moskowitz" role="editor">
<organization abbrev="HTT Consulting">HTT Consulting</organization>
<address>
<postal>
<street>Oak Park</street>
<!-- <city>Oak Park</city> -->
<region>Michigan</region>
<country>USA</country>
</postal>
<email>rgm@labs.htt-consult.com</email>
</address>
</author>
<author initials="M.K.T." surname="Komu"
fullname="Miika Komu">
<organization abbrev="Ericsson">Ericsson
</organization>
<address>
<postal>
<street>Hirsalantie 11</street>
<city>02420 Jorvas</city>
<country>Finland</country>
</postal>
<email>miika.komu@ericsson.com</email>
</address>
</author>
<date month="June" year="2015" />
<area>Internet</area>
<keyword>Request for Comments</keyword>
<keyword>RFC</keyword>
<keyword>Internet Draft</keyword>
<keyword>I-D</keyword>
<abstract>
<t>This memo describes a new namespace, the Host Identity namespace,
and a new protocol layer, the Host Identity Protocol, between the
internetworking and transport layers. Herein are presented the
basics of the current namespaces, their strengths and
weaknesses, and how a new namespace will add completeness to
them. The roles of this new namespace in the protocols are
defined. </t>
<t>
This document obsoletes RFC 4423 and addresses the concerns raised by
the IESG, particularly that of crypto agility. It incorporates
lessons learned from the implementations of RFC 5201 and goes further
to explain how HIP works as a secure signaling channel.
</t>
</abstract>
</front>
<middle>
<section title="Introduction">
<t>The Internet has two important global namespaces: Internet
Protocol (IP) addresses and Domain Name Service (DNS) names.
These two namespaces have a set of features and abstractions
that have powered the Internet to what it is today. They also
have a number of weaknesses. Basically, since they are all we
have, we try and do too much with them. Semantic overloading
and functionality extensions have greatly complicated these
namespaces.</t>
<t>The proposed Host Identity namespace fills an important gap between
the IP and DNS namespaces. A Host Identity conceptually refers
to a computing platform, and there may be multiple such Host
Identities per computing platform (because the platform may wish
to present a different identity to different communicating peers).
The Host Identity namespace consists of Host Identifiers (HI).
There is exactly one Host Identifier for each Host Identity
(although there may be transient periods of time such as key
replacement when more than one identifier may be active).
While this text later talks about non-cryptographic Host Identifiers,
the architecture focuses on the case in which Host Identifiers are
cryptographic in nature. Specifically, the Host Identifier is the
public key of an asymmetric key-pair. Each Host Identity uniquely
identifies a single host, i.e., no two hosts have the same Host
Identity. If two or more computing platforms have the same Host
Identifier, then they are instantiating a distributed host. The Host
Identifier can either be public (e.g. published in the DNS), or
unpublished. Client systems will tend to have both public and
unpublished Host Identifiers.</t>
<t>There is a subtle but important difference between Host
Identities and Host Identifiers. An Identity refers to the
abstract entity that is identified. An Identifier, on the other
hand, refers to the concrete bit pattern that is used in the
identification process.</t>
<t>Although the Host Identifiers could be used in many
authentication systems, such as <xref
target="RFC4306">IKEv2</xref>, the presented
architecture introduces a new protocol, called the Host Identity
Protocol (HIP), and a cryptographic exchange, called the HIP
base exchange; see also <xref target="control-plane"/>.
HIP provides for limited forms of
trust between systems, enhance mobility, multi-homing and
dynamic IP renumbering, aid in protocol translation / transition,
and reduce certain types of denial-of-service (DoS) attacks.
</t>
<t>When HIP is used, the actual payload traffic between two HIP
hosts is typically, but not necessarily, protected with ESP
<xref target="RFC7402" />.
The Host Identities are used to create the needed ESP Security
Associations (SAs) and to authenticate the hosts. When ESP is
used, the actual payload IP packets do not differ in any way
from standard ESP protected IP packets.</t>
<t>
Much has been learned about HIP <xref target="RFC6538" /> since <xref target="RFC4423" />
was published. This document expands Host Identities beyond use
to enable IP connectivity and security to general interhost secure
signalling at any protocol layer. The signal may establish a security
association between the hosts, or simply pass information within
the channel.
</t>
</section>
<section title="Terminology">
<?rfc compact="no"?>
<section title="Terms common to other documents">
<texttable>
<ttcol width="20%" align="left">Term</ttcol>
<ttcol align="left">Explanation</ttcol>
<c>Public key</c><c>The public key of an asymmetric
cryptographic key pair. Used as a publicly known identifier
for cryptographic identity authentication.
Public is a a relative term here, ranging from "known to
peers only" to "known to the world."</c>
<c>Private key</c><c>The private or secret key of an
asymmetric cryptographic key pair. Assumed to be known only
to the party identified by the corresponding public key.
Used by the identified party to authenticate its identity to
other parties.</c>
<c>Public key pair</c><c>An asymmetric cryptographic key
pair consisting of public and private keys. For example,
Rivest-Shamir-Adleman (RSA), Digital Signature Algorithm
(DSA) and Elliptic Curve DSA (ECDSA) key pairs are such key pairs.</c>
<c>End-point</c><c>A communicating entity. For
historical reasons, the term 'computing platform' is used in
this document as a (rough) synonym for end-point.</c>
</texttable>
</section>
<?rfc compact="yes"?>
<?rfc compact="no"?>
<section title="Terms specific to this and other HIP documents">
<t>It should be noted that many of the terms defined herein
are tautologous, self-referential or defined through circular
reference to other terms. This is due to the succinct nature
of the definitions. See the text elsewhere in this document
and the base specification <xref target="RFC7401" /> for more elaborate
explanations.</t>
<texttable>
<ttcol width="20%" align="left">Term</ttcol>
<ttcol align="left">Explanation</ttcol>
<c>Computing platform</c><c>An entity capable of
communicating and computing, for example, a computer. See
the definition of 'End-point', above.</c>
<c>HIP base exchange</c><c>A cryptographic protocol;
see also <xref target="control-plane"/>.</c>
<c>HIP packet</c><c>An IP packet that carries a 'Host
Identity Protocol' message.</c>
<c>Host Identity</c><c>An abstract concept assigned to
a 'computing platform'. See 'Host Identifier', below.</c>
<c>Host Identity namespace</c><c>A name space
formed by all possible Host Identifiers.</c>
<c>Host Identity Protocol</c><c>A protocol used to
carry and authenticate Host Identifiers and other
information. </c>
<c>Host Identity Hash</c><c>The cryptographic hash used
in creating the Host Identity Tag from the Host Identity.</c>
<c>Host Identity Tag</c><c>A 128-bit datum created by
taking a cryptographic hash over a Host Identifier plus
bits to identify which hash used.</c>
<c>Host Identifier</c><c>A public key used as a name
for a Host Identity.</c>
<c>Local Scope Identifier</c><c>A 32-bit datum denoting
a Host Identity.</c>
<c>Public Host Identifier and Identity</c><c>A
published or publicly known Host Identifier used as a public
name for a Host Identity, and the corresponding
Identity.</c>
<c>Unpublished Host Identifier and Identity</c><c>A
Host Identifier that is not placed in any public directory,
and the corresponding Host Identity. Unpublished Host
Identities are typically short lived in nature, being often
replaced and possibly used just once.</c>
<c>Rendezvous Mechanism</c><c>A mechanism used to
locate mobile hosts based on their HIT.</c>
</texttable>
</section>
<?rfc compact="yes"?>
</section>
<section title="Background">
<t>The Internet is built from three principal components:
computing platforms (end-points), packet transport
(i.e., internetworking) infrastructure, and services
(applications). The Internet exists to service two principal
components: people and robotic services (silicon-based people,
if you will). All these components need to be named in order to
interact in a scalable manner. Here we concentrate on naming
computing platforms and packet transport elements.</t>
<t>There are two principal namespaces in use in the Internet for
these components: IP addresses, and Domain Names.
Domain Names provide hierarchically assigned names for some
computing platforms and some services. Each hierarchy is
delegated from the level above; there is no anonymity in Domain
Names. Email, HTTP, and SIP addresses all reference Domain
Names.</t>
<t>The IP addressing namespace has been overloaded to name both
interfaces (at layer-3) and endpoints (for the endpoint-specific
part of layer-3, and for layer-4). In their role as interface
names, IP addresses are sometimes called "locators" and serve
as an endpoint within a routing topology.</t>
<t>IP addresses are numbers that name networking interfaces, and typically only
when the interface is connected to the network. Originally, IP
addresses had long-term significance. Today, the vast number of
interfaces use ephemeral and/or non-unique IP addresses. That is,
every time an interface is connected to the network, it is
assigned an IP address.</t>
<t>In the current Internet, the transport layers are coupled to
the IP addresses. Neither can evolve separately from the other.
IPng deliberations were strongly shaped by the decision that a
corresponding TCPng would not be created.</t>
<t>There are three critical deficiencies with the current
namespaces. Firstly, dynamic readdressing cannot be directly
managed. Secondly, confidentiality is not provided in a consistent,
trustable manner. Finally, authentication for systems and
datagrams is not provided. All of these deficiencies arise
because computing platforms are not well named with the current
namespaces. </t>
<section title="A desire for a namespace for computing platforms">
<t>An independent namespace for computing platforms could be
used in end-to-end operations independent of the evolution of
the internetworking layer and across the many internetworking
layers. This could support rapid readdressing of the
internetworking layer because of mobility, rehoming, or
renumbering.</t>
<t>If the namespace for computing platforms is based on
public-key cryptography, it can also provide authentication
services. If this namespace is locally created without
requiring registration, it can provide anonymity. </t>
<t>Such a namespace (for computing platforms) and the names in
it should have the following characteristics:
<list style="symbols">
<t>The namespace should be applied to the IP 'kernel' or stack.
The IP stack is the 'component' between applications and the
packet transport infrastructure.</t>
<t>The namespace should fully decouple the internetworking
layer from the higher layers. The names should replace
all occurrences of IP addresses within applications (like
in the Transport Control Block, TCB). This replacement can
be handled transparently for legacy applications as the
LSIs and HITs are compatible with IPv4 and IPv6 addresses
<xref target="RFC5338" />. However, HIP-aware applications
require some modifications from the developers, who may
employ networking API extensions for HIP <xref
target="RFC6317" />.</t>
<t>The introduction of the namespace should not mandate
any administrative infrastructure. Deployment must come
from the bottom up, in a pairwise deployment.</t>
<t>The names should have a fixed length representation,
for easy inclusion in datagram headers and existing
programming interfaces (e.g the TCB).</t>
<t>Using the namespace should be affordable when used in
protocols. This is primarily a packet size issue. There
is also a computational concern in affordability.</t>
<t>Name collisions should be avoided as much as possible. The
mathematics of the birthday paradox can be used to estimate
the chance of a collision in a given population and hash space.
