draft-ietf-ippm-ipsec-01.txt   draft-ietf-ippm-ipsec-02.txt 
IPPM WG K. Pentikousis, Ed. IPPM WG K. Pentikousis, Ed.
Internet-Draft EICT Internet-Draft EICT
Intended status: Standards Track Y. Cui Intended status: Standards Track Y. Cui
Expires: April 24, 2014 E. Zhang Expires: August 18, 2014 E. Zhang
Huawei Technologies Huawei Technologies
October 21, 2013 February 14, 2014
Network Performance Measurement for IPsec Network Performance Measurement for IPsec
draft-ietf-ippm-ipsec-01 draft-ietf-ippm-ipsec-02
Abstract Abstract
IPsec is a mature technology with several interoperable The O/TWAMP security mechanism requires that endpoints (i.e. both the
implementations. Indeed, the use of IPsec tunnels is increasingly client and the server) possess a shared secret. Since the currently-
gaining popularity in several deployment scenarios, not the least in standardized O/TWAMP security mechanism only supports a pre-shared
what used to be solely areas of traditional telecommunication key mode, large scale deployment of O/TWAMP is hindered
protocols. Wider IPsec deployment calls for mechanisms and methods significantly. At the same time, recent trends point to wider IKEv2
that enable tunnel end-users, as well as operators, to measure one- deployment, which in turn calls for mechanisms and methods that
way and two-way network performance in a standardized manner. enable tunnel end-users, as well as operators, to measure one-way and
Unfortunately, however, standard IP performance measurement security two-way network performance in a standardized manner. This document
mechanisms cannot be readily used with IPsec. This document makes discusses the use of keys derived from an IKE SA as the shared key in
the case for employing IPsec to protect the One-way and Two-Way O/TWAMP. If the shared key can be derived from the IKE SA, O/TWAMP
Active Measurement Protocols (O/TWAMP) and proposes a method which can support cert-based key exchange, which would allow for more
combines IKEv2 and O/TWAMP as defined in RFC 4656 and RFC 5357, flexibility and efficiency. Such key derivation can also facilitate
respectively. This specification aims, on the one hand, to ensure automatic key management.
that O/TWAMP can be secured with the best mechanisms we have at our
disposal today while, on the other hand, it facilitates the
applicability of O/TWAMP to networks that have already deployed
IPsec.
Status of This Memo Status of This Memo
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This Internet-Draft will expire on April 24, 2014. This Internet-Draft will expire on August 18, 2014.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. O/TWAMP Security . . . . . . . . . . . . . . . . . . . . . . 3
3.1. O/TWAMP-Control Security . . . . . . . . . . . . . . . . 5 3.1. O/TWAMP-Control Security . . . . . . . . . . . . . . . . 4
3.2. O/TWAMP-Test Security . . . . . . . . . . . . . . . . . . 6 3.2. O/TWAMP-Test Security . . . . . . . . . . . . . . . . . . 5
3.3. O/TWAMP Security Root . . . . . . . . . . . . . . . . . . 7 3.3. O/TWAMP Security Root . . . . . . . . . . . . . . . . . . 6
3.4. O/TWAMP and IPsec . . . . . . . . . . . . . . . . . . . . 7 4. O/TWAMP for IPsec Networks . . . . . . . . . . . . . . . . . 6
4. O/TWAMP for IPsec Networks . . . . . . . . . . . . . . . . . 8 4.1. Shared Key Derivation . . . . . . . . . . . . . . . . . . 6
4.1. Shared Key Derivation . . . . . . . . . . . . . . . . . . 8 4.2. Server Greeting Message Update . . . . . . . . . . . . . 7
4.2. Server Greeting Message Update . . . . . . . . . . . . . 9 4.3. Set-Up-Response Update . . . . . . . . . . . . . . . . . 9
4.3. Session Key Derivation . . . . . . . . . . . . . . . . . 11 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10
4.3.1. Alternative 1 . . . . . . . . . . . . . . . . . . . . 12 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
4.3.2. Alternative 2 . . . . . . . . . . . . . . . . . . . . 14 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10
5. Security Considerations . . . . . . . . . . . . . . . . . . . 15 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 8.1. Normative References . . . . . . . . . . . . . . . . . . 10
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16 8.2. Informative References . . . . . . . . . . . . . . . . . 11
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
8.1. Normative References . . . . . . . . . . . . . . . . . . 16
8.2. Informative References . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction 1. Introduction
The One-way Active Measurement Protocol (OWAMP) [RFC4656] and the The One-way Active Measurement Protocol (OWAMP) [RFC4656] and the
Two-Way Active Measurement Protocol (TWAMP) [RFC5357] can be used to Two-Way Active Measurement Protocol (TWAMP) [RFC5357] can be used to
measure network performance parameters, such as latency, bandwidth, measure network performance parameters, such as latency, bandwidth,
and packet loss by sending probe packets and monitoring their and packet loss by sending probe packets and monitoring their
experience in the network. In order to guarantee the accuracy of experience in the network. In order to guarantee the accuracy of
network measurement results, security aspects must be considered. network measurement results, security aspects must be considered.
Otherwise, attacks may occur and the authenticity of the measurement Otherwise, attacks may occur and the authenticity of the measurement
results may be violated. For example, if no protection is provided, results may be violated. For example, if no protection is provided,
an adversary in the middle may modify packet timestamps, thus an adversary in the middle may modify packet timestamps, thus
altering the measurement results. altering the measurement results.
