MSEC S. Fries
Internet-Draft H. Tschofenig
Expires: July 15, 2006 Siemens
January 11, 2006
Bootstrapping TESLA
draft-ietf-msec-bootstrapping-tesla-03.txt
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Copyright (C) The Internet Society (2006).
Abstract
TESLA, the Timed Efficient Stream Loss-tolerant Authentication
protocol is a protocol for providing source authentication in
multicast scenarios. TESLA is an efficient protocol with low
communication and computation overhead, which scales to large numbers
of receivers, and also tolerates packet loss. TESLA is based on
loose time synchronization between the sender and the receivers.
Source authentication is realized in TESLA by using Message
Authentication Code (MAC) chaining. The use of TESLA within the
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Secure Real-time Transport Protocol (SRTP) has been published
targeting multicast authentication in scenarios, where SRTP is
applied to protect the multimedia data. This solution assumes that
TESLA parameters are made available by out-of-band mechanisms.
This document specifies payloads for the Multimedia Internet Keying
(MIKEY) protocol for bootstrapping TESLA for source authentication of
secure group communications using SRTP. TESLA may be bootstrapped
using one of the MIKEY key management approaches, e.g., by using a
digitally signed MIKEY message sent via unicast, multicast or
broadcast.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. TESLA Parameter Overview . . . . . . . . . . . . . . . . . . . 4
4. Parameter encoding within MIKEY . . . . . . . . . . . . . . . 6
4.1. Security Policy payload (SP) . . . . . . . . . . . . . . . 6
4.2. TESLA policy . . . . . . . . . . . . . . . . . . . . . . . 7
4.3. Time synchronization . . . . . . . . . . . . . . . . . . . 9
4.4. Key data transport within MIKEY's General Extension
Payload . . . . . . . . . . . . . . . . . . . . . . . . . 10
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
5.1. Man-in-the-Middle (MitM) Attack . . . . . . . . . . . . . 11
5.2. Downgrading Attack . . . . . . . . . . . . . . . . . . . . 12
5.3. Denial of Service Attack . . . . . . . . . . . . . . . . . 12
5.4. Replay Attack . . . . . . . . . . . . . . . . . . . . . . 13
5.5. Traffic Analysis . . . . . . . . . . . . . . . . . . . . . 13
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8.1. Normative References . . . . . . . . . . . . . . . . . . . 16
8.2. Informative References . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
Intellectual Property and Copyright Statements . . . . . . . . . . 19
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1. Introduction
In many multicast, broadcast, and also unicast communication
scenarios it is necessary to guarantee that a recieved message has
been sent from a dedicated source and has not been altered while in
transfer. In unicast communication commonly a pairwise security
association exists, which enables the validation of message integrity
and data origin. The approach in group based communication is
different as here a key is normally shared between the members of a
group and thus this key may not be used for data origin
authentication. As in some applications a dedicated identification
of a sender is required, there exists the requirement to support data
origin authentication also in multicast scenarios. One of the
methods supporting this is TESLA [RFC4082]. TESLA provides source
authentication in multicast scenarios by using MAC chaining. It is
based on loose time synchronization between the sender and the
receivers.
[I-D.ietf-msec-srtp-tesla] describes extensions for SRTP [RFC3711] in
order to support TESLA [RFC4082] for source authentication in
multicast scenarios. SRTP needs dedicated cryptographic context
describing the security parameter and security policy per multimedia
session to be protected. This cryptographic context needs to be
enhanced with a set of TESLA parameters. It is necessary to provide
these parameters before the actual multicast session starts.
[I-D.ietf-msec-srtp-tesla] does not address the bootstrapping for
these parameters.
This document details bootstrapping of TESLA parameters in terms of
parameter distribution for TESLA policy as well as the initial key,
using the Multimedia Internet Keying (MIKEY) [RFC3830] protocol.
MIKEY defines an authentication and key management framework that can
be used for real-time applications (both for peer-to-peer
communication and group communication). In particular, [RFC3830] is
defined in a way that is intended to support SRTP in the first place
but is open to enhancements to be used for other purposes too.