In general, for a random hash space of size n bits, we would
expect to obtain a collision after approximately 1.2*sqrt(2**n)
hashes were obtained. For 64 bits, this number is roughly
4 billion. A hash size of 64 bits may be too small to avoid
collisions in a large population; for example, there is a 1%
chance of collision in a population of 640M. For 100 bits
(or more), we would not expect a collision until approximately
2**50 (1 quadrillion) hashes were generated.</t>
<t>The names should have a localized abstraction so that they can be
used in existing protocols and APIs.</t>
<?rfc needLines="8"?>
<t>It must be possible to create names locally. When such names
are not published, this can provide anonymity at the cost of
making resolvability very difficult.
<!--
<list style="symbols">
<t>Sometimes the names may contain a delegation
component. This is the cost of resolvability.</t>
</list>
-->
</t>
<t>The namespace should provide authentication services.</t>
<t>The names should be long lived, but replaceable at any
time. This impacts access control lists; short lifetimes
will tend to result in tedious list maintenance or require
a namespace infrastructure for central control of access
lists.</t>
</list>
</t>
<t>In this document, a new namespace approaching these ideas
is called the Host Identity namespace. Using Host Identities
requires its own protocol layer, the Host Identity Protocol,
between the internetworking and transport layers. The names
are based on public-key cryptography to supply authentication
services. Properly designed, it can deliver all of the above
stated requirements.</t>
</section>
</section>
<section title="Host Identity namespace">
<t>A name in the Host Identity namespace, a Host Identifier
(HI), represents a statistically globally unique name for naming
any system with an IP stack. This identity is normally
associated with, but not limited to, an IP stack. A system can
have multiple identities, some 'well known', some unpublished or
'anonymous'. A system may self-assert its own identity, or may
use a third-party authenticator like DNSSEC <xref
target="RFC2535" />, PGP, or X.509 to 'notarize' the identity
assertion to another namespace. It is expected that the Host Identifiers will
initially be authenticated with DNSSEC and that all
implementations will support DNSSEC as a minimal baseline.</t>
<t>In theory, any name that can claim to be 'statistically
globally unique' may serve as a Host Identifier. In the HIP
architecture, the public key of a private-public key pair has
been chosen as the Host Identifier because it can be self
managed and it is computationally difficult to forge. As
specified in the Host Identity Protocol <xref
target="RFC7401" /> specification, a public-key-based HI can
authenticate the HIP packets and protect them from man-in-the-middle
attacks. Since authenticated datagrams are
mandatory to provide much of HIP's denial-of-service protection,
the Diffie-Hellman exchange in HIP base exchange has to be authenticated.
Thus, only public-key HI and authenticated HIP messages are
supported in practice.</t>
<t>In this document, the non-cryptographic forms of HI and HIP
are presented to complete the theory of HI, but they should not
be implemented as they could produce worse denial-of-service
attacks than the Internet has without Host Identity. There has
been past research in challenge puzzles to use non-cryptographic
HI, for Radio Frequency IDentification (RFID), in an HIP
exchange tailored to the workings of such challenges (as
described further in <xref target="urien-rfid" /> and <xref
target="urien-rfid-draft" />).</t>
<section title="Host Identifiers">
<t>Host Identity adds two main features to Internet protocols.
The first is a decoupling of the internetworking and transport
layers; see <xref target="sec-architecture" />. This
decoupling will allow for independent evolution of the two
layers. Additionally, it can provide end-to-end services over
multiple internetworking realms. The second feature is host
authentication. Because the Host Identifier is a public key,
this key can be used for authentication in security protocols
like ESP.</t>
<t>The only completely defined structure of the Host Identity
is that of a public/private key pair. In this case, the Host
Identity is referred to by its public component, the public
key. Thus, the name representing a Host Identity in the Host
Identity namespace, i.e., the Host Identifier, is the public
key. In a way, the possession of the private key defines the
Identity itself. If the private key is possessed by more than
one node, the Identity can be considered to be a distributed
one.</t>
<t>Architecturally, any other Internet naming convention might
form a usable base for Host Identifiers. However,
non-cryptographic names should only be used in situations of
high trust - low risk. That is any place where host
authentication is not needed (no risk of host spoofing) and no
use of ESP. However, at least for interconnected networks
spanning several operational domains, the set of environments
where the risk of host spoofing allowed by non-cryptographic
Host Identifiers is acceptable is the null set. Hence, the
current HIP documents do not specify how to use any other
types of Host Identifiers but public keys. For instance,
Back-to-My-Mac <xref target="RFC6281" /> from Apple comes
pretty close to the functionality of HIP, but unlike HIP, it
is based on non-cryptographic identifiers.
</t>
<t>The actual Host Identifiers are never directly used at the
transport or network layers. The corresponding Host
Identifiers (public keys) may be stored in various DNS or other
directories as identified elsewhere in this document, and they
are passed in the HIP base exchange. A Host Identity Tag
(HIT) is used in other protocols to represent the Host
Identity. Another representation of the Host Identities, the
Local Scope Identifier (LSI), can also be used in protocols
and APIs.</t>
</section>
<section title="Host Identity Hash (HIH)">
<t>The Host Identity Hash is the cryptographic hash algorithm used in
producing the HIT from the HI. It is also the hash used
throughout the HIP protocol for consistency and simplicity. It
is possible to for the two hosts in the HIP exchange to use
different hash algorithms.</t>
<t>Multiple HIHs within HIP are needed to address the moving
target of creation and eventual compromise of cryptographic
hashes. This significantly complicates HIP and offers an
attacker an additional downgrade attack that is mitigated
in the HIP protocol <xref target="RFC7401" />.</t>
</section>
<section title="Host Identity Tag (HIT)">
<t>A Host Identity Tag is a 128-bit representation for a Host
Identity. It is created from an HIH,
an IPv6 prefix <xref target="RFC7343" /> and a hash identifier. There are two advantages
of using the HIT over using the Host Identifier in protocols.
Firstly, its fixed length makes for easier protocol coding and
also better manages the packet size cost of this technology.
Secondly, it presents the identity in a consistent format to
the protocol independent of the cryptographic algorithms
used.</t>
<t>In essence, the HIT is a hash over the public key. As such,
two algorithms affect the generation of a HIT: the public-key
algorithm of the HI and the used HIH. The two algorithms are
encoded in the bit presentation of the HIT. As the two
communicating parties may support different algorithms, <xref
target="RFC7401" /> defines the minimum set for
interoperability. For further interoperability, the responder
may store its keys in DNS records, and thus the initiator may
have to couple destination HITs with appropriate source HITs
according to matching HIH.</t>
<t>In the HIP packets, the HITs identify the sender and
recipient of a packet. Consequently, a HIT should be unique
in the whole IP universe as long as it is being used. In the
extremely rare case of a single HIT mapping to more than one
Host Identity, the Host Identifiers (public keys) will make
the final difference. If there is more than one public key
for a given node, the HIT acts as a hint for the correct
public key to use.</t>
</section>
<section title="Local Scope Identifier (LSI)" anchor="lsi">
<t>An LSI is a 32-bit localized representation for a Host
Identity. The purpose of an LSI is to facilitate using Host
Identities in existing APIs for IPv4-based
applications. Besides facilitating HIP-based connectivity for
legacy IPv4 applications, the LSIs are beneficial in two other
scenarios <xref target="RFC6538" />.</t>
<t>In the first scenario, two IPv4-only applications are
residing on two separate hosts connected by IPv6-only
network. With HIP-based connectivity, the two applications are
able to communicate despite of the mismatch in the protocol
families of the applications and the underlying network. The
reason is that the HIP layer translates the LSIs originating
from the upper layers into routable IPv6 locators before
delivering the packets on the wire.</t>
<t>The second scenario is the same as the first one, but with
the difference that one of the applications supports only
IPv6. Now two obstacles hinder the communication between the
application: the addressing families of the two applications
differ, and the application residing at the IPv4-only side is
again unable to communicate because of the mismatch between
addressing families of the application (IPv4) and network
(IPv6). With HIP-based connectivity for applications, this
scenario works; the HIP layer can choose whether to translate
the locator of an incoming packet into an LSI or HIT.</t>
<t>Effectively, LSIs improve IPv6 interoperability at the
network layer as described in the first scenario and at the
application layer as depicted in the second example. The
interoperability mechanism should not be used to avoid
transition to IPv6; the authors firmly believe in IPv6
adoption and encourage developers to port existing IPv4-only
applications to use IPv6. However, some proprietary,
closed-source, IPv4-only applications may never see the
daylight of IPv6, and the LSI mechanism is suitable for
extending the lifetime of such applications even in IPv6-only
networks.</t>
<t>The main disadvantage of an LSI is its local
scope. Applications may violate layering principles and pass
LSIs to each other in application-layer protocols. As the LSIs
are valid only in the context of the local host, they may
represent an entirely different host when passed to another
host. However, it should be emphasized here that the LSI
concept is effectively a host-based NAT and does not introduce
any more issues than the prevalent middlebox based NATs for
IPv4. In other words, the applications violating layering
principles are already broken by the NAT boxes that are
ubiquitously deployed.</t>
</section>
<section title="Storing Host Identifiers in directories">
<t>The public Host Identifiers should be stored in DNS; the
unpublished Host Identifiers should not be stored anywhere
(besides the communicating hosts themselves). The (public) HI
along with the supported HIHs are stored in a new RR type. This RR type
is defined in <xref target="I-D.ietf-hip-rfc5205-bis">HIP DNS Extension</xref>.</t>
<t>Alternatively, or in addition to storing Host Identifiers
in the DNS, they may be stored in various other
directories. For instance, a directory based on the
Lightweight Directory Access Protocol (LDAP) or a Public Key
Infrastructure (PKI) <xref target="I-D.ietf-hip-rfc6253-bis" /> may be used.
Alternatively, <xref target="RFC6537">Distributed Hash Tables (DHTs)</xref> have
successfully been utilized <xref target="RFC6538" />. Such a
practice may allow them to be used for purposes other than
pure host identification.</t>
<t>Some types of applications may cache and use Host
Identifiers directly, while others may indirectly discover
them through symbolic host name (such as FQDN) look up from a
directory. Even though Host Identities can have a
substantially longer lifetime associated with them than
routable IP addresses, directories may be a better approach to
manage the lifespan of Host Identities. For example, an LDAP-based directory or DHT
can be used for locally published identities whereas DNS
can be more suitable for public advertisement.</t>
</section>
</section>
<section anchor="sec-architecture" title="New stack architecture">
<t>One way to characterize Host Identity is to compare the
proposed new architecture with the current one.