Cryptographic security mechanisms, such as IPsec, have been The currently-standardized O/TWAMP security mechanism [RFC4656]
considered during the early stage of the specification of the two [RFC5357] requires that endpoints (i.e. both the client and the
active measurement protocols mentioned above. However, due to server) possess a shared secret. In today's network deployments,
several reasons, it was decided to avoid tying the development and however, the use of pre-shared keys may not be optimal. For example,
deployment of O/TWAMP to such security mechanisms. In practice, for in wireless infrastructure networks, certain network elements, which
many networks, the issues listed in [RFC4656], Sec. 6.6 with respect can be seen as the two endpoints from an O/TWAMP perspective, support
to IPsec are still valid. However, we expect that in the near future certificate-based security. This is the case when one wants to
IPsec will be deployed in many more hosts and networks than today. measure IP performance between an eNB and SeGW, for instance. Since
For example, IPsec tunnels may be used to secure wireless channels. the currently standardized O/TWAMP security mechanism only supports
In this case, what we are interested in is measuring network pre-shared key mode, large scale deployment of O/TWAMP is hindered
performance specifically for the traffic carried by the secured significantly. Furthermore, deployment and management of "shared
tunnel, not over the wireless channel in general. This document secrets" for massive equipment installation consumes a tremendous
makes the case that O/TWAMP should be cognizant when IPsec and other amount of effort and is prone to human error.
security mechanisms are in place and can be leveraged upon. In other
words, it is now time to specify how O/TWAMP is used in a network
environment where IPsec is already deployed. We expect that in such
an environment, measuring IP performance over IPsec tunnels with O/
TWAMP is an important tool for operators.
For example, when considering the use of O/TWAMP in networks with With IKEv2 widely used, using keys derived from IKE SA as shared key
IPsec deployed, we can take advantage of the IPsec key exchange can be considered as a viable alternative. In mobile
protocol [RFC5996]. In particular, we note that it is not necessary telecommunication networks, the deployment rate of IPsec exceeds 95%
to use distinct keys in OWAMP-Control and OWAMP-Test layers. One key with respect to the LTE serving network. In older-technology
for encryption and another for authentication is sufficient for both cellular networks, such as UMTS and GSM, IPsec use penetration is
Control and Test layers. This obviates the need to generate two keys lower, but still quite significant. If the shared key can be derived
for each layer and reduces the complexity of O/TWAMP protocols in an from the IKE SA, O/TWAMP can support cert-based key exchange and make
IPsec environment. This observation comes from the fact that it more flexible in practice and more efficient. The use of IKEv2
separate session keys in the OWAMP-Control and OWAMP-Test layers were also makes it easier to extend automatic key management. In general,
designed for preventing reflection attacks when employing the current O/TWAMP measurement packets can be transmitted inside the IPsec
mechanism. Once IPsec is employed, such a potential threat is tunnel, as it occurs with typical user traffic, or transmitted
alleviated. outside the IPsec tunnel. This may depend on the operator's policy
and is orthogonal to the mechanism described in this document.
The remainder of this document is organized as follows. Section 3 The remainder of this document is organized as follows. Section 3
motivates this work by revisiting the arguments made in [RFC4656] summarizes O/TWAMP protocol operation with respect to security.
against the use of IPsec; this section also summarizes protocol Section 4 presents a method of binding O/TWAMP and IKEv2 for network
operation with respect to security. Section 4 presents a method of measurements between the client and the server which both support
binding O/TWAMP and IKEv2 for network measurements between a sender IKEv2. Finally, Section 5 discusses the security considerations
and a receiver which both support IPsec. Finally, Section 5 arising from the proposed mechanisms.
discusses the security considerations arising from the proposed
mechanisms.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. Motivation 3. O/TWAMP Security
In order to motivate the solutions proposed in this document, let us
first revisit Section 6.6 of [RFC4656]. As we explain below, the
reasons originally listed therein may not apply in many cases today.
RFC 4656 opts against using IPsec and instead favors the use of "a
simple cryptographic protocol (based on a block cipher in CBC mode)".
The first argument justifying this decision in [RFC4656] is that
partial authentication in OWAMP authentication mode is not possible
with IPsec. IPsec indeed cannot authenticate only a part of a
packet. However, in an environment where IPsec is already deployed
and actively used, partial authentication for OWAMP contradicts the
operational reasons dictating the use of IPsec. It also increases
the operational complexity of OWAMP (and TWAMP) in networks where
IPsec is actively used and may in practice limit its applicability.
The second argument made is the need to keep separate deployment
paths between OWAMP and IPsec. In several currently deployed types
of networks IPsec is widely used to protect the data and signaling
planes. For example, in mobile telecommunication networks, the
deployment rate of IPsec exceeds 95% with respect to the LTE serving
network. In older technology cellular networks, such as UMTS and
GSM, IPsec use penetration is lower, but still quite significant.
Additionally, there is a great number of IPsec-based VPN applications
which are widely used in business applications to provide end-to-end
security over, for instance, publicly open or otherwise untrusted
IEEE 802.11 wireless LANs. At the same time, many IETF-standardized
protocols make use of IPsec/IKE, including MIPv4/v6, HIP, SCTP, BGP,
NAT and SIP, just to name a few.
The third argument in [RFC4656] is that, effectively, the adoption of
IPsec in OWAMP may be problematic for "lightweight embedded devices."