Following the description in RFC 3830 [RFC3830] MIKEY is targeted for
point-to-point as well as for group communication. In the context of
group communication an administrator entity can distribute session
keys to the associated entities participating in the communication
session. This scenario is also applicable for TESLA where one entity
may provide information to many others in a way that the integrity of
the communicated information can be assured. The combination of
MIKEY and TESLA supports this group-based approach by utilizing the
MIKEY framework to distribute TESLA parameter information to all
involved entities. Note that this document only focuses on the
distribution of the parameters, not on the generation of those
parameters.
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MIKEY [RFC3830] itself describes three authentication and key
exchange protocols (symmetric key enryption, public key encryption,
and signed Diffie-Hellman) Extensions to the MIKEY key exchange
methods have been defined. A fourth key distribution method is
provided by [I-D.ietf-msec-mikey-dhhmac] and describes a symetrically
protected Diffie-Hellman key agreement. A further option has been
proposed in [I-D.ietf-msec-mikey-rsa-r] describing an enhanced
asymmetric exchange variant, supporting also inband certificate
exchange. All of the different key management schemes mentioned
above may be used to provide the TESLA parameters. The required
TESLA parameters to be exchanged are already described in [I-D.ietf-
msec-srtp-tesla], while this document describes their transport
within MIKEY.
The following security requirements have to be placed on the exchange
of TESLA parameters:
o Authentication and Integrity MUST be provided when sending the
TESLA parameters, especially for the initial key.
o Confidentiality MAY be provided for the TESLA parameters
These security requirements apply to the TESLA bootstrapping
procedure only. Security requirements for applications using TESLA
are beyond the scope of this document. Security aspects that relate
to TESLA itself are described in [RFC4082] and security issues for
TESLA usage for SRTP are covered in [I-D.ietf-msec-srtp-tesla].
It is important to note that this document is one piece of a complete
solution. Assuming that media traffic is to be secured using TESLA
as described in [I-D.ietf-msec-srtp-tesla] then (a) keying material
is required and (b) parameters for TESLA. This document contributes
the parameters and the authentication methods used in MIKEY to
provide the keying material. The parameter exchange for TESLA also
needs to be secured against tampering. This protection is provided
also by MIKEY.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
3. TESLA Parameter Overview
According to [I-D.ietf-msec-srtp-tesla] a number of transform
dependent parameters need to be provided for proper TESLA operation.
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The complete list of parameters can be found in Section 4.3 of
[I-D.ietf-msec-srtp-tesla]. Note, that the parameter 10 of
[I-D.ietf-msec-srtp-tesla], describing the lag of the receiver clock
relative to the sender clock, is omitted in this document since it
can be computed.
MIKEY already requires synchronized clocks, which also provides for
synchronization for TESLA. Moreover, Section 4.3, states an option
to use MIKEY for clock drift determination between sender and
receiver. Thus, this parameter does not need to be transmitted in
MIKEY directly.
The information in brackets provides the default values as specified
in Section 6.2 of [I-D.ietf-msec-srtp-tesla].
1. An identifier for the Pseudo Random Function (PRF), implementing
the one-way function F(x) in TESLA (F(x) is used to calculate
keys using a hash chain), e.g. to indicate a keyed hashing
function (default HMAC-SHA1).
2. A non-negative integer, determining the length of the F output,
i.e. the length of the keys in the chain (that is also the key
disclosed in an SRTP packet if TESLA is used in the SRTP
context) (default 160 bit).
3. An identifier for the PRF, implementing the one-way function
F'(x) in TESLA (to derive the keys for the TESLA MAC, from the
keys in the chain), e.g. to indicate a keyed hashing function
(default HMAC-SHA1).
4. A non-negative integer, determining the length of the output of
F', i.e. the length of the key for the TESLA MAC (default 160
bit).
5. An identifier for the TESLA MAC, that accepts the output of
F'(x) as its key, e.g. to indicate a keyed hashing function
(default HMAC-SHA1).
6. A non-negative integer, determining the length of the output of
the TESLA MAC (default 80 bit).
7. The beginning of the session for which a key will be applied.
8. The interval duration (in milliseconds), for which a dedicated
key will be used.
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9. The key disclosure delay (in number of intervals), characterizes
the period after which the key will be sent to the involved
entities (e.g., as part of SRTP packets).