<!-- As discussed above, the IP addresses can be seen to be a confounding of routing direction vectors and interface names. -->
Using the
terminology from the <xref target="nsrg-report">IRTF
Name Space Research Group Report</xref> and, e.g., the
unpublished Internet-Draft <xref
target="chiappa-endpoints">Endpoints and Endpoint Names </xref>,
the IP addresses currently embody the dual role
of locators and end-point identifiers. That is, each IP address
names a topological location in the Internet, thereby acting as
a routing direction vector, or locator. At the same time, the IP
address names the physical network interface currently located
at the point-of-attachment, thereby acting as a end-point
name.</t>
<t>In the HIP architecture, the end-point names and locators are
separated from each other. IP addresses continue to act as
locators. The Host Identifiers take the role of end-point
identifiers. It is important to understand that the end-point
names based on Host Identities are slightly different from
interface names; a Host Identity can be simultaneously reachable
through several interfaces.</t>
<t>The difference between the bindings of the logical entities
are illustrated in <xref target="figure-bindings"/>. Left side
illustrates the current TCP/IP architecture and right side the
HIP-based architecture.</t>
<figure anchor="figure-bindings">
<artwork src="draft-ietf-hip-arch-1.gif" type="gif">
Transport ---- Socket Transport ------ Socket
association | association |
| |
| |
| |
End-point | End-point --- Host Identity
\ | |
\ | |
\ | |
\ | |
Location --- IP address Location --- IP address
</artwork>
</figure>
<t>Architecturally, HIP provides for a different binding of
transport-layer protocols. That is, the transport-layer
associations, i.e., TCP connections and UDP associations, are
no longer bound to IP addresses but rather to Host
Identities. In practice, the Host Identities are exposed as
LSIs and HITs for legacy applications and the transport layer
to facilitate backward compatibility with existing networking
APIs and stacks.</t>
<section title="On the multiplicity of identities">
<t>A host may have multiple identities both at the client and
server side. This raises some additional concerns that are
addressed in this section.</t>
<t>For security reasons, it may be a bad idea to duplicate the
same Host Identity on multiple hosts because the compromise of
a single host taints the identities of the other hosts.
Management of machines with identical Host Identities may also
present other challenges and, therefore, it is advisable to
have a unique identity for each host.</t>
<t>Instead of duplicating identities, HIP opportunistic mode
can be employed, where the initiator leaves out the identifier
of the responder when initiating the key exchange and learns
it upon the completion of the exchange. The tradeoffs are
related to lowered security guarantees, but a benefit of the
approach is to avoid publishing of Host Identifiers in any
directories <xref target="komu-leap" />. The approach could also be used
for load balancing purposes at the HIP layer because the
identity of the responder can be decided dynamically during
the key exchange. Thus, the approach has
the potential to be used as a HIP-layer "anycast", either
directly between two hosts or indirectly through the
rendezvous service <xref target="komu-diss" />.</t>
<t>At the client side, a host may have multiple Host
Identities, for instance, for privacy purposes. Another reason
can be that the person utilizing the host employs different
identities for different administrative domains as an extra
security measure. If a HIP-aware middlebox, such as a
HIP-based firewall, is on the path between the client and
server, the user or the underlying system should carefully
choose the correct identity to avoid the firewall to
unnecessarily drop HIP-base connectivity <xref target="komu-diss"
/>.</t>
<t>Similarly, a server may have multiple Host Identities. For
instance, a single web server may serve multiple different
administrative domains. Typically, the distinction is
accomplished based on the DNS name, but also the Host Identity
could be used for this purpose. However, a more compelling
reason to employ multiple identities are HIP-aware firewalls
that are unable see the HTTP traffic inside the encrypted
IPsec tunnel. In such a case, each service could be configured
with a separate identity, thus allowing the firewall to
segregate the different services of the single web server from
each other <xref target="lindqvist-enterprise" />.</t>
<!--
<t>It is possible that a single physical computer hosts
several logical end-points. With HIP, each of these
end-points would have a distinct Host Identity. Furthermore,
since the transport associations are bound to Host Identities,
HIP provides for process migration and clustered servers.
That is, if a Host Identity is moved from one physical
computer to another, it is also possible to simultaneously
move all the transport associations without breaking them.
Similarly, if it is possible to distribute the processing of a
single Host Identity over several physical computers, HIP
provides for cluster based services without any changes at the
client end-point.</t> -->
</section>
</section>
<?rfc needLines="8"?>
<section anchor="control-plane" title="Control plane">
<t>HIP decouples control and data plane from each other. Two
end-hosts initialize the control plane using a key
exchange procedure called the base exchange. The procedure can
be assisted by new infrastructural intermediaries called
rendezvous or relay servers. In the event of IP address changes,
the end-hosts sustain control plane connectivity with mobility
and multihoming extensions. Eventually, the end-hosts terminate
the control plane and remove the associated state.</t>
<section title="Base exchange">
<t>The base exchange is a key exchange procedure that
authenticates the initiator and responder to each other using
their public keys. Typically, the initiator is the client-side
host and the responder is the server-side host. The roles are
used by the state machine of a HIP implementation, but discarded
upon successful completion.</t>
<t>
The exchange consists of four messages during which the hosts
also create symmetric keys to protect the control plane with
Hash-based message authentication codes (HMACs). The
keys can be also used to protect the data plane, and IPsec ESP
<xref target="RFC7402" /> is typically used as the data-plane protocol, albeit
HIP can also accommodate others. Both the
control and data plane are terminated using a closing procedure
consisting of two messages.
</t>
<t>In addition, the base exchange also includes a computational puzzle <xref
target="RFC7401" /> that the initiator must
solve. The responder chooses the difficulty of the puzzle which
permits the responder to delay new incoming initiators according
to local policies, for instance, when the responder is under
heavy load. The puzzle can offer some resiliency against DoS
attacks because the design of the puzzle mechanism allows the
responder to remain stateless until the very end of the base
exchange <xref target="aura-dos" />. HIP puzzles have also been
studied under steady-state DDoS attacks <xref
target="beal-dos" />, on multiple adversary models with varying
puzzle difficulties <xref target="tritilanunt-dos" /> and
with ephemeral Host Identities <xref target="komu-mitigation" />.
</t>
<!-- XX FIXME: MORE ON HICCUPS? -->
</section>
<section title="End-host mobility and multi-homing">
<t>HIP decouples the transport from the internetworking layer,
and binds the transport associations to the Host Identities
(actually through either the HIT or LSI). After the initial key
exchange, the HIP layer maintains transport-layer connectivity
and data flows using its <xref
target="I-D.ietf-hip-rfc5206-bis">mobility</xref> and <xref
target="I-D.ietf-hip-multihoming">multihoming</xref> extensions.
Consequently, HIP can provide for a degree of internetworking
mobility and multi-homing at a low infrastructure cost. HIP
mobility includes IP address changes (via any method) to either
party. Thus, a system is considered mobile if its IP address
can change dynamically for any reason like PPP, DHCP, IPv6
prefix reassignments, or a NAT device remapping its translation.
Likewise, a system is considered multi-homed if it has more than
one globally routable IP address at the same time. HIP links IP
addresses together, when multiple IP addresses correspond to the
same Host Identity. If one address becomes unusable, or a
more preferred address becomes available, existing transport
associations can easily be moved to another address.</t>
<t>When a node moves while communication is already on-going,
address changes are rather straightforward. The peer of the
mobile node can just accept a HIP or an integrity protected
ESP packet from any address and ignore the source address.
However, as discussed in <xref target="ssec-flooding" /> below,
a mobile node must send a HIP UPDATE packet to inform the
peer of the new address(es), and the peer must verify that the
mobile node is reachable through these addresses. This is
especially helpful for those situations where the peer node is
sending data periodically to the mobile node (that is,
re-starting a connection after the initial connection).</t>
</section>
<section title="Rendezvous mechanism">
<t>Establishing a contact to a mobile, moving node is slightly more
involved. In order to start the HIP exchange, the initiator
node has to know how to reach the mobile node. For instance,
the mobile node can employ Dynamic DNS <xref target="RFC2136"
/> to update its reachability information in the DNS. To avoid
the dependency to DNS, HIP provides its own HIP-specific
alternative: the HIP rendezvous mechanism as defined in <xref
target="I-D.ietf-hip-rfc5204-bis">HIP Rendezvous
specifications</xref>.</t>
<t>Using the HIP rendezvous extensions, the mobile node keeps
the rendezvous infrastructure continuously updated with its
current IP address(es). The mobile nodes trusts the
rendezvous mechanism in order to properly maintain their HIT
and IP address mappings.</t>
<t>The rendezvous mechanism is especially useful in scenarios
where both of the nodes are expected to change their address at the
same time. In such a case, the HIP
UPDATE packets will cross each other in the network and never
reach the peer node.</t>
</section>
<section title="Relay mechanism">
<t>The HIP relay mechanism <xref
target="I-D.ietf-hip-native-nat-traversal" /> is an
alternative to the HIP rendezvous mechanism. The HIP relay
mechanism is more suitable for IPv4 networks with NATs because
a HIP relay can forward all control and data plane
communications in order to guarantee successful NAT
traversal.</t>
</section>
<section title="Termination of the control plane">
<t>The control plane between two hosts is terminated using
a secure two message exchange as specified in <xref
target="RFC7401"> base exchange
specification</xref>. The
related state (i.e. host associations) should be removed upon
successful termination.</t>
</section>
</section>
<section anchor="esp" title="Data plane">
<t>The encapsulation format for the data
plane used for carrying the application-layer traffic
can be dynamically negotiated during the key
exchange. For instance, <xref target="RFC6078">HICCUPS
extensions</xref> define one way to transport application-layer
datagrams directly over the HIP control plane, protected by
asymmetric key cryptography. Also, S-RTP has been considered as
the data encapsulation protocol <xref target="hip-srtp"
/>. However, the most widely implemented method is the
Encapsulated Security Payload (ESP) <xref
target="RFC7402" /> that is protected by
symmetric keys derived during the key exchange. ESP Security
Associations (SAs) offer both confidentiality and integrity
protection, of which the former can be disabled during the key
exchange. In the future, other ways of transporting
application-layer data may be defined.</t>
<t>The ESP SAs are established and terminated between the
initiator and the responder hosts. Usually, the hosts create at
least two SAs, one in each direction (initiator-to-responder SA
and responder-to-initiator SA). If the IP addresses of either
host changes, the HIP mobility extensions can be used to
re-negotiate the corresponding SAs.</t>
<t>On the wire, the difference in the use of identifiers between
the HIP control and data plane is that the HITs are included in
all control packets, but not in the data plane when ESP is
employed. Instead, the ESP employs SPI numbers that act as
compressed HITs. Any HIP-aware middlebox (for instance, a
HIP-aware firewall) interested in the ESP based data plane
should keep track between the control and data plane identifiers
in order to associate them with each other.</t>
<!--
<t>HIP base exchange uses the cryptographic Host Identifiers to
set up a pair of ESP Security Associations (SAs) to enable ESP
in an end-to-end manner. While it would be possible, at least in
theory, to use some existing cryptographic protocol, such as
IKEv2 together with Host Identifiers, to establish the needed
SAs, HIP defines a new protocol. There are a number of
historical reasons for this, and there are also a few
architectural reasons. First, IKE (and IKEv2) were not
originally designed with middleboxes in mind. As adding a new
naming layer allows one to potentially add a new forwarding
layer (see <xref target="nat" />, below), it is very important
that the HIP provides mechanisms for middlebox
authentication.</t>
<t>Second, from a conceptual point of view, the IPsec Security
Parameter Index (SPI) in ESP provides a simple compression of
the HITs. This does require per-HIT-pair SAs (and SPIs), and a
decrease of policy granularity over other Key Management
Protocols, such as IKE and IKEv2. In other words, from an
architectural point of view, HIP only supports host-to-host
(or endpoint-to-endpoint) Security Associations.</t>
<t>Originally, as HIP is designed for host usage, not for gateways or so
called Bump-in-the-Wire (BITW) implementations, only ESP
transport mode is supported. An ESP SA pair is indexed by the
SPIs and the two HITs (both HITs since a system can have more
than one HIT). The SAs need not to be bound to IP addresses;
all internal control of the SA is by the HITs. Thus, a host can
easily change its address using Mobile IP, DHCP, PPP, or IPv6
readdressing and still maintain the SAs. Since the transports
are bound to the SA (via an LSI or a HIT), any active transport
is also maintained. Thus, real-world conditions like loss of a
PPP connection and its re-establishment or a mobile handover
will not require a HIP negotiation or disruption of transport
services <xref target="Bel1998" />.</t>
<t>It should be noted that there are already BITW implementations
of HIP providing virtual private network (VPN) services.