However, since the publication of RFC 4656, a large number of
limited-resource and low-cost hardware, such as Ethernet switches,
DSL modems, set-top boxes and other such devices come with support
for IPsec "out of the box". Therefore concerns about implementation,
although likely valid a decade ago, are not well founded today.
Finally, everyday use of IPsec applications by field technicians and
good understanding of the IPsec API by many programmers should no
longer be a reason for concern. On the contrary: By now, IPsec open
source code is available for anyone who wants to use it. Therefore,
although IPsec does need a certain level of expertise to deal with
it, in practice, most competent technical personnel and programmers
have no problems using it on a daily basis.
OWAMP and TWAMP actually consist of two inter-related protocols: O/
TWAMP-Control and O/TWAMP-Test. With respect to TWAMP, since "TWAMP
and OWAMP use the same protocol for establishment of Control and Test
procedures" [RFC5357] (Section 6), IPsec is also not considered. O/
TWAMP-Control is used to initiate, start, and stop test sessions and
to fetch their results, whereas O/TWAMP-Test is used to exchange test
packets between two measurement nodes.
In the remainder of this section we review security for O/TWAMP- Security for O/TWAMP-Control and O/TWAMP-Test are reviewed separately
Control and O/TWAMP-Test separately and then make the case for using in this section.
them over IPsec.
3.1. O/TWAMP-Control Security 3.1. O/TWAMP-Control Security
O/TWAMP uses a simple cryptographic protocol which relies on O/TWAMP uses a simple cryptographic protocol which relies on
o AES in Cipher Block Chaining (AES-CBC) for confidentiality o AES in Cipher Block Chaining (AES-CBC) for confidentiality
o HMAC-SHA1 truncated to 128 bits for message authentication o HMAC-SHA1 truncated to 128 bits for message authentication
Three modes of operation are supported: unauthenticated, Three modes of operation are supported in the OWAMP-Control protocol:
authenticated, and encrypted. The authenticated and encrypted modes unauthenticated, authenticated, and encrypted. Besides the above
three modes supported, the TWAMP-Control protocol also supports an
additional mode: mixed mode, i.e. the TWAMP-Control protocol operates
in encrypted mode while TWAMP-Test protocol operates in
unauthenticated mode. The authenticated, encrypted and mixed modes
require that endpoints possess a shared secret, typically a require that endpoints possess a shared secret, typically a
passphrase. The secret key is derived from the passphrase using a passphrase. The secret key is derived from the passphrase using a
password-based key derivation function PBKDF2 (PKCS#5) [RFC2898]. password-based key derivation function PBKDF2 (PKCS#5) [RFC2898].
In the unauthenticated mode, the security parameters are left unused. In the unauthenticated mode, the security parameters are left unused.
In the authenticated and encrypted modes, security parameters are In the authenticated, encrypted and mixed modes, the security
negotiated during the control connection establishment. parameters are negotiated during the control connection
establishment.
Figure 1 illustrates the initiation stage of the O/TWAMP-Control Figure 1 illustrates the initiation stage of the O/TWAMP-Control
protocol between a client and the server. In short, the client opens protocol between a client and the server. In short, the client opens
a TCP connection to the server in order to be able to send OWAMP- a TCP connection to the server in order to be able to send O/TWAMP-
Control commands. The server responds with a Server Greeting, which Control commands. The server responds with a Server Greeting, which
contains the Modes, Challenge, Salt, Count, and MBZ fields (see contains the Modes, Challenge, Salt, Count, and MBZ fields (see
Section 3.1 of [RFC4656]). If the client-preferred mode is Section 3.1 of [RFC4656]). If the client-preferred mode is
available, the client responds with a Set-Up-Response message, available, the client responds with a Set-Up- Response message,
wherein the selected Mode, as well as the KeyID, Token and Client IV wherein the selected Mode, as well as the KeyID, Token and Client IV
are included. The Token is the concatenation of a 16-octet are included. The Token is the concatenation of a 16-octet
Challenge, a 16-octet AES Session-key used for encryption, and a Challenge, a 16-octet AES Session-key used for encryption, and a
32-octet HMAC-SHA1 Session-key used for authentication. The Token is 32-octet HMAC-SHA1 Session-key used for authentication. The Token is
encrypted using AES-CBC. encrypted using AES-CBC.
+--------+ +--------+ +--------+ +--------+
| Client | | Server | | Client | | Server |
+--------+ +--------+ +--------+ +--------+
| | | |
skipping to change at page 6, line 18 skipping to change at page 5, line 21
|<---- Greeting message ----| |<---- Greeting message ----|
| | | |
|----- Set-Up-Response ---->| |----- Set-Up-Response ---->|
| | | |
|<---- Server-Start --------| |<---- Server-Start --------|
| | | |
Figure 1: Initiation of O/TWAMP-Control Figure 1: Initiation of O/TWAMP-Control
Encryption uses a key derived from the shared secret associated with Encryption uses a key derived from the shared secret associated with
KeyID. In the authenticated and encrypted modes, all further KeyID. In the authenticated, encrypted and mixed modes, all further
communication is encrypted using the AES Session-key and communication is encrypted using the AES Session-key and
authenticated with the HMAC Session-key. The client encrypts authenticated with the HMAC Session-key. After receiving Set-Up-
everything it transmits through the just-established O/TWAMP-Control Response the server responds with a Server-Start message containing
connection using stream encryption with Client-IV as the IV. Server-IV. The client encrypts everything it transmits through the
Correspondingly, the server encrypts its side of the connection using just-established O/TWAMP-Control connection using stream encryption
Server-IV as the IV. The IVs themselves are transmitted in with Client- IV as the IV. Correspondingly, the server encrypts its
cleartext. Encryption starts with the block immediately following side of the connection using Server-IV as the IV. The IVs themselves
that containing the IV. are transmitted in cleartext. Encryption starts with the block
immediately following that containing the IV.