10. Non-negative integer, determining the length of the key chain,
which is determined based up the expected duration of the
stream.
11. The initial key of the chain to which the sender has committed
himself.
4. Parameter encoding within MIKEY
As mentioned in Section 3, TESLA parameters need to be transported
before actually starting a session. MIKEY currently only defines a
payload for transporting the SRTP policy (see Section 6.10 of
[RFC3830]). This section describes the enhancement of MIKEY to allow
the transport of a TESLA policy and additionally the initial TESLA
key.
4.1. Security Policy payload (SP)
The Security Policy payload defines a set of policies that apply to a
specific security protocol. The definition here relies on the
security policy payload definition in [RFC3830].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next payload ! Policy no ! Prot type ! Policy param ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ length (cont) ! Policy param ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* Next payload (8 bits):
Identifies the payload that is added after
this payload. See Section 6.1 of [RFC3830] for
more details.
* Policy no (8 bits):
Each security policy payload must be given a
distinct number for the current MIKEY session by the
local peer. This number is used to map a cryptographic session
to a specific policy (see also Section 6.1.1 of [RFC3830]).
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* Prot type (8 bits):
This value defines the security protocol.
A second value needs to be defined as shown below:
(MIKEY already defines the value 0.)
Prot type | Value |
---------------------------
SRTP | 0 |
TESLA | 1 |
* Policy param length (16 bits):
This field defines the total length of the
policy parameters for the selected security protocol.
* Policy param (variable length):
This field defines the policy for the specific
security protocol.
The Policy param part is built up by a set of Type/Length/Value (TLV)
payloads. For each security protocol, a set of possible type/value
pairs can be negotiated as defined.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Type ! Length ! Value ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* Type (8 bits):
Specifies the type of the parameter.
* Length (8 bits):
Specifies the length of the Value field (in bytes).
* Value (variable length):
Specifies the value of the parameter.
4.2. TESLA policy
This policy specifies the parameters for TESLA. The types/values
that can be negotiated are defined by the following table. The
concrete default values are taken from [I-D.ietf-msec-srtp-tesla],
but other values may also be used:
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Type | Meaning | Possible values
---------------------------------------------------------------
1 | PRF identifier for f, realising F(x) | see below
2 | Length of PRF f output | 160
3 | PRF identifier for f', realising F'(x) | see below
4 | Length of PRF f' output | 160
5 | Identifier for the TESLA MAC | see below
6 | Length of TESLA MAC output | 80 (truncated)
7 | Start of session | in bytes
8 | Interval duration (in msec) | in bytes
9 | Key disclosure delay | in bytes
10| Key chain length (numer of intervals) | in bytes
11| local timestamp media receiver | see below
The time values stated in items 7 and 11 SHALL be transported in NTP-
UTC format, which is one of the three options described in Section
6.6 of [RFC3830]. For the policy item 8 a four-byte integer value
and for the policy item 9 a two-byte integer value is RECOMMENDED
carrying interval and key disclosure delay. Note that the policy
type 11 does NOT correspond to the TESLA parameter 11 stated in
Section 3, which is actually discussed in Section 4.4. Moreover, the
policy type 11 stated above is optional and SHOULD be used, if the
time synchronization described in Section 4.3 point two is used.
Otherwise it SHOULD be omitted.
For the PRF realising F(x), a one byte length is sufficient.
The currently defined possible values are:
TESLA PRF F(x) | Value
-----------------------
HMAC-SHA1 | 0
For the PRF realising F'(x), a one byte length is enough.
The currently defined possible values are:
TESLA PRF F'(x) | Value
-----------------------
HMAC-SHA1 | 0
For the TESLA MAC, a one byte length is enough.
The currently defined possible values are:
TESLA MAC | Value
-----------------------
HMAC-SHA1 | 0
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4.3. Time synchronization
MIKEY as well as TESLA require the time synchronization of the
communicating peers. MIKEY requires time sychronization to provide
timestamp-based replay protection for the one-roundtrip
authentication and key exchange protocols. TESLA, on the other hand,
needs this information to determine the clock drift between the
senders and the receivers in order to appropriately release the
disclosed key. Two alternatives are available for time
synchronization:
1. Usage of out-of-band synchronization using NTP [RFC1305]. This
approach is already recommended within [RFC3830]. The advantage
of this approach is the option to use the MIKEY key management
variants that perform within a half-roundtrip. The disadvantage
is the required time synchronization via an additional protocol.