This is still consistent to the SA bindings above.</t>
-->
<t>Since HIP does not negotiate any SA lifetimes, all lifetimes
are subject to local policy. The only lifetimes a HIP implementation must
support are sequence number rollover (for replay protection),
and SA timeout. An SA times out if no packets are received using
that SA. Implementations may support lifetimes for the various
ESP transforms and other data-plane protocols.</t>
</section>
<section anchor="nat" title="HIP and NATs">
<!-- * UDP encap vs. HIP-aware NAT -->
<t>Passing packets between different IP addressing realms
requires changing IP addresses in the packet header. This may
occur, for example, when a packet is passed between the public
Internet and a private address space, or between IPv4 and IPv6
networks. The address translation is usually implemented as
<xref target="RFC3022">Network Address Translation (NAT)</xref>
or <xref target="RFC2766"> NAT Protocol translation
(NAT-PT)</xref>.</t>
<t>In a network environment where identification is based on the
IP addresses, identifying the communicating nodes is difficult
when NATs are employed because private address spaces
are overlapping. In other words, two hosts
cannot be distinguished from each other solely based on their IP
address. With HIP, the transport-layer end-points
(i.e. applications) are bound to unique Host Identities rather
than overlapping private addresses. This allows
two end-points to distinguish one other even when they are
located in different private address realms. Thus, the IP addresses are used
only for routing purposes and can be changed freely by NATs
when a packet between two HIP capable hosts traverses through multiple
private address realms.</t>
<t><xref target="I-D.ietf-hip-native-nat-traversal">NAT
traversal extensions for HIP</xref> can be used to realize the
actual end-to-end connectivity through NAT devices. To support
basic backward compatibility with legacy NATs, the extensions
encapsulate both HIP control and data plane in UDP. The
extensions define mechanisms for forwarding the two planes
through an intermediary host called HIP relay and procedures to
establish direct end-to-end connectivity by penetrating
NATs. Besides this "native" NAT traversal mode for HIP, other
NAT traversal mechanisms have been successfully utilized, such
as Teredo <xref target="varjonen-split" />.</t>
<t>Besides legacy NATs, a HIP-aware NAT has been designed and
implemented <xref target="ylitalo-spinat" />. For a HIP-based flow, a HIP-aware
NAT or NAT-PT system tracks the mapping of HITs, and the
corresponding ESP SPIs, to an IP address. The NAT system has to
learn mappings both from HITs and from SPIs to IP addresses.
Many HITs (and SPIs) can map to a single IP address on a NAT,
simplifying connections on address poor NAT interfaces. The NAT
can gain much of its knowledge from the HIP packets themselves;
however, some NAT configuration may be necessary.</t>
<!--
<t>NAT systems cannot touch the datagrams within the ESP
envelope, thus application-specific address translation must be
done in the end systems. It should be noted that HIP provides
for 'Distributed NAT', and uses the HIT or the LSI as a
placeholder for embedded IP addresses.</t> -->
<section title="HIP and Upper-layer checksums">
<t>There is no way for a host to know if any of the IP
addresses in an IP header are the addresses used to calculate
the TCP checksum. That is, it is not feasible to calculate
the TCP checksum using the actual IP addresses in the pseudo
header; the addresses received in the incoming packet are not
necessarily the same as they were on the sending host.
Furthermore, it is not possible to recompute the upper-layer
checksums in the NAT/NAT-PT system, since the traffic is ESP
protected. Consequently, the TCP and UDP checksums are
calculated using the HITs in the place of the IP addresses in
the pseudo header. Furthermore, only the IPv6 pseudo header
format is used. This provides for IPv4 / IPv6 protocol
translation.</t>
</section>
</section>
<section title="Multicast">
<t>A number of studies investigating HIP-based multicast
have been published (including <xref target="shields-hip" />, <xref
target="xueyong-hip" />, <xref target="xueyong-hip" />, <xref
target="amir-hip" />, <xref target="kovacshazi-host" /> and
<xref target="xueyong-secure" />). In particular, so-called Bloom filters,
that allow compressing of multiple labels into small
data structures, may be a promising way forward <xref
target="sarela-bloom" />. However, the different schemes have
not been adopted by the HIP working group (nor the HIP research
group in IRTF), so the details are not further elaborated here.</t>
</section>
<section title="HIP policies">
<t>There are a number of variables that influence the HIP
exchange that each host must support. All HIP implementations
should support at least 2 HIs, one to publish in DNS or similar
directory service and an unpublished one for anonymous usage.
Although unpublished HIs will be rarely used as responder HIs,
they are likely to be common for initiators. Support for multiple
HIs is recommended. This provides new challenges for systems
or users to decide which type of HI to expose when they start
a new session.</t>
<t>Opportunistic mode (where the initiator starts a HIP exchange
without prior knowledge of the responder's HI) presents a
security tradeoff. At the expense of being subject to MITM
attacks, the opportunistic mode allows the initiator to learn
the identity of the responder during communication rather than
from an external directory. Opportunistic mode can be used for
registration to HIP-based services <xref
target="I-D.ietf-hip-rfc5203-bis" /> (i.e. utilized by HIP for
its own internal purposes) or by the application layer <xref
target="komu-leap" />. For security reasons, especially the
latter requires some involvement from the user to accept the
identity of the responder similar to how SSH prompts the
user when connecting to a server for the first time <xref
target="pham-leap" />. In practice, this can be realized
in end-host based firewalls in the case of legacy applications
<xref target="karvonen-usable" /> or with <xref
target="RFC6317">native APIs for HIP APIs</xref> in the case of
HIP-aware applications.</t>
<t>Many initiators would want to use a different HI for
different responders. The implementations should provide for a policy mapping of
initiator HITs to responder HITs. This policy should
also include preferred transforms and local lifetimes. </t>
<t>Responders would need a similar policy, describing the hosts
allowed to participate in HIP exchanges, and the preferred
transforms and local lifetimes.</t>
</section>
<section title="Design considerations">
<section title="Benefits of HIP">
<t>In the beginning, the network layer protocol (i.e., IP) had
the following four "classic" invariants:
<list style="numbers">
<t>Non-mutable: The address sent is the address
received.</t>
<t>Non-mobile: The address doesn't change during the course
of an "association".</t>
<t>Reversible: A return header can always be formed by
reversing the source and destination addresses.</t>
<t>Omniscient: Each host knows what address a partner host
can use to send packets to it.</t>
</list>
</t>
<t>Actually, the fourth can be inferred from 1 and 3, but it is
worth mentioning explicitly for reasons that will be obvious soon if not
already.</t>
<t>In the current "post-classic" world, we are intentionally
trying to get rid of the second invariant (both for mobility and
for multi-homing), and we have been forced to give up the first
and the fourth. <xref target="RFC3102">Realm Specific IP</xref>
is an attempt to reinstate the fourth invariant without the
first invariant. IPv6 is an attempt to reinstate the first
invariant.</t>
<t>Few client-side systems on the Internet have DNS names that are
meaningful. That is, if they have a Fully Qualified Domain Name
(FQDN), that name typically belongs to a NAT device or a dial-up
server, and does not really identify the system itself but its
current connectivity. FQDNs (and their extensions as email
names) are application-layer names; more frequently naming
services than particular systems. This is why many systems on
the Internet are not registered in the DNS; they do not have
services of interest to other Internet hosts.</t>
<t>DNS names are references to IP addresses. This only
demonstrates the interrelationship of the networking and
application layers. DNS, as the Internet's only deployed and
distributed database, is also the repository of other namespaces,
due in part to DNSSEC and application specific key records.
Although each namespace can be stretched (IP with v6, DNS with
KEY records), neither can adequately provide for host
authentication or act as a separation between internetworking
and transport layers.</t>
<t>The Host Identity (HI) namespace fills an important gap
between the IP and DNS namespaces. An interesting thing about
the HI is that it actually allows a host to give up all but the
3rd network-layer invariant. That is to say, as long as the
source and destination addresses in the network-layer protocol
are reversible, HIP takes care of host identification, and
reversibility allows a local host to receive a packet back from
a remote host. The address changes occurring during NAT transit
(non-mutable) or host movement (non-omniscient or non-mobile)
can be managed by the HIP layer.</t>
<t>With the exception of High-Performance Computing applications,
the Sockets API is the most common way to develop network
applications. Applications use the Sockets API either directly
or indirectly through some libraries or frameworks. However, the
Sockets API is based on the assumption of static IP addresses,
and DNS with its lifetime values was invented at later stages
during the evolution of the Internet. Hence, the Sockets API
does not deal with the lifetime of addresses <xref
target="RFC6250" />. As the majority of the end-user equipment is
mobile today, their addresses are effectively ephemeral, but the
Sockets API still gives a fallacious illusion of persistent IP
addresses to the unwary developer. HIP can be used to solidify
this illusion because HIP provides persistent surrogate
addresses to the application layer in the form of LSIs and
HITs.</t>
<t>The persistent identifiers as provided by HIP are useful in
multiple scenarios (see, e.g., <xref target="ylitalo-diss" /> or
<xref target="komu-diss" />, for a more elaborate
discussion):</t>
<t>
<list style="symbols">
<t>When a mobile host moves physically between two different
WLAN networks and obtains a new address, an application using
the identifiers remains isolated regardless of the topology changes
while the underlying HIP layer re-establishes connectivity
(i.e. a horizontal handoff).</t>
<t>Similarly, the application utilizing the identifiers
remains again unaware of the topological changes when the
underlying host equipped with WLAN and cellular network
interfaces switches between the two different access
technologies (i.e. a vertical handoff).</t>
<t>Even when hosts are located in private address realms,
applications can uniquely distinguish different hosts from
each other based on their identifiers. In other words, it can
be stated that HIP improves Internet transparency
for the application layer <xref target="komu-diss" />.</t>
<t>Site renumbering events for services can occur due to
corporate mergers or acquisitions, or by changes in Internet
Service Provider. They can involve changing the entire
network prefix of an organization, which is problematic due
to hard-coded addresses in service configuration files or
cached IP addresses at the client side <xref target="RFC5887"
/>. Considering such human errors, a site employing
location-independent identifiers as promoted by HIP may
experience less problems while renumbering their network.