The AES Session-key and HMAC Session-key are generated randomly by The AES Session-key and HMAC Session-key are generated randomly by
the client. The HMAC Session-key is communicated along with the AES the client. The HMAC Session-key is communicated along with the AES
Session-key during O/TWAMP-Control connection setup. The HMAC Session-key during O/TWAMP-Control connection setup. The HMAC
Session-key is derived independently of the AES Session-key. Session-key is derived independently of the AES Session-key.
3.2. O/TWAMP-Test Security 3.2. O/TWAMP-Test Security
The O/TWAMP-Test protocol runs over UDP, using the sender and The O/TWAMP-Test protocol runs over UDP, using the client and server
receiver IP and port numbers that were negotiated during the Request- IP and port numbers that were negotiated during the Request-Session
Session exchange. O/TWAMP-Test has the same three modes as with O/ exchange. O/TWAMP- Test has the same mode with O/TWAMP-Control and
TWAMP-Control (unauthenticated, authenticated, and encrypted) and all all O/TWAMP-Test sessions inherit the corresponding O/TWAMP-Control
O/TWAMP-Test sessions inherit the corresponding O/TWAMP-Control session mode except when operating in mixed mode.
session mode.
The O/TWAMP-Test packet format is the same in authenticated and The O/TWAMP-Test packet format is the same in authenticated and
encrypted modes. The encryption and authentication operations are, encrypted modes. The encryption and authentication operations are,
however, different. Similarly with the respective O/TWAMP-Control however, different. Similarly with the respective O/TWAMP-Control
session, each O/TWAMP-Test session has two keys: an AES Session-key session, each O/TWAMP-Test session has two keys: an AES Session-key
and an HMAC Session-key. However, there is a difference in how the and an HMAC Session-key. However, there is a difference in how the
keys are obtained: keys are obtained:
O/TWAMP-Control: the keys are generated by the client and O/TWAMP-Control: the keys are generated by the client and
communicated to the server during the control connection communicated to the server during the control connection
establishment with the Set-Up-Response message (as part of establishment with the Set-Up-Response message (as part of
the Token). the Token).
O/TWAMP-Test: the keys are derived from the O/TWAMP-Control keys and O/TWAMP-Test: the keys are derived from the O/TWAMP-Control keys and
the session identifier (SID), which serve as inputs of the the session identifier (SID), which serve as inputs of the
key derivation function (KDF). The O/TWAMP-Test AES Session- key derivation function (KDF). The O/TWAMP-Test AES Session-
key is generated using the O/TWAMP-Control AES Session-key, key is generated using the O/TWAMP- Control AES Session-key,
with the 16-octet session identifier (SID), for encrypting with the 16-octet session identifier (SID), for encrypting
and decrypting the packets of the particular O/TWAMP-Test and decrypting the packets of the particular O/TWAMP-Test
session. The O/TWAMP-Test HMAC Session-key is generated session. The O/TWAMP-Test HMAC Session-key is generated
using the O/TWAMP-Control HMAC Session-key, with the 16-octet using the O/TWAMP-Control HMAC Session-key, with the 16-octet
session identifier (SID), for authenticating the packets of session identifier (SID), for authenticating the packets of
the particular O/TWAMP-Test session. the particular O/TWAMP-Test session.
3.3. O/TWAMP Security Root 3.3. O/TWAMP Security Root
As discussed above, the AES Session-key and HMAC Session-key used in As discussed above, the AES Session-key and HMAC Session-key used in
the O/TWAMP-Test protocol are derived from the AES Session-key and the O/TWAMP-Test protocol are derived from the AES Session-key and
HMAC Session-key which are used in O/TWAMP-Control protocol. The AES HMAC Session-key which are used in O/TWAMP-Control protocol. The AES
Session-key and HMAC Session-key used in the O/TWAMP-Control protocol Session-key and HMAC Session-key used in the O/TWAMP-Control protocol
are generated randomly by the client, and encrypted with the shared are generated randomly by the client, and encrypted with the shared
secret associated with KeyID. Therefore, the security root is the secret associated with KeyID. Therefore, the security root is the
shared secret key. Thus, for large deployments, key provision and shared secret key. Thus, for large deployments, key provision and
management may become overly complicated. Comparatively, a management may become overly complicated. Comparatively, a
certificate-based approach using IKEv2/IPsec can automatically manage certificate-based approach using IKEv2 can automatically manage the
the security root and solve this problem, as we explain in Section 4. security root and solve this problem, as we explain in Section 4.
3.4. O/TWAMP and IPsec
According to [RFC4656] the "deployment paths of IPsec and OWAMP could
be separate if OWAMP does not depend on IPsec." However, the problem
that arises in practice is that the security mechanism of O/TWAMP and
IPsec cannot coexist at the same time without adding overhead or
increasing complexity.
IPsec provides confidentiality and data integrity to IP datagrams.