2. [RFC4082] also sketches a possible inband synchronization in
Section 3.3.1. This approach is summarized here in the context
of MIKEY. Note, that here the actual TESLA policy payload is
transmitted as part of the MIKEY responder message.
* The data receiver, which would be the MIKEY initiator sets the
local time parameter t_r and sends it as part of the timestamp
payload as described in [RFC3830]. This value t_r needs to be
stored locally.
* Upon receipt of the MIKEY initiator message the data sender
replies with the MIKEY responder message, setting the local
time stamp at data receiver (parameter 11) to the value t_r
received in the MIKEY initiator message and sets his local
time as 64 bit UTC value t_s in the timestamp payload as
described in [RFC3830].
MIKEY initiator message
[MIKEY parameter incl. local timestamp (t_r)]
------------------>
MIKEY responder message
[MIKEY parameter incl. local timestamp (t_s), TESLA policy
payload, received local time stamp t_r]
<------------------
* Upon receiving the MIKEY responder message the data receiver
sets D_t = t_s - t_r + S, where S is an estimated bound on the
clock drift throughout the duration of the session.
This approach has the advantage that it does not require an
additional time synchronization protocol. The disadvantage is
the necessity to perform a full MIKEY handshake, to enable
correct parameter transport. Moreover this approach is direction
dependent, as it may only be applied if the media receiver is
also the MIKEY initiator.
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Out-of-band synchronization using NTP (i.e., alternative 1) is the
RECOMMENDED approach for clock synchronization. In scenarios where
the media receiver is also the MIKEY initiator piggybacking timestamp
information in MIKEY (i.e., alternative 2) MAY be used to allow for
inband determination of the clock drift between sender and receiver.
4.4. Key data transport within MIKEY's General Extension Payload
The General Extensions Payload was defined to allow possible
extensions to MIKEY without the need for defining a completely new
payload each time. This payload can be used in any MIKEY message and
is part of the authenticated/signed data part.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next payload ! Type ! Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* Next payload (8 bits):
Identifies the payload following this payload.
* Type (8 bits):
Identifies the type of general payload. MIKEY
already defines the Values 0 and 1.
This document introduces a new value (2).
Type | Value | Comments
----------------------------------------------------
Vendor ID | 0 | Vendor specific byte string
SDP IDs | 1 | List of SDP key mgmt IDs
TESLA I-Key | 2 | TESLA initial key
* Length (16 bits):
The length in bytes of the Data field.
* Data (variable length):
The general payload data.
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5. Security Considerations
The security properties of multi-media data in a multicast
environment depends on a number of building blocks.
SRTP-TESLA [I-D.ietf-msec-srtp-tesla] describes extensions for SRTP
[RFC3711] in order to support TESLA [RFC4082] for source
authentication in multicast scenarios. As such, security
considerations described with TESLA (see [PCST] and [RFC4082]), the
TESLA SRTP mapping [I-D.ietf-msec-srtp-tesla] and SRTP [RFC3711]
itself are relevant in this context.
Furthermore, since this document details bootstrapping of TESLA using
the Multimedia Internet Keying (MIKEY) [RFC3830] protocol the
security considerations of MIKEY are applicable to this document.
As a summary, in order for a multi-media application to support TESLA
the following protocol interactions (in relationship to this document
are necessary):
o MIKEY [RFC3830] is executed between the desired entities to
perform authentication and a secure distribution of keying
material. In order to subsequently use TESLA the parameters
described in this document are distributed using MIKEY. MIKEY
itself uses another protocol for parameter transport, namely the
Session Description Protocol (SDP, [RFC2327]), that might again be
used within Session Initiation Protocol (SIP, [RFC3261]) to setup
a session between the desired entities.
o After the algorithms, parameters and the session keys are
available at the respective communication entities data traffic
protection via SRTP-TESLA [I-D.ietf-msec-srtp-tesla] can be used.
SRTP-TESLA itself applies TESLA to the SRTP protocol and as such
the processing guidelines of TESLA need to be followed.