</t>
<t>More agile IPv6 interoperability can be achieved,
as discussed in <xref target="lsi" />. IPv6-based applications can
communicate using HITs with IPv4-based applications that are
using LSIs. Additionally, the underlying network type (IPv4 or IPv6)
becomes independent of the addressing family of the
application.</t>
<t>HITs (or LSIs) can be used in IP-based access control
lists as a more secure replacement for IPv6
addresses. Besides security, HIT based access control has two
other benefits. First, the use of HITs can potentially halve the size of access control lists
because separate rules for IPv4 are not
needed <xref target="komu-diss" />. Second, HIT-based configuration
rules in HIP-aware middleboxes remain static and independent
of topology changes, thus simplifying administrative efforts
particularly for mobile environments. For instance, the
benefits of HIT based access control have been harnessed in the
case of HIP-aware firewalls, but can be utilized
directly at the end-hosts as well <xref target="RFC6538" />.</t>
</list>
</t>
<t>While some of these benefits could be and have been
redundantly implemented by individual applications, providing
such generic functionality at the lower layers is useful because
it reduces software development effort and networking software
bugs (as the layer is tested with multiple applications). It
also allows the developer to focus on building the application
itself rather than delving into the intricacies of mobile
networking, thus facilitating separation of concerns.</t>
<t>HIP could also be realized by combining a number of different
protocols, but the complexity of the resulting software may
become substantially larger, and the interaction between multiple
possibly layered protocols may have adverse effects on latency
and throughput. It is also worth noting that virtually nothing
prevents realizing the HIP architecture, for instance, as an
application-layer library, which has been actually implemented
in the past <xref target="xin-hip-lib" />. However, the tradeoff
in moving the HIP layer to the application layer is that legacy
applications may not be supported.</t>
<!--
<t>Since all systems can have a Host Identity, every system can
have an entry in the DNS. The mobility features in HIP make it
attractive to trusted 3rd parties to offer rendezvous
servers.</t>
-->
</section>
<section title="Drawbacks of HIP">
<t>In computer science, many problems can be solved with an
extra layer of indirection. However, the indirection always
involves some costs as there is no such a thing as "free lunch". In
the case of HIP, the main costs could be stated as follows:</t>
<t>
<list style="symbols">
<t>In general, a new layer and a new namespace always involve
some initial effort in terms of implementation,
deployment and maintenance. Some education of developers and administrators may
also be needed. However, the HIP community at the IETF has
spent years in experimenting, exploring, testing,
documenting and implementing HIP to ease the adoption costs.
</t>
<t>HIP decouples identifier and locator roles of IP
addresses. Consequently, a mapping mechanism is needed to
associate them together. A failure to map a HIT to its
corresponding locator may result in failed connectivity
because a HIT is "flat" by its nature and cannot be looked
up from the hierarchically organized DNS. HITs are flat by
design due to a security tradeoff. The more bits are
allocated for the hash in the HIT, the less likely there
will be (malicious) collisions.</t>
<t>From performance viewpoint, HIP control and data plane
processing introduces some overhead in terms of throughput and
latency as elaborated below.</t>
</list>
</t>
<t>The key exchange introduces some extra latency (two round
trips) in the initial transport layer connection establishment between two hosts.
With TCP, additional delay occurs if the underlying network stack implementation drops
the triggering SYN packet during the key exchange.
The same cost may also occur during HIP handoff
procedures. However, subsequent TCP sessions using the same HIP association will not bear this cost (within the key lifetime).
Both the key exchange and handoff penalties can be minimized by caching TCP
packets. The latter case can further be optimized with
TCP user timeout extensions <xref target="RFC5482" /> as described in further
detail by Schütz et al <xref target="schuetz-intermittent" />.</t>
<t>The most CPU-intensive operations involve the use of the
asymmetric keys and Diffie-Hellman key derivation at the control
plane, but this occurs only during the key exchange, its
maintenance (handoffs, refreshing of key material) and tear down
procedures of HIP associations. The data plane is typically
implemented with ESP because it has a smaller overhead due to symmetric key
encryption. Naturally, even ESP involves some overhead in terms of
latency (processing costs) and throughput (tunneling) (see
e.g. <xref target="ylitalo-diss" /> for a performance
evaluation).</t>
</section>
<section title="Deployment and adoption considerations">
<t>This section describes some deployment and adoption
considerations related to HIP from a technical perspective.</t>
<section title="Deployment analysis">
<t>HIP has commercially been utilized at Boeing airplane factory
for their internal purposes <xref target="paine-hip" />. It has
been included in a security product called Tofino to support
layer-two Virtual Private Networks <xref target="henderson-vpls"
/> to facilitate, e.g, supervisory control and data acquisition
(SCADA) security. However, HIP has not been a "wild success"
<xref target="RFC5218" /> in the Internet as argued by Levä et
al <xref target="leva-barriers" />. Here, we briefly highlight
some of their findings based on interviews with 19 experts from
the industry and academia.</t>
<t>From a marketing perspective, the demand for HIP has been low
and substitute technologies have been favored. Another
identified reason has been that some technical misconceptions
related to the early stages of HIP specifications still
persist. Two identified misconceptions are that HIP does not
support NAT traversal, and that HIP must be implemented in the OS
kernel. Both of these claims are untrue; HIP does have NAT
traversal extensions <xref
target="I-D.ietf-hip-native-nat-traversal" />, and kernel
modifications can be avoided with modern operating systems by
diverting packets for userspace processing.
</t>
<t>The analysis by Levä et al clarifies infrastructural requirements for
HIP. In a minimal set up, a client and server machine have to
run HIP software. However, to avoid manual configurations,
usually DNS records for HIP are set up. For instance, the
popular DNS server software Bind9 does not require any changes
to accommodate DNS records for HIP because they can be supported
in binary format in its configuration files <xref target="RFC6538" />. HIP
rendezvous servers and firewalls are optional. No changes are
required to network address points, NATs, edge routers or core
networks. HIP may require holes in legacy firewalls.
</t>
<t>The analysis also clarifies the requirements for the host
components that consist of three parts. First, a HIP control
plane component is required, typically implemented as a
userspace daemon. Second, a data plane component is needed. Most
HIP implementations utilize the so called BEET mode of ESP that
has been available since Linux kernel 2.6.27, but is included
also as a userspace component in a few of the
implementations. Third, HIP systems usually provide a DNS proxy
for the local host that translates HIP DNS records to LSIs and
HITs, and communicates the corresponding locators to HIP
userspace daemon. While the third component is not
mandatory, it is very useful for avoiding manual
configurations. The three components are further described in
the <xref target="RFC6538">HIP experiment report</xref>.</t>
<t>Based on the interviews, Levä et al suggest further
directions to facilitate HIP deployment. Transitioning the HIP
specifications to the standards track may help, but other
measures could be taken. As a more radical measure, the authors
suggest to implement HIP as a purely application-layer library
<xref target="xin-hip-lib" /> or other kind of middleware. On
the other hand, more conservative measures include focusing on
private deployments controlled by a single stakeholder. As a
more concrete example of such a scenario, HIP could be used by a
single service provider to facilitate secure connectivity between its
servers <xref target="komu-cloud" />.
</t>
</section>
<section anchor="MACsec" title="HIP in 802.15.4 networks">
<t>The IEEE 802 standards have been defining MAC layered security. Many
of these standards use EAP <xref target="RFC3748"></xref>
as a Key Management System (KMS) transport, but some like IEEE
802.15.4 <xref target="IEEE.802-15-4.2011"></xref> leave the
KMS and its transport as "Out of Scope".</t>
<t>HIP is well suited as a KMS in these environments:
<list style="symbols">
<t>HIP is independent of IP addressing and can be directly
transported over any network protocol.</t>
<t>Master Keys in 802 protocols are commonly pair-based with
group keys transported from the group controller using pair-wise
keys.</t>
<t>AdHoc 802 networks can be better served by a peer-to-peer
KMS than the EAP client/server model.</t>
<t>Some devices are very memory constrained and a common KMS
for both MAC and IP security represents a considerable code
savings.</t>
</list>
</t>
</section>
</section>
<section title="Answers to NSRG questions">
<t>The IRTF Name Space Research Group has posed a number of
evaluating questions in <xref
target="nsrg-report">their report</xref>. In this
section, we provide answers to these questions.
<list style="numbers">
<t>How would a stack name improve the overall
functionality of the Internet?
<list style="empty">
<t>HIP decouples the internetworking layer from the
transport layer, allowing each to evolve separately.
The decoupling makes end-host mobility and
multi-homing easier, also across IPv4 and IPv6
networks. HIs make network renumbering easier, and
they also make process migration and clustered servers
easier to implement. Furthermore, being cryptographic
in nature, they provide the basis for solving the
security problems related to end-host mobility and
multi-homing.</t>
</list>
</t>
<t>What does a stack name look like?
<list style="empty">
<t>A HI is a cryptographic public key. However,
instead of using the keys directly, most protocols use
a fixed size hash of the public key.</t>
</list>
</t>
<t>What is its lifetime?
<list style="empty">
<t>HIP provides both stable and temporary Host
Identifiers. Stable HIs are typically long lived,
with a lifetime of years or more. The lifetime of
temporary HIs depends on how long the upper-layer
connections and applications need them, and can range
from a few seconds to years.</t>
</list>
</t>
<t>Where does it live in the stack?
<list style="empty">
<t>The HIs live between the transport and
internetworking layers.</t>
</list>
</t>
<t>How is it used on the end points?
<list style="empty">
<t>The Host Identifiers may be used directly or
indirectly (in the form of HITs or LSIs) by
applications when they access network services.
Additionally, the Host Identifiers, as public keys,
are used in the built in key agreement protocol,
called the HIP base exchange, to authenticate the
hosts to each other.</t>
</list>
</t>
<t>What administrative infrastructure is needed to support
it?
<list style="empty">
<t>In some environments, it is possible to use HIP
opportunistically, without any infrastructure.
However, to gain full benefit from HIP, the HIs must
be stored in the DNS or a PKI, and a new rendezvous
mechanism is needed <xref target="I-D.ietf-hip-rfc5205-bis" />.</t>
</list>
</t>
<t>If we add an additional layer would it make the address
list in SCTP unnecessary?
<list style="empty">
<t>Yes</t>
</list>
</t>
<t>What additional security benefits would a new naming
scheme offer?
<list style="empty">
<t>HIP reduces dependency on IP addresses, making the
so called address ownership <xref target="Nik2001" />
problems easier to solve. In practice, HIP provides
security for end-host mobility and multi-homing.
Furthermore, since HIP Host Identifiers are public
keys, standard public key certificate infrastructures
can be applied on the top of HIP.</t>
</list>
</t>
<t>What would the resolution mechanisms be, or what
characteristics of a resolution mechanisms would be
required?