Distinct protocols are provided: Authentication Header (AH),
Encapsulating Security Payload (ESP) and Internet Key Exchange (IKE
v1/v2). AH provides only integrity protection, while ESP can also
provide encryption. IKE is used for dynamical key negotiation and
automatic key management.
When sender and receiver implement O/TWAMP over IPsec, they need to
agree on a shared secret key during the IPsec tunnel establishment.
Subsequently, all IP packets sent by the sender are protected. If
the AH protocol is used, IP packets are transmitted in plaintext.
The authentication part covers the entire packet. So all test
information, such as UDP port number, and the test results will be
visible to any attacker, which can intercept these test packets, and
introduce errors or forge packets that may be injected during the
transmission. In order to avoid this attack, the receiver must
validate the integrity of these packets with the negotiated secret
key. If ESP is used, IP packets are encrypted, and hence only the
receiver can use the IPsec secret key to decrypt the IP packet, and
obtain the test data in order to assess the IP network performance
based on the measurements. Both the sender and receiver must support
IPsec to generate the security secret key of IPsec.
Currently, after the test packets are received by the receiver, it
cannot execute active measurement over IPsec. That is because the
receiver knows only the shared secret key but not the IPsec key,
while the test packets are protected by the IPsec key ultimately.
Therefore, it needs to be considered how to measure IP network
performance in an IPsec tunnel with O/TWAMP. Without this
functionality, the use of OWAMP and TWAMP over IPsec is hindered.
Of course, backward compatibility should be considered as well. That
is, the intrinsic security method based on shared key as specified in
the O/TWAMP standards can also still be suitable for other network
settings. There should be no impact on the current security
mechanisms defined in O/TWAMP for other use cases. This document
describes possible solutions to this problem which take advantage of
the secret key derived by IPsec, in order to provision the key needed
for active network measurements based on [RFC4656] and [RFC5357].
4. O/TWAMP for IPsec Networks 4. O/TWAMP for IPsec Networks
This section presents a method of binding O/TWAMP and IKEv2 for This section presents a method of binding O/TWAMP and IKEv2 for
network measurements between a client and a server which both support network measurements between a client and a server which both support
IPsec. In short, the shared key used for securing O/TWAMP traffic is IPsec. In short, the shared key used for securing O/TWAMP traffic is
derived using IKEv2 [RFC5996]. derived using IKEv2 [RFC5996].
4.1. Shared Key Derivation 4.1. Shared Key Derivation
If the AH protocol is used, the IP packets are transmitted in In the authenticated, encrypted and mixed modes, the shared secret
plaintext, but all O/TWAMP traffic is integrity-protected by IPsec. key can be derived from the IKEv2 Security Association (SA). Note
Therefore, even if the peers choose to opt for the unauthenticated that we explicitly opt to derive the shared secret key from the IKE
mode, IPsec integrity protection is extended to O/TWAMP. In the SA, rather than the child SA, since the use case whereby an IKE SA
authenticated and encrypted modes, the shared secret can be derived can be created without generating any child SA is possible [RFC6023].
from the IKEv2 Security Association (SA), or IPsec SA.
If the shared secret key is derived from the IKEv2 SA, SKEYSEED must If the shared secret key is derived from the IKE SA, SKEYSEED must be
be generated firstly. SKEYSEED and its derivatives are computed as generated first. SKEYSEED and its derivatives are computed as per
per [RFC5996], where prf is a pseudorandom function: [RFC5996], where prf is a pseudorandom function:
SKEYSEED = prf( Ni | Nr, g^ir ) SKEYSEED = prf( Ni | Nr, g^ir )
Ni and Nr are, respectively, the initiator and responder nonces, Ni and Nr are, respectively, the initiator and responder nonces,
which are negotiated during the initial exchange (see Section 1.2 of which are negotiated during the initial exchange (see Section 1.2 of
[RFC5996]). g^ir is the shared secret from the ephemeral Diffie- [RFC5996]). g^ir is the shared secret from the ephemeral Diffie-
Hellman exchange and is represented as a string of octets. Note that Hellman exchange and is represented as a string of octets.
this SKEYSEED can be used as the O/TWAMP shared secret key directly.
Alternatively, the shared secret key can be generated as follows:
Shared secret key = PRF{ SKEYSEED, Session ID }
wherein the Session ID is the O/TWAMP-Test SID.
If the shared secret key is derived from the IPsec SA, instead, the
shared secret key can be equal to KEYMAT, wherein
KEYMAT = prf+( SK_d, Ni | Nr )
The term "prf+" stands for a function that outputs a pseudorandom The shared secret key can be generated as follows:
stream based on the inputs to a prf, while SK_d is defined in
[RFC5996] (Sections 2.13 and 1.2, respectively). The shared secret
key can alternatively be generated as follows:
Shared secret key = PRF{ KEYMAT, Session ID } Shared secret key = PRF{ SKEYSEED, "IPPM" }
wherein the session ID is is the O/TWAMP-Test SID. The shared secret key is derived in the IPsec layer. Thus, the IPsec
keying material is not be exposed to the O/TWAMP client. Note that
the interaction between the O/TWAMP and IPsec implementations is
outside the scope of this document, which focuses on the interaction
between the O/TWAMP client and server. Of course, extracting the
shared secret key from the IPsec layer can depend on the
implementation. One possible way could be the following: at the
client side, the IPSec layer can perform a lookup in the Security
Association Database (SAD) using the IP address of the server and
thus match the corresponding IKE SA. At the server side, the IPSec
layer can look up the corresponding IKE SA by using the SPIs sent by
the client, and therefore extract the shared secret key.