5.1. Man-in-the-Middle (MitM) Attack
Threat:
The exchange of security related parameters and algorithms without
mutual authentication of the two peers can allow an adversary to
perform a man-in-the-middle attack. The mechanisms described in
this document do not itself provide such an authentication and
integrity protection.
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Countermeasures:
Throughout the document it is assumed that the parameter exchange
is secured using another protocol, i.e., the exchange parameters
and algorithms are part of a authentication and key exchange
protocol, namely MIKEY. Source authentication of group and
multicast communication cannot be provided for the data traffic if
the prior signaling exchange did not provide facilities to
authenticate the source. Using an authentication protocol that
does not provide session keys as part of a successful protocol
exchange will make it impossible to derive the necessary
parameters required by TESLA. MIKEY provides session key
establishment. Additionally, the exchange of parameters and
algorithms MUST be authenticated and integrity protected. The
security protection of the parameter exchange needs to provide the
same level or a higher level of security.
5.2. Downgrading Attack
Threat:
The exchange of security-related parameters and algorithms is
always subject to downgrading whereby an adversary modifies some
(or all) of the provided parameters. For example, a few
parameters require that a supported hash algorithm is listed. To
mount an attack the adversary has to modify the list of provided
algorithms and to select the weakest one.
Countermeasures:
TESLA parameter bootstrapping MUST be integrity protected to
prevent modification of the parameters and their values.
Moreover, since unmodified parameters from an unknown source are
not useful, authentication MUST be provided. This functionality
is not provided by mechanisms described in this document. Instead
the capabilities of the underlying authentication and key exchange
protocol (MIKEY) are reused for this purpose.
5.3. Denial of Service Attack
Threat:
An adversary might want to modify parameters exchange between the
communicating entities in order to establish different state
information at the respective communication entities. For
example, an adversary might want to modify the key disclosure
delay or the interval duration in order to disrupt the
communication at a later state since the TESLA algorithm assumes
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that the participating communication entities know the same
parameter set.
Countermeasures:
The exchanged parameters and the parameters and algorithms MUST be
integrity protected to allow the recipient to detect whether an
adversary attempted to modify the exchanged information.
Authentication and key exchange algorithms provided by MIKEY offer
this protection.
5.4. Replay Attack
Threat:
An adversary who is able to eavesdrop one or multiple protocol
exchanges (MIKEY exchanges with the parameters described in this
document) might be able to replay the payloads in a later protocol
exchange. If the recipients accept the parameters and algorithms
(or even the messages that carry these payloads as well then a
Denial of Service, downgrading or a man-in-the-middle attack might
be the consequence (depending on the entire set of replayed
attributes and messages).
Countermeasures:
In order to prevent replay attacks a freshness guarantee MUST be
provided. As such, the TESLA bootstrapping message exchange MUST
be unique and fresh and the corresponding authentication and key
exchange protocol MUST provide the same properties. In fact, it
is essential to derive a unique and fresh session key as part of
the authentication and key exchange protocol run that MUST be
bound to the protocol session. This includes the exchanged
parameters.
5.5. Traffic Analysis
Threat:
An adversary might be able to learn parameters and algorithms, if
located along the signaling path. This information can then later
be used to mount attacks against the end-to-end multi-media
communication. In some high-security and military environments it
might even be desirable not to reveal information about the used
parameters to make it more difficult to launch an attack.
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Countermeasures:
Confidentity protection can be provided by a subset of the
available MIKEY authentication and key exchange protocols, namely
those providing public key encryption and symmetric key
encryption. The initial hash key, which is also one of the TESLA
bootstrapping parameters, does not require confidentiality
protection due to the properties of a hash chain.
6. IANA Considerations
This document requires an IANA registration for the following
attributes. The registries are provided by MIKEY [RFC3830].
Prot Type:
This attribute specifies the protocol type for the security
protocol as described in Section 4.1.
Type:
Identifies the type of the general payload. The General
Extensions Payload was defined to allow possible extensions to
MIKEY without the need for defining a completely new payload each
time. Section 4.4 describes this attribute in more detail.
Following the policies outlined in [RFC3830] the values in the range
up to 240 (including 240) for the above attributes are assigned after
Expert Review by the MSEC working group or its designated successor.