<list style="empty">
<t>For most purposes, an approach where DNS names are
resolved simultaneously to HIs and IP addresses is
sufficient. However, if it becomes necessary to
resolve HIs into IP addresses or back to DNS names, a
flat resolution infrastructure is needed. Such an
infrastructure could be based on the ideas of
Distributed Hash Tables, but would require significant
new development and deployment.</t>
</list>
</t>
</list>
</t>
</section>
</section>
<section title="Security considerations">
<t>This section includes discussion on some issues and solutions
related to security in the HIP architecture.</t>
<section title="MiTM Attacks">
<t>HIP takes advantage of the new Host Identity paradigm to
provide secure authentication of hosts and to provide a fast key
exchange for ESP. HIP also attempts to limit the exposure of
the host to various denial-of-service (DoS) and
man-in-the-middle (MitM) attacks. In so doing, HIP itself is
subject to its own DoS and MitM attacks that potentially could
be more damaging to a host's ability to conduct business as
usual.</t>
<t>Resource exhausting denial-of-service attacks take advantage
of the cost of setting up a state for a protocol on the
responder compared to the 'cheapness' on the initiator. HIP
allows a responder to increase the cost of the start of state on
the initiator and makes an effort to reduce the cost to the
responder. This is done by having the responder start the
authenticated Diffie-Hellman exchange instead of the initiator,
making the HIP base exchange 4 packets long. The first packet
sent by the responder can be prebuilt to further mitigate the
costs. This packet also includes a computational puzzle that can
optionally be used to further delay the initiator, for instance,
when the responder is overloaded. The details are explained in
the <xref target="RFC7401">base exchange
specification</xref>.</t>
<!--
<t>HIP optionally supports opportunistic negotiation. That is,
if a host receives a start of transport without a HIP
negotiation, it can attempt to force a HIP exchange before
accepting the connection. This has the potential for DoS
attacks against both hosts. If the method to force the start of
HIP is expensive on either host, the attacker need only spoof a
TCP SYN. This would put both systems into the expensive
operations. HIP avoids this attack by having the responder send
a simple R1 packet that it can pre-build. Since this packet is
fixed and easily replayed, the initiator only reacts to it if it
has just started a connection to the responder.</t> -->
<t>Man-in-the-middle (MitM) attacks are difficult to defend against,
without third-party authentication. A skillful MitM could
easily handle all parts of the HIP base exchange, but HIP
indirectly provides the following protection from a MitM attack.
If the responder's HI is retrieved from a signed DNS zone or
securely obtained by some other means, the initiator can use this to
authenticate the signed HIP packets. Likewise, if the
initiator's HI is in a secure DNS zone, the responder can
retrieve it and validate the signed HIP packets. However, since
an initiator may choose to use an unpublished HI, it knowingly
risks a MitM attack. The responder may choose not to accept a
HIP exchange with an initiator using an unknown HI.</t>
<t>Other types of MitM attacks against HIP can be mounted using
ICMP messages that can be used to signal about problems. As a
overall guideline, the ICMP messages should be considered as
unreliable "hints" and should be acted upon only after
timeouts. The exact attack scenarios and countermeasures are
described in full detail the <xref target="RFC7401">base
exchange specification</xref>.</t>
<t>The need to support multiple hashes for generating the HIT
from the HI affords the MitM to mount a potentially powerful downgrade
attack due to the a-priori need of the HIT in the HIP base
exchange. The base exchange has been augmented to deal with
such an attack by restarting on detecting the attack. At
worst this would only lead to a situation in which the
base exchange would never finish (or would be aborted after
some retries). As a drawback, this leads to an 6-way base
exchange which may seem bad at first. However, since this
only occurs in an attack scenario and since the attack can
be handled (so it is not interesting to mount anymore), we
assume the subsequent messages do not represent a security threat. Since
the MitM cannot be successful with a downgrade attack, these
sorts of attacks will only occur as 'nuisance' attacks. So,
the base exchange would still be usually just four packets
even though implementations must be prepared to protect
themselves against the downgrade attack.</t>
<t>In HIP, the Security Association for ESP is indexed by the
SPI; the source address is always ignored, and the destination
address may be ignored as well. Therefore, HIP-enabled
Encapsulated Security Payload (ESP) is IP address independent.
This might seem to make attacking easier, but ESP with
replay protection is already as well protected as possible, and
the removal of the IP address as a check should not increase the
exposure of ESP to DoS attacks.</t>
</section>
<section anchor="ssec-flooding" title="Protection against flooding attacks">
<t>Although the idea of informing about address changes by
simply sending packets with a new source address appears
appealing, it is not secure enough. That is, even if HIP does
not rely on the source address for anything (once the base
exchange has been completed), it appears to be necessary to
check a mobile node's reachability at the new address before
actually sending any larger amounts of traffic to the new
address.</t>
<t>Blindly accepting new addresses would potentially lead to
flooding Denial-of-Service attacks against third parties <xref
target="RFC4225" />. In a distributed flooding attack an
attacker opens high volume HIP connections with a large number
of hosts (using unpublished HIs), and then claims to all of
these hosts that it has moved to a target node's IP address.
If the peer hosts were to simply accept the move, the result
would be a packet flood to the target node's address. To
prevent this type of attack, HIP mobility extensions include a return routability
check procedure where the reachability of a node is separately
checked at each address before using the address for larger
amounts of traffic.</t>
<t>A credit-based authorization approach <xref target="I-D.ietf-hip-rfc5206-bis">
for host mobility with the Host Identity Protocol</xref>
can be used between hosts for sending data prior to completing the address
tests. Otherwise, if HIP is used between two hosts that fully
trust each other, the hosts may optionally decide to skip the
address tests. However, such performance optimization must be
restricted to peers that are known to be trustworthy and
capable of protecting themselves from malicious software.</t>
</section>
<section title="HITs used in ACLs">
<t>At end-hosts, HITs can be used in IP-based access control
lists at the application and network layers. At middleboxes,
HIP-aware firewalls <xref target="lindqvist-enterprise" /> can use HITs or public
keys to control both ingress and egress access to networks or
individual hosts, even in the presence of mobile devices
because the HITs and public keys are topologically
independent. As discussed earlier in <xref target="esp"
/>, once a HIP session has been established, the SPI value in
an ESP packet may be used as an index, indicating the HITs.
In practice, firewalls can inspect HIP packets to learn of the
bindings between HITs, SPI values, and IP addresses. They can
even explicitly control ESP usage, dynamically opening ESP
only for specific SPI values and IP addresses. The signatures
in HIP packets allow a capable firewall to ensure that the HIP
exchange is indeed occurring between two known hosts. This
may increase firewall security.</t>
<t>A potential drawback of HITs in ACLs is their 'flatness'
means they cannot be aggregated, and this could potentially
result in larger table searches in HIP-aware firewalls. A
way to optimize this could be to utilize Bloom filters for
grouping of HITs <xref target="sarela-bloom" />. However, it
should be noted that it is also easier to exclude individual,
misbehaving hosts out when the firewall rules concern
individual HITs rather than groups.</t>
<!-- <t>[add here wildcarding]</t> -->
<t>There has been considerable bad experience with distributed
ACLs that contain public key related material, for example,
with SSH. If the owner of a key needs to revoke it for any
reason, the task of finding all locations where the key is
held in an ACL may be impossible. If the reason for the
revocation is due to private key theft, this could be a
serious issue.</t>
<t>A host can keep track of all of its partners that might use
its HIT in an ACL by logging all remote HITs. It should only
be necessary to log responder hosts. With this information,
the host can notify the various hosts about the change to the
HIT. There have been attempts to develop a secure method to
issue the HIT revocation notice <xref target="zhang-revocation" />.</t>
<t>Some of the HIP-aware middleboxes, such as firewalls <xref
target="lindqvist-enterprise" /> or NATs <xref
target="ylitalo-spinat" />, may observe the on-path traffic
passively. Such middleboxes are transparent by their nature
and may not get a notification when a host moves to a
different network. Thus, such middleboxes should maintain soft
state and timeout when the control and data plane between two
HIP end-hosts has been idle too long. Correspondingly, the two
end-hosts may send periodically keepalives, such as UPDATE
packets or ICMP messages inside the ESP tunnel, to sustain
state at the on-path middleboxes.</t>
<t>One general limitation related to end-to-end encryption is
that middleboxes may not be able to participate to the
protection of data flows. While the issue may affect
also other protocols, Heer at al <xref target="heer-end-host"
/> have analyzed the problem in the context of HIP. More
specifically, when ESP is used as the data-plane protocol for HIP, the
association between the control and data plane is weak and can
be exploited under certain assumptions. In the
scenario, the attacker has already gained access to the target
network protected by a HIP-aware firewall, but wants to
circumvent the HIP-based firewall. To achieve this, the
attacker passively observes a base exchange between two HIP
hosts and later replays it. This way, the attacker manages to
penetrate the firewall and can use a fake ESP tunnel to
transport its own data. This is possible because the firewall
cannot distinguish when the ESP tunnel is valid. As a
solution, HIP-aware middleboxes may participate to the control
plane interaction by adding random nonce parameters to the
control traffic, which the end-hosts have to sign to
guarantee the freshness of the control traffic <xref
target="heer-midauth" />. As an alternative, extensions for
transporting data plane directly over the control plane can be
used <xref target="RFC6078" />.