If rekeying for the IKE SA and IPsec SA occurs, the corresponding key If rekeying for the IKE SA or deletion of the IKE SA occurs, the
of the SA is updated. Generally, ESP and AH SAs always exist in corresponding shared secret key generated from the SA can continue to
pairs, with one SA in each direction. If the SA is deleted, the key be used until the lifetime of the shared secret key expires.
generated from the IKE SA or IPsec SA should also be updated.
4.2. Server Greeting Message Update 4.2. Server Greeting Message Update
As discussed above, a binding association between the key generated To achieve a binding association between the key generated from IKE
from IPsec and the O/TWAMP shared secret key needs to be considered. and the O/TWAMP shared secret key, Server Greeting Message should be
The Security Association (SA) can be identified by the Security updated as in Figure 2.
Parameter Index (SPI) and protocol uniquely for a given sender and
receiver pair. Therefore, these parameters should be agreed upon
during the initiation stage of O/TWAMP-Control. At the stage that
the sender and receiver negotiate the integrity key, the IPsec
protocol and SPI MUST be checked. Only if the two parameters are
matched with the IPsec information, MUST the O/TWAMP connection be
established.
The Security Parameter Index (SPI) and protocol type (see [RFC4301]
[RFC5996]) will need to be included in the Server Greeting of the O/
TWAMP-Control protocol depicted in Figure 1. After the client
receives the greeting, it MUST close the connection if it receives a
greeting with an erroneous SPI and protocol value (Figure 2).
Otherwise, the client SHOULD generate the shared secret key as
discussed in Section 4.1 and respond with the server-expected Set-Up-
Response message.
The Modes field in Figure 2 will need to allow for support of key
derivation as discussed in Section 4.1. As such, pending discussion
in the IPPM WG, Modes value 8 MUST be supported by compatible
implementations, indicating support for IPsec. Server
implementations compatible with this document MUST set the first 28
bits of the Modes field to zero. A client compatible with this
specification MUST ignore the first 28 bits of the Modes field. For
backward compatibility, the server is obviously allowed to indicate
support for the Modes defined in [RFC4656]
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol | | |
|+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Unused (12 octets) |
| SPIi | | |
|+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SPIr |
|+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Modes | | Modes |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Challenge (16 octets) | | Challenge (16 octets) |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Salt (16 octets) | | Salt (16 octets) |
skipping to change at page 11, line 5 skipping to change at page 8, line 33
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Count (4 octets) | | Count (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| MBZ (12 octets) | | MBZ (12 octets) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Server Greeting format Figure 2: Server Greeting format
A compatible O/TWAMP client implementation would then interpret the The Modes field in Figure 2 will need to allow for support of key
originally unused 12 bits of the Server Greeting (see sec. 3.1 of derivation as discussed in Section 4.1. As such, pending discussion
[RFC4656]) as follows: The first 4 octets of the Server Greeting in the IPPM WG, Modes value 8 extension MUST be supported by
message indicate the protocol type, while the following 8 octets implementations compatible with this document, indicating support for
indicate the initiator (SPIi) and responder (SPIr) SPIs as deriving shared key from IKE SA. Modes value 16 indicates
illustrated in Figure 2. Note that in this case, the remaining authenticated mode; Modes value 32 indicates encrypted mode; and
fields of the Server Greeting message remain as per [RFC4656]. Modes value 64 indicates mixed mode over IKEv2.
EDITOR'S NOTE:
We expect that this implementation option would pose the least
backwards compatibility problems to existing O/TWAMP clients.
Robust client implementations of [RFC4656] would disregard that
the 29th Modes bit in the Server Greeting is set, and should
ignore the information contained in the newly defined fields
(Protocol, SPIi, SPIr). If the server supports other Modes, as
one would assume, the client would then indicate any of the
Modes defined in [RFC4656] and effectively indicate that it
does not support the IPsec mode. At this point, the Server
would need to use the Modes defined in [RFC4656] only.
When using ESP, all IP packets are encrypted, and therefore only the
receiver can use the IPsec key to decrypt the IP active measurement
packets. In this case, the IPsec tunnel between the sender and
receiver provides additional security: even if the peers choose the
unauthenticated mode, IPsec encryption and integrity protection is
provided to O/TWAMP. If the sender and receiver decide to use the
authenticated or encrypted mode, the shared secret can also be
derived from IKE SA or IPsec SA. The method for key generation and
binding association is the same discussed above for the AH protocol
mode.
There is an encryption-only configuration in ESP, though this is not
recommended due to its limitations. Since it does not produce
integrity key in this case, either encryption-only ESP should be
prohibited for O/TWAMP, or a decryption failure should be
distinguished due to possible integrity attack.
4.3. Session Key Derivation
Section 4.1 described a method for deriving the shared key for O/
TWAMP by capitalizing on IPsec. This is a step forward in terms of
facilitating O/TWAMP deployment at scale in IPsec networks as it
allows for greater and secure automation of standardized network
performance measurements. We note, however, that the O/TWAMP
protocol uses distinct encryption and integrity keys for O/TWAMP-
Control and O/TWAMP-Test. Consequently, four keys are generated to
protect O/TWAMP-Control and O/TWAMP-Test messages.