The values in the range from 241 to 255 are reserved for Private Use.
IANA needs to add the following attributes and their respective
values to an existing registry created in [RFC3830]:
Prot Type:
Prot Type | Value | Description
-----------------------------------------------------
TESLA | 1 | TESLA as a security protocol
The value of 1 for the 'Prot Type' must be added to the 'Prot
type' registry created by [RFC3830].
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Type:
Type | Value | Description
-------------------------------------------
TESLA I-Key | 2 | TESLA initial key
The value of 2 for the 'Type' must be added to the 'Type' registry
created by [RFC3830]. The values of 0 and 1 are already
registered in [RFC3830].
Furthermore, this document requires IANA to create two new
registries:
TESLA-PRF: Pseudo-random Function (PRF) used in the TESLA policy:
This attribute specifies values for pseudo-random functions used
in the the TESLA policy (see Section 4.2).
TESLA-MAC: MAC Function used in TESLA:
This attribute specifies values for pseudo-random functions used
in the the TESLA policy (see Section 4.2).
Following the policies outlined in [RFC2434] the values for the
TESLA-PRF and the TESLA-MAC registry in the range up to 240
(including 240) for the above attributes are assigned after Expert
Review by the MSEC working group or its designated successor. The
values in the range from 241 to 255 are reserved for Private Use.
IANA is requested to add the following values to the TESLA-PRF and
the TESLA-MAC registry:
TESLA-PRF:
PRF Function | Value
--------------------------
HMAC-SHA1 | 0
TESLA-MAC:
MAC Function | Value
--------------------------
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HMAC-SHA1 | 0
7. Acknowledgments
The authors would like to thank Mark Baugher and Ran Canetti for the
discussions in context of time synchronization. Additionally, we
would like to thank Lakshminath Dondeti, Russ Housley and Allison
Mankin for their document reviews and for their guidance.
8. References
8.1. Normative References
[I-D.ietf-msec-srtp-tesla]
Carrara, E. and M. Baugher, "The Use of TESLA in SRTP",
draft-ietf-msec-srtp-tesla-05 (work in progress),
October 2005.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[RFC3830] Arkko, J., Carrara, E., Lindholm, F., Naslund, M., and K.
Norrman, "MIKEY: Multimedia Internet KEYing", RFC 3830,
August 2004.
[RFC4082] Perrig, A., Song, D., Canetti, R., Tygar, J., and B.
Briscoe, "Timed Efficient Stream Loss-Tolerant
Authentication (TESLA): Multicast Source Authentication
Transform Introduction", RFC 4082, June 2005.
8.2. Informative References
[I-D.ietf-msec-mikey-dhhmac]
Euchner, M., "HMAC-authenticated Diffie-Hellman for
MIKEY", draft-ietf-msec-mikey-dhhmac-11 (work in
progress), April 2005.
[I-D.ietf-msec-mikey-rsa-r]
Ignjatic, D., "An additional mode of key distribution in
MIKEY: MIKEY-RSA-R", draft-ietf-msec-mikey-rsa-r-01 (work
in progress), October 2005.
Fries & Tschofenig Expires July 15, 2006 [Page 16]
Internet-Draft Bootstrapping TESLA January 2006
[PCST] Perrig, A., Canetti, R., Song, D., and D. Tygar,
""Efficient and Secure Source Authentication for
Multicast", in Proc. of Network and Distributed System
Security Symposium NDSS 2001, pp. 35-46", 2001.
[RFC1305] Mills, D., "Network Time Protocol (Version 3)
Specification, Implementation", RFC 1305, March 1992.
[RFC2327] Handley, M. and V. Jacobson, "SDP: Session Description
Protocol", RFC 2327, April 1998.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, March 2004.
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Authors' Addresses
Steffen Fries
Siemens
Otto-Hahn-Ring 6
Munich, Bavaria 81739
Germany
Email: steffen.fries@siemens.com
Hannes Tschofenig
Siemens
Otto-Hahn-Ring 6
Munich, Bavaria 81739
Germany
Email: Hannes.Tschofenig@siemens.com
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Internet-Draft Bootstrapping TESLA January 2006
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Fries & Tschofenig Expires July 15, 2006 [Page 19]