</t>
<!--
<t>HIP-aware NATs, however, are transparent to the HIP aware
systems by design. Thus, the host may find it difficult to
notify any NAT that is using a HIT in an ACL. Since most
systems will know of the NATs for their network, there should
be a process by which they can notify these NATs of the change
of the HIT. This is mandatory for systems that function as
responders behind a NAT. In a similar vein, if a host is
notified of a change in a HIT of an initiator, it should
notify its NAT of the change. In this manner, NATs will be
updated with the HIT change.</t> -->
</section>
<section title="Alternative HI considerations">
<t>The definition of the Host Identifier states that the HI
need not be a public key. It implies that the HI could be any
value; for example a FQDN. This document does not describe
how to support such a non-cryptographic HI, but examples of
such protocol variants do exist (<xref target="urien-rfid" />,
<xref target="urien-rfid-draft" />). A non-cryptographic HI
would still offer the services of the HIT or LSI for NAT
traversal. It would be possible to carry HITs in HIP packets
that had neither privacy nor authentication. Such schemes may
be employed for resource constrained devices, such as small
sensors operating on battery power, but are not further
analyzed here.</t>
<t>If it is desirable to use HIP in a low security situation
where public key computations are considered expensive, HIP
can be used with very short Diffie-Hellman and Host Identity
keys. Such use makes the participating hosts vulnerable to
MitM and connection hijacking attacks. However, it does not
cause flooding dangers, since the address check mechanism
relies on the routing system and not on cryptographic
strength.</t>
</section>
</section>
<section title="IANA considerations">
<t> This document has no actions for IANA.</t>
</section>
<section title="Acknowledgments">
<t>For the people historically involved in the early stages of
HIP, see the Acknowledgments section in the
Host Identity Protocol specification.</t>
<t>During the later stages of this document, when the editing
baton was transferred to Pekka Nikander, the comments from the
early implementers and others, including Jari Arkko, Tom
Henderson, Petri Jokela, Miika Komu, Mika Kousa, Andrew
McGregor, Jan Melen, Tim Shepard, Jukka Ylitalo, Sasu Tarkoma,
and Jorma Wall, were invaluable. Also, the comments from Lars Eggert,
Spencer Dawkins and Dave Crocker were also useful.</t>
<t>The authors want to express their special thanks to
Tom Henderson, who took the burden of editing the document
in response to IESG comments at the time when both of the
authors were busy doing other things. Without his perseverance
original document might have never made it as RFC4423.</t>
<t>This main effort to update and move HIP forward within the
IETF process owes its impetuous to a number of HIP development
teams. The authors are grateful for Boeing, Helsinki Institute
for Information Technology (HIIT), NomadicLab of Ericsson, and
the three universities: RWTH Aachen, Aalto and University of
Helsinki, for their efforts. Without their collective efforts
HIP would have withered as on the IETF vine as a nice
concept.</t>
<t>Thanks also for Suvi Koskinen for her help with proofreading
and with the reference jungle.</t>
</section>
<section title="Changes from RFC 4423">
<t>In a nutshell, the changes from <xref target="RFC4423"> RFC
4423</xref> are mostly editorial, including clarifications on
topics described in a difficult way and omitting some of the
non-architectural (implementation) details that are already
described in other documents. A number of missing references to
the literature were also added. New topics include the drawbacks
of HIP, discussion on 802.15.4 and MAC security, deployment
considerations and description of the base exchange.</t>
</section>
</middle>
<back>
<references title="Normative References">
&RFC7343;
&RFC7401;
&RFC7402;
&RFC5203-bis;
&RFC5204-bis;
&RFC5205-bis;
&RFC5206-bis;
&RFC6253-bis;
&RFC5482;
<!-- &hip-nat; -->
<?rfc include="reference.I-D.ietf-hip-multihoming.xml"?>
<?rfc include="reference.I-D.ietf-hip-native-nat-traversal.xml"?>
</references>
<references title="Informative references">
&RFC2136;
&RFC2535;
&RFC2766;
&RFC3022;
&RFC3102;
&RFC3748;
<!-- &RFC4025; -->
&RFC4225;
&RFC4306;
&RFC4423;
&RFC5218;
&RFC5338;
&RFC5887;
&RFC6078;
&RFC6250;
&RFC6281;
&RFC6317;
&RFC6537;
&RFC6538;
<!-- &nsrg-report; -->
<!-- &IEEE.802-15-4.2011; -->
<!-- Removed per Russ Housley IESG comment
&I-D.ietf-hip-mm;
-->
<reference anchor="nsrg-report">
<front>
<title>What's In A Name:Thoughts from the NSRG</title>
<author initials="E" surname="Lear" fullname="Eliot Lear"><organization/></author>
<author initials="R" surname="Droms" fullname="Ralph Droms"><organization/></author>
<date month="September" day="22" year="2003"/>
</front><seriesInfo name="Internet-Draft" value="draft-irtf-nsrg-report-10"/>
<format type="TXT" target="http://tools.ietf.org/id/draft-irtf-nsrg-report-10.txt"/>
</reference>
<reference anchor="IEEE.802-15-4.2011" target="http://standards.ieee.org/getieee802/download/802.15.4-2011.pdf">
<front>
<title>Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements - Part 15.4: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Low-Rate Wireless Personal Area Networks (WPANs)</title>
<author fullname="Institute of Electric and Electronic Engineers"><organization/></author>
<date month="September" year="2011"/>
</front><seriesInfo name="IEEE" value="Standard 802.15.4"/>
</reference>
<reference anchor="chiappa-endpoints">
<front>
<title>Endpoints and Endpoint Names: A Proposed Enhancement
to the Internet Architecture</title>
<author initials="J. N." surname="Chiappa">
<organization />
</author>
<date year="1999" />
</front>
<seriesInfo name="URL"
value="http://www.chiappa.net/~jnc/tech/endpoints.txt" />
<format type="txt"
target="http://www.chiappa.net/~jnc/tech/endpoints.txt" />
</reference>
<reference anchor="Nik2001">
<front>
<title>Denial-of-Service, Address Ownership, and Early
Authentication in the IPv6 World</title>
<author initials="P." surname="Nikander">
<organization />
</author>
<date year="2002" />
</front>
<seriesInfo name="in Proceesings of"
value="Security Protocols, 9th International Workshop" />
<seriesInfo name=""
value="Cambridge, UK, April 25-27 2001" />
<seriesInfo name="LNCS" value="2467" />
<seriesInfo name="pp." value="12-26" />
<seriesInfo name="" value="Springer" />
<format type="pdf"
target="http://www.tml.hut.fi/~pnr/publications/cam2001.pdf"
/>
</reference>
<!--
<reference anchor="Bel1998">
<front>
<title>EIDs, IPsec, and HostNAT</title>
<author initials="S." surname="Bellovin">
<organization />
</author>
<date year="1998" month="March" />
</front>
<seriesInfo name="in Proceedings of"
value="41th IETF, Los Angeles, CA" />
<seriesInfo name="URL"
value="http://www1.cs.columbia.edu/~smb/talks/hostnat.pdf" />
<format type="pdf"
target="http://www1.cs.columbia.edu/~smb/talks/hostnat.pdf"
/>
</reference>
-->
<reference anchor="urien-rfid">
<front>
<title>HIP-based RFID Networking Architecture</title>
<author initials="P." surname="Urien"></author>
<author initials="H." surname="Chabanne"></author>
<author initials="M." surname="Bouet"></author>
<author initials="D.O." surname="de Cunha"></author>
<author initials="V." surname="Guyot"></author>
<author initials="G." surname="Pujolle"></author>
<author initials="P." surname="Paradinas"></author>
<author initials="E." surname="Gressier"></author>
<author initials="J.-F." surname="Susini"></author>
<date year="2007" month="July" />
</front>
<seriesInfo name="IFIP International Conference on Wireless and Optical Communications Networks," value="DOI: 10.1109/WOCN.2007.4284140" />
</reference>
<reference anchor="komu-leap">
<front>
<title>Leap-of-Faith Security is Enough for IP Mobility</title>
<author initials="M." surname="Komu"></author>
<author initials="J." surname="Lindqvist"></author>
<date year="2009" month="January" />
</front>
<seriesInfo name="6th Annual IEEE Consumer Communications and Networking Conference IEEE CCNC 2009, Las Vegas, Nevada," value="" />
</reference>
<reference anchor="komu-diss">
<front>
<title>A Consolidated Namespace for Network Applications, Developers, Administrators and Users</title>
<author initials="M." surname="Komu"></author>
<date year="2012" month="December" />
</front>
<seriesInfo name="Dissertation, Aalto University, Espoo, Finland" value="ISBN: 978-952-60-4904-5 (printed), ISBN: 978-952-60-4905-2 (electronic). " />
</reference>
<reference anchor="lindqvist-enterprise">
<front>
<title>Enterprise Network Packet Filtering for Mobile Cryptographic Identities</title>
<author initials="J." surname="Lindqvist"></author>
<author initials="E." surname="Vehmersalo"></author>
<author initials="J." surname="Manner"></author>
<author initials="M." surname="Komu"></author>
<date year="2010" month="January-March" />
</front>
<seriesInfo name="International Journal of Handheld Computing Research, 1 (1), 79-94," value="" />
</reference>
<reference anchor="aura-dos">
<front>
<title>DOS-resistant Authentication with Client Puzzles</title>
<author initials="T." surname="Aura"></author>
<author initials="P." surname="Nikander"></author>
<author initials="J." surname="Leiwo"></author>
<date year="2001" month="April" />
</front>
<seriesInfo name="8th International Workshop on Security Protocols, pages 170-177. Springer," value="" />
</reference>
<reference anchor="beal-dos">
<front>
<title>Deamplification of DoS Attacks via Puzzles</title>
<author initials="J." surname="Beal"></author>
<author initials="T." surname="Shephard"></author>
<date year="2004" month="October" />
</front>
<seriesInfo name="" value="" />
</reference>
<reference anchor="tritilanunt-dos">
<front>
<title>Examining the DoS Resistance of HIP</title>
<author initials="S." surname="Tritilanunt"></author>
<author initials="C." surname="Boyd"></author>
<author initials="E." surname="Foo"></author>
<author initials="J. M. G." surname="Nieto"></author>
<date year="2006" month="" />
</front>
<seriesInfo name="OTM Workshops (1), volume 4277 of Lecture Notes
in Computer Science, pages 616-625,Springer" value="" />
</reference>
<reference anchor="komu-mitigation">
<front>
<title>Mitigation of Unsolicited Traffic Across Domains with Host Identities and Puzzles</title>
<author initials="M." surname="Komu"></author>
<author initials="S." surname="Tarkoma"></author>
<author initials="A." surname="Lukyanenko"></author>
<date year="2010" month="October" />
</front>
<seriesInfo name="15th Nordic Conference on Secure IT Systems (NordSec 2010), Springer Lecture Notes in Computer Science, Volume 7127, pp. 33-48,"
value="ISBN: 978-3-642-27936-2" />
</reference>
<reference anchor="varjonen-split">
<front>
<title>Secure and Efficient IPv4/IPv6 Handovers Using Host-Based Identifier-Location Split</title>
<author initials="S." surname="Varjonen"></author>
<author initials="M." surname="Komu"></author>
<author initials="A." surname="Gurtov"></author>
<date year="2010" month="" />
</front>
<seriesInfo name="Journal of Communications Software and Systems, 6(1), 2010," value="ISSN: 18456421" />
</reference>
<reference anchor="ylitalo-spinat">
<front>
<title>SPINAT: Integrating IPsec into overlay routing</title>
<author initials="J." surname="Ylitalo"></author>
<author initials="P." surname="Salmela"></author>
<author initials="H." surname="Tschofenig"></author>
<date year="2005" month="September" />
</front>
<seriesInfo name="Proceedings of the First International Conference on Security and Privacy for Emerging Areas in Communication Networks (SecureComm 2005). Athens, Greece. IEEE Computer Society, pages 315-326,"