In fact, once IPsec is employed, one key for encryption and another
for authentication is sufficient for both the Control and Test
protocols. Therefore, in an IPsec environment we can further reduce
the operational complexity of O/TWAMP protocols in a straightforward
manner, as discussed below.
EDITOR'S NOTE:
We expect that both session key derivation proposals and
optimization alternatives will be discussed in the IPPM working
group and we are looking forward to community comments and
feedback.
4.3.1. Alternative 1
If an IPsec SA is established between the server and the client, or
both server and client support IPsec, the root key for O/TWAMP-based
active network measurements can be derived from the IKE or IPsec SA.
If the root key that will be used in O/TWAMP network performance
measurements is derived from the IKE SA, SKEYSEED must be generated
first. SKEYSEED and its derivatives are computed as per [RFC5996].
SKEYSEED can be used as the root key of O/TWAMP directly; then the
root key of O/TWAMP is equal to SKEYSEED. If the root key of O/TWAMP
is derived from the IPsec SA, the shared secret key can be equal to
KEYMAT. KEYMAT and its derivatives are computed as per usual
[RFC5996].
Then, the session keys for encryption and authentication can be
derived from the root key of O/TWAMP, wherein:
Session key for enc = PRF{ root key of O/TWAMP, "O/TWAMP enc" }
Session key for auth = PRF{ root key of O/TWAMP, "O/TWAMP auth" } Authenticated mode over IKEv2 means that the client and server
operate in authenticated mode with the shared secret key derived from
IKE SA. Encrypted mode over IKEv2 means that the client and server
operate in encrypted mode with the shared secret key derived from IKE
SA. Mixed mode over IKEv2 means that the client and server operate
in encrypted mode for the O/TWAMP-Control protocol while operating in
unauthenticated mode for the O/TWAMP-Test protocol with shared secret
key derived from IKE SA.
The former can provide encryption protection for O/TWAMP-Control and Server implementations compatible with this document MUST set the
O/TWAMP-Test messages, while the latter can provide integrity first 25 bits of the Modes field to zero. A client compatible with
protection. this specification MUST ignore the first 25 bits of the Modes field.
Note that there are cases where rekeying the IKE SA and IPsec SA is For backward compatibility, the server is obviously allowed to
necessary, and after which the corresponding key of SA is updated. indicate support for the Modes defined in [RFC4656]
If the SA is deleted, the O/TWAMP shared key generated from the IKE
SA or IPsec SA should also be updated.
EDITOR'S NOTE: The choice of this set of Modes values poses the least backwards
compatibility problems to existing O/TWAMP clients. Robust client
implementations of [RFC4656] would disregard that the first 29 Modes
bits in the Server Greeting is set. If the server supports other
Modes, as one would assume, the client would then indicate any of the
Modes defined in [RFC4656] and effectively indicate that it does not
support key derivation from IKE. At this point, the Server would
need to use the Modes defined in [RFC4656] only.
In addition to optimizing session key derivation, we can also 4.3. Set-Up-Response Update
reduce the verbosity of the Server Greeting and Set-Up-Response
messages, as explained below. Note, however, that such O/TWAMP
message simplification poses backward compatibility challenges,
which should be discussed in the IPPM WG.
In this optimization, the O/TWAMP-Control message exchange flow The Set-Up-Response Message should be updated as in Figure 3.
remains as per Figure 1. However, the optimized Server Greeting
(Figure 3) can do without the Salt and Count parameters (cf. Figure
2) since the root key of O/TWAMP is derived from IKE SA or IPsec SA.
O/TWAMP security can rely on IPsec and the SPI can uniquely identify
the IPsec SA from which the root key was derived from.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol | | Mode |
|+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SPIi |
|+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SPIr |
|+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Modes |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Challenge (16 octets) | | Key ID (80 octets) |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| MBZ (12 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Optimized Server Greeting format
The format of the Set-Up-Response is illustrated in Figure 4. The
Token carried in the Set-Up-Response is calculated as follows:
Token = Enc_root-key( Challenge )
where Challenge is the value received earlier in the Server Greeting
(Figure 3)
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mode |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Token (16 octets) | | Token (16 octets) |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| Client-IV (12 octets) | | Client-IV (12 octets) |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Set-Up-Response in Alternative 1 Figure 3: Set-Up-Response Message
If the server authenticates the token successfully, then the O/TWAMP-
Control message exchange flow can continue.
4.3.2. Alternative 2
Another way for optimizing the shared key use is to set the O/TWAMP
session keys equal to the keys of the IPsec SA directly, i.e:
Session key for enc = encryption key of the IPsec SA
Session key for auth = integrity key of the IPsec SA
The former session key can provide encryption protection for O/TWAMP-
Control and O/TWAMP-Test messages, while the latter can provide
integrity protection. The point made in the previous subsection
about rekeying the IPsec SA applies here too.
EDITOR'S NOTE:
As noted in the previous subsection, here too we can reduce the
verbosity of the Server Greeting and Set-Up-Response messages
even further, as explained below. Note, however, that such O/
TWAMP message simplification poses backward compatibility
challenges, which should be discussed in the IPPM WG.
The O/TWAMP control message exchange flow remains the same (i.e. as
per Figure 1), while the Server Greeting format is illustrated in
Figure 5. The Challenge, Salt, and Count parameters can be
eliminated since the session keys of O/TWAMP are equal to the keys of
an IPsec SA directly. SPI can identify the IPsec SA where the
session keys derived from. The similarly optimized Set-Up-Response
message is illustrated in Figure 6.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol |
|+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SPIi |
|+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SPIr |
|+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Modes |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| MBZ (12 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Optimized Server Greeting format The Security Parameter Index (SPI)(see [RFC4301] [RFC5996]) can
uniquely identify the Security Association (SA). If the client
supports the derivation of shared secret key from IKE SA, it will
choose the corresponding mode value and carry SPIi and SPIr in the
KeyID field. SPIi and SPIr are included in Key ID field of Set-Up-
Response Message to indicate the IKE SA which O/TWAMP shared secret
key derived from. The length of SPI is 4 octets. The first 4 octets
of Key ID field carries SPIi and the second 4 octets carries SPIr.
The rest bits of the Key ID field is set to zero.
0 1 2 3 A server which supports deriving shared secret from an IKE SA can
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 obtain the SPIi and SPIr from the first 8 octets and ignore the rest
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ octets of the Key ID field. Then, the client and the server can
| Mode | derive the shared secret key based on the mode value and SPI.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Client-IV (12 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Set-Up-Response in Alternative 2 If the server can not find the IKE SA corresponding to the SPIi and
SPIr, the Accept field of Server-Start message is extended to
indicate that. Accept value 6 can be used to indicate that server is
not willing to conduct further transactions in this OWAMP-Control
session since it can not find the corresponding IKE SA.
5. Security Considerations 5. Security Considerations
As the shared secret key is derived from IPsec, the key derivation As the shared secret key is derived from the IKE SA, the key
algorithm strength and limitations are as per [RFC5996]. The derivation algorithm strength and limitations are as per [RFC5996].
strength of a key derived from a Diffie-Hellman exchange using any of The strength of a key derived from a Diffie-Hellman exchange using
the groups defined here depends on the inherent strength of the any of the groups defined here depends on the inherent strength of
group, the size of the exponent used, and the entropy provided by the the group, the size of the exponent used, and the entropy provided by
random number generator employed. The strength of all keys and the random number generator employed. The strength of all keys and
implementation vulnerabilities, particularly Denial of Service (DoS) implementation vulnerabilities, particularly Denial of Service (DoS)
attacks are as defined in [RFC5996]. attacks are as defined in [RFC5996].
EDITOR'S NOTE: As a more general note, the IPPM community may want to revisit the
As a general note, the IPPM community may want to revisit the arguments listed in [RFC4656], Sec. 6.6. Other widely-used Internet
arguments listed in [RFC4656], Sec. 6.6. Other widely-used security mechanisms, such as TLS and DTLS, may also be considered for
Internet security mechanisms, such as TLS and DTLS, may also be future use over and above of what is already specified in [RFC4656]
considered for future use over and above of what is already [RFC5357].
specified in [RFC4656] [RFC5357].
6. IANA Considerations 6. IANA Considerations
IANA may need to allocate additional values for the Modes options
presented in this document. The values of the protocol field may IANA will need to allocate additional values for the Modes options
need to be assigned from the numbering space. presented in this document.
7. Acknowledgments 7. Acknowledgments
Emily Bi contributed to an earlier version of this document. Emily Bi contributed to an earlier version of this document.
We thank Eric Chen and Yakov Stein for their comments on this draft, We thank Eric Chen, Yakov Stein, and John Mattsson for their comments
and Al Morton for the discussion on related earlier work in IPPM WG. on this draft, and Al Morton for the discussion on related earlier
work in IPPM WG.
8. References 8. References
8.1. Normative References 8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. [RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
Zekauskas, "A One-way Active Measurement Protocol Zekauskas, "A One-way Active Measurement Protocol
skipping to change at page 16, line 42 skipping to change at page 11, line 25
5996, September 2010. 5996, September 2010.
8.2. Informative References 8.2. Informative References
[RFC2898] Kaliski, B., "PKCS #5: Password-Based Cryptography [RFC2898] Kaliski, B., "PKCS #5: Password-Based Cryptography
Specification Version 2.0", RFC 2898, September 2000. Specification Version 2.0", RFC 2898, September 2000.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the [RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005. Internet Protocol", RFC 4301, December 2005.
[RFC6023] Nir, Y., Tschofenig, H., Deng, H., and R. Singh, "A
Childless Initiation of the Internet Key Exchange Version
2 (IKEv2) Security Association (SA)", RFC 6023, October
2010.
Authors' Addresses Authors' Addresses
Kostas Pentikousis (editor) Kostas Pentikousis (editor)
EICT GmbH EICT GmbH
Torgauer Strasse 12-15 Torgauer Strasse 12-15
10829 Berlin 10829 Berlin
Germany Germany
Email: k.pentikousis@eict.de Email: k.pentikousis@eict.de
Yang Cui Yang Cui
Huawei Technologies Huawei Technologies
Otemachi First Square 1-5-1 Otemachi Otemachi First Square 1-5-1 Otemachi
Chiyoda-ku, Tokyo 100-0004 Chiyoda-ku, Tokyo 100-0004
Japan Japan
Email: cuiyang@huawei.com Email: cuiyang@huawei.com
Emma Zhang Emma Zhang
Huawei Technologies Huawei Technologies
Huawei Building, Q20, No.156, Rd. BeiQing Huawei Building, Q20, No.156, Rd. BeiQing
Haidian District , Beijing 100095 Haidian District , Beijing 100095
P. R. China P. R. China
Email: emma.zhanglijia@huawei.com Email: emma.zhanglijia@huawei.com
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