value="ISBN: 0-7695-2369-2" />
</reference>
<reference anchor="shields-hip">
<front>
<title>The HIP protocol for hierarchical multicast routing</title>
<author initials="C." surname="Shields"></author>
<author initials="J. J." surname="Garcia-Luna-Aceves"></author>
<date year="1998" month="" />
</front>
<seriesInfo name="Proceedings of the seventeenth annual ACM symposium on Principles of distributed computing, pages 257-266. ACM, New York, NY, USA," value="ISBN: 0-89791-977-7, DOI: 10.1145/277697.277744" />
</reference>
<reference anchor="xueyong-hip">
<front>
<title>A Multicast Routing Algorithm Applied to HIP-Multicast Model</title>
<author initials="Z." surname="Xueyong"></author>
<author initials="D." surname="Zhiguo"></author>
<author initials="W." surname="Xinling"></author>
<date year="2011" month="" />
</front>
<seriesInfo name="Proceedings of the 2011 International Conference on Network Computing and Information Security - Volume 01 (NCIS '11), Vol. 1. IEEE Computer Society, Washington, DC, USA, pages 169-174,"
value ="DOI: 10.1109/NCIS.2011.42" />
</reference>
<reference anchor="amir-hip">
<front>
<title>Security and Trust of Public Key Cryptography for HIP and HIP Multicast</title>
<author initials="K. C." surname="Amir"></author>
<author initials="H." surname="Forsgren"></author>
<author initials="K." surname="Grahn"></author>
<author initials="T." surname="Karvi"></author>
<author initials="G." surname="Pulkkis"></author>
<date year="2013" month="" />
</front>
<seriesInfo name="International Journal of Dependable and Trustworthy Information Systems (IJDTIS), 2(3), 17-35,"
value="DOI: 10.4018/jdtis.2011070102" />
</reference>
<reference anchor="kovacshazi-host">
<front>
<title>Host Identity Specific Multicast</title>
<author initials="Z." surname="Kovacshazi"></author>
<author initials="R." surname="Vida"></author>
<date year="2007" month="" />
</front>
<seriesInfo name="International conference on Networking and Services (ICNS'06), IEEE Computer Society, Los Alamitos, CA, USA,"
value="http://doi.ieeecomputersociety.org/10.1109/ICNS.2007.66" />
</reference>
<reference anchor="xueyong-secure">
<front>
<title>A Secure Multicast Model for Peer-to-Peer and Access Networks Using the Host Identity Protocol</title>
<author initials="Z." surname="Xueyong"></author>
<author initials="J. W." surname="Atwood"></author>
<date year="2007" month="January" />
</front>
<seriesInfo name="Consumer Communications and Networking Conference. CCNC 2007. 4th IEEE, pages 1098,1102," value="DOI: 10.1109/CCNC.2007.221" />
</reference>
<reference anchor="sarela-bloom">
<front>
<title>BloomCasting: Security in Bloom filter based multicast</title>
<author initials="M." surname="Särelä"></author>
<author initials="C." surname="Esteve Rothenberg"></author>
<author initials="A." surname="Zahemszky"></author>
<author initials="P." surname="Nikander"></author>
<author initials="J." surname="Ott"></author>
<date year="2012" />
</front>
<seriesInfo name=""
value="" />
<seriesInfo name="Lecture Notes in Computer Science"
value="2012" />
<seriesInfo name="" value="" />
<seriesInfo name="pages" value="1-16" />
<seriesInfo name="" value="Springer Berlin Heidelberg" />
<format type=""
target="http://dx.doi.org/10.1007/978-3-642-27937-9_1" />
</reference>
<reference anchor="pham-leap">
<front>
<title>Security Analysis of Leap-of-Faith Protocols</title>
<author initials="V." surname="Pham"></author>
<author initials="T." surname="Aura"></author>
<date year="2011" month="September" />
</front>
<seriesInfo name=" Seventh ICST International Conference on Security and Privacy for Communication Networks," value="" />
</reference>
<reference anchor="karvonen-usable">
<front>
<title>Usable Security Management with Host Identity Protocol</title>
<author initials="K." surname="Karvonen"></author>
<author initials="M." surname="Komu"></author>
<author initials="A." surname="Gurtov"></author>
<date year="2009" month="" />
</front>
<seriesInfo name="7th ACS/IEEE International Conference on Computer Systems and Applications," value="(AICCSA-2009)" />
</reference>
<reference anchor="ylitalo-diss">
<front>
<title>Secure Mobility at Multiple Granularity Levels over Heterogeneous Datacom Networks</title>
<author initials="J." surname="Ylitalo"></author>
<date year="2008" month="" />
</front>
<seriesInfo name="Dissertation, Helsinki University of Technology, Espoo, Finland" value="ISBN 978-951-22-9531-9" />
</reference>
<reference anchor="xin-hip-lib">
<front>
<title>Host Identity Protocol Version 2.5</title>
<author initials="G." surname="Xin"></author>
<date year="2012" month="June" />
</front>
<seriesInfo name="Master's Thesis, Aalto University, Espoo, Finland," value="" />
</reference>
<reference anchor="schuetz-intermittent">
<front>
<title>Protocol enhancements for intermittently connected hosts</title>
<author initials="S." surname="Schütz"></author>
<author initials="L." surname="Eggert"></author>
<author initials="S." surname="Schmid"></author>
<author initials="M." surname="Brunner"></author>
<date year="2005" month="July" />
</front>
<seriesInfo name="SIGCOMM Comput. Commun. Rev., 35(3):5-18," value="" />
</reference>
<reference anchor="paine-hip">
<front>
<title>Beyond HIP: The End to Hacking As We Know It</title>
<author initials="R. H." surname="Paine"></author>
<date year="2009" month="" />
</front>
<seriesInfo name="BookSurge Publishing," value="ISBN: 1439256047, 9781439256046" />
</reference>
<reference anchor="leva-barriers">
<front>
<title>Adoption Barriers of Network-layer Protocols: the Case of Host Identity Protocol</title>
<author initials="A. K. T." surname="Levä"></author>
<author initials="M." surname="Komu"></author>
<author initials="S." surname="Luukkainen"></author>
<date year="2013" month="March" />
</front>
<seriesInfo name="The International Journal of Computer and Telecommunications Networking," value="ISSN: 1389-1286" />
</reference>
<reference anchor="heer-end-host">
<front>
<title>End-host Authentication and Authorization for Middleboxes based on a Cryptographic Namespace</title>
<author initials="T." surname="Heer"></author>
<author initials="R." surname="Hummen"></author>
<author initials="M." surname="Komu"></author>
<author initials="S." surname="Götz"></author>
<author initials="K." surname="Wehre"></author>
<date year="2009" month="" />
</front>
<seriesInfo name="ICC2009 Communication and Information Systems Security Symposium," value="" />
</reference>
<reference anchor="komu-cloud">
<front>
<title>Secure Networking for Virtual Machines in the Cloud</title>
<author initials="M." surname="Komu"></author>
<author initials="M." surname="Sethi"></author>
<author initials="R." surname="Mallavarapu"></author>
<author initials="H." surname="Oirola"></author>
<author initials="R." surname="Khan"></author>
<author initials="S." surname="Tarkoma"></author>
<date year="2012" month="September" />
</front>
<seriesInfo name="International Workshop on Power and QoS Aware Computing (PQoSCom2012), IEEE," value="ISBN: 978-1-4244-8567-3" />
</reference>
<reference anchor="zhang-revocation">
<front>
<title>Host Identifier Revocation in HIP</title>
<author initials="D." surname="Zhang"></author>
<author initials="D." surname="Kuptsov"></author>
<author initials="S." surname="Shen"></author>
<date year="2012" month="Mar" />
</front>
<seriesInfo name="IRTF Working draft" value="draft-irtf-hiprg-revocation-05"/>
</reference>
<reference anchor="urien-rfid-draft">
<front>
<title>HIP support for RFIDs</title>
<author initials="P." surname="Urien"></author>
<author initials="G." surname="Lee"></author>
<author initials="G." surname="Pujolle"></author>
<date year="2013" month="April" />
</front>
<seriesInfo name="IRTF Working draft" value="draft-irtf-hiprg-rfid-07"/>
</reference>
<reference anchor="hip-srtp">
<front>
<title>Using SRTP transport format with HIP</title>
<author initials="H." surname="Tschofenig"></author>
<author initials="F." surname="Muenz"></author>
<author initials="M." surname="Shanmugam"></author>
<date year="2005" month="October" />
</front>
<seriesInfo name="Working draft" value="draft-tschofenig-hiprg-hip-srtp-01"/>
</reference>
<reference anchor="henderson-vpls">
<front>
<title>HIP-based Virtual Private LAN Service (HIPLS)</title>
<author initials="T." surname="Henderson"></author>
<author initials="D." surname="Mattes"></author>
<date year="2013" month="Dec" />
</front>
<seriesInfo name="Working draft" value="draft-henderson-hip-vpls-07"/>
</reference>
<reference anchor="heer-midauth">
<front>
<title>End-Host Authentication for HIP Middleboxes</title>
<author initials="T." surname="Heer"></author>
<author initials="M." surname="Komu"></author>
<date year="2009" month="September" />
</front>
<seriesInfo name="Working draft" value="draft-heer-hip-middle-auth-02"/>
</reference>
<!--
<reference anchor="herborn-secure">
<front>
<title>"Secure Host Identity Delegation for Mobility," Communication Systems Software and Middleware</title>
<author initials="S." surname="Herborn"></author>
<author initials="A." surname="Huber"></author>
<author initials="R." surname="Boreli"></author>
<author initials="A." surname="Seneviratne"></author>
<date year="2007" month="January" />
</front>
<seriesInfo name="Communication Systems Software and Middleware. COMSWARE 2007. pages 1, 9," value="DOI: 10.1109/COMSWA.2007.382596" />
</reference>
<reference anchor="nikander-hip">
<front>
<title> Integrating security, mobility, and multi-homing in a HIP way</title>
<author initials="P." surname="Nikander"></author>
<author initials="J." surname="Ylitalo"></author>
<author initials="J." surname="Wall"></author>
<date year="2003" month="February" />
</front>
<seriesInfo name="Proceedings of the 10th Annual Network and Distributed System Security Symposium (NDSS 2003). San Diego, CA, USA. Internet Society, pages 87-99,"
value="ISBN 1-891562-16-9" />
</reference>
<reference anchor="caesar-routing">
<front>
<title>Rofl: routing on flat labels</title>
<author initials="M." surname="Caesar"></author>
<author initials="T." surname="Condie"></author>
<author initials="J." surname="Kannan"></author>
<author initials="K." surname="Lakshminarayanan"></author>
<author initials="I." surname="Stoica"></author>
<date year="2006" month="" />
</front>
<seriesInfo name="Proceedings of the 2006 conference on Appli-
cations, technologies, architectures, and protocols for computer communi-
cations, SIGCOMM '06, pages 363-374, ACM, New York, NY, USA, 2006," value="" />
</reference>
<reference anchor="saltzer-notes">
<front>
<title>Naming and Binding of Objects In Operating Systems</title>
<author initials="J." surname="Saltzer"></author>
<date year="1978" month="" />
</front>
<seriesInfo name="Lecture Notes in Computer Science, Vol. 60. Springer-Verlag," value="" />
</reference>
<reference anchor="saltzer-end">
<front>
<title>End-to-end Arguments in System Design</title>
<author initials="J. H." surname="Saltzer"></author>
<author initials="D. P." surname="Reed"></author>
<author initials="D. D." surname="Clark"></author>
<date year="1984" month="November" />
</front>
<seriesInfo name="ACM Trans. Comput. Syst., 2(4):277-288," value="" />
</reference>
<reference anchor="shoch-naming">
<front>
<title>Inter-Network Naming, Addressing, and Routing</title>
<author initials="J." surname="Shoch"></author>
<date year="1978" month="" />
</front>
<seriesInfo name="IEEE Proc. COMPCON, pages 72-79. IEEE," value="" />
</reference>
-->
</references>
</back>
</rfc>
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