Internet DRAFT - draft-herberg-manet-packetbb-sec
draft-herberg-manet-packetbb-sec
Mobile Ad hoc Networking (MANET) U. Herberg
Internet-Draft T. Clausen
Intended status: Standards Track LIX, Ecole Polytechnique
Expires: September 9, 2010 March 8, 2010
MANET Cryptographical Signature TLV Definition
draft-herberg-manet-packetbb-sec-03
Abstract
This document describes a general and flexible TLV (type-length-value
structure) for representing cryptographic signatures as well as
timestamps, using the generalized MANET packet/message format
[RFC5444]. It defines two Packet TLVs, two Message TLVs, and two
Address Block TLVs, for affixing cryptographic signatures and
timestamps to a packet, message and address, respectively.
Status of this Memo
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Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Applicability Statement . . . . . . . . . . . . . . . . . . . 4
4. Protocol Overview and Functioning . . . . . . . . . . . . . . 5
5. General Signature TLV Structure . . . . . . . . . . . . . . . 6
5.1. Rationale . . . . . . . . . . . . . . . . . . . . . . . . 6
6. General Timestamp TLV Structure . . . . . . . . . . . . . . . 7
7. Packet TLVs . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Packet SIGNATURE TLV . . . . . . . . . . . . . . . . . . . 7
7.2. Packet TIMESTAMP TLV . . . . . . . . . . . . . . . . . . . 8
8. Message TLVs . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Message SIGNATURE TLV . . . . . . . . . . . . . . . . . . 8
8.2. Message TIMESTAMP TLV . . . . . . . . . . . . . . . . . . 8
9. Address Block TLVs . . . . . . . . . . . . . . . . . . . . . . 8
9.1. Address Block SIGNATURE TLV . . . . . . . . . . . . . . . 9
9.2. Address Block TIMESTAMP TLV . . . . . . . . . . . . . . . 9
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
10.1. TLV Registrations . . . . . . . . . . . . . . . . . . . . 9
10.1.1. Expert Review: Evaluation Guidelines . . . . . . . . 9
10.1.2. Packet TLV Type Registrations . . . . . . . . . . . . 9
10.1.3. Message TLV Type Registrations . . . . . . . . . . . 10
10.1.4. Address Block TLV Type Registrations . . . . . . . . 11
10.2. New IANA Registries . . . . . . . . . . . . . . . . . . . 12
10.2.1. Expert Review: Evaluation Guidelines . . . . . . . . 12
10.2.2. Hash Function . . . . . . . . . . . . . . . . . . . . 12
10.2.3. Cryptographic Algorithm . . . . . . . . . . . . . . . 13
11. Security Considerations . . . . . . . . . . . . . . . . . . . 13
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
13.1. Normative References . . . . . . . . . . . . . . . . . . . 14
13.2. Informative References . . . . . . . . . . . . . . . . . . 14
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 15
A.1. Example of a Signed Message . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
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1. Introduction
This document:
o specifies two TLVs for carrying cryptographic signatures and
timestamps in packets, messages and address blocks as defined by
[RFC5444],
o requests IANA allocations for these Packet, Message, and Address
Block TLVs from the 0-223 Packet TLV range, the 0-127 Message TLV
range and the 0-127 Address Block TLV range from [RFC5444],
o describes how cryptographic signatures are calculated, taking (for
Message TLVs) into account the mutable message header fields
(<msg-hop-limit> and <msg-hop-count>) where these fields are
present in messages,
o requests creation of two IANA registries for recording code points
for hash function and signature calculation, respectively.
This document does not stipulate how to sign or validate messages. A
specification of a routing protocol or routing protocol extension,
using the security representation of this document, MUST specify
appropriate interpretation of the TLVs. This document does
specifically not suggest specific cryptographic algorithms or hash
functions, but rather establishes IANA registries for such.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119].
This document uses the terminology and notation defined in [RFC5444].
Additionally, it defines the following terminology:
o Hash-Function
A hash function is an algorithm that takes a message of any
length as input and produces a fixed-length string as output.
Hash functions are used in cryptography for authentication and
message integrity.
o Object
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An object, here, is any sequence of bytes that is used to
calculate the signature over (e.g. a packet, a message, an
address as defined in [RFC5444], a timestamp, or a combination
of these).
o Signature
A digital signature can be used to (i) authenticate the
originator and (ii) to assure that the object, which has been
signed, has not been altered in transit. In many cases, a
signature is calculated by encrypting a hash of the object,
which is the basic assumption of this specification.
o Timestamp
The timestamp indicates the time when the timestamp has been
created. If a timestamp is added to an object before signing
the object, this information can be useful to determine the
"freshness" of the signed object. "Old" objects can indicate
replayed objects. The minimal requirement for a timestamp is
to provide a logical representation of time (e.g. Lamport
time). Using timestamps may require - at least roughly -
synchronized clocks among the routers in the network.
3. Applicability Statement
The packet and message format defined in [RFC5444] accords MANET
routing protocols, using this format, the ability to carry additional
information in control messages, through inclusion of TLVs.
Information so included in a control message MAY be used by the
routing protocol, or by an extension of the routing protocol,
according to its specification.
This document specifies how to include a cryptographic signature for
a packet, message or address block by way of such TLVs. This
document also specifies how to treat "mutable" fields (<msg-hop-
count> and <msg-hop-limit>) in the message header when calculating
signatures, such that the resulting signature can be correctly
verified by any recipient, and how to include this signature. A
MANET routing protocol, or an extension of a MANET routing protocol,
MAY use such included cryptographic signatures for, for example,
rejecting messages where signature verification fails.
Basic MANET routing protocol specifications are often "oblivious to
security", however have a clause allowing a control message to be
rejected as "badly formed" prior to it being processed or forwarded.
Protocols such as [NHDP] and [OLSRv2] recognize external reasons
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(such as failure to verify a signature) as being reasons for
rejecting a message as "badly formed", and therefore "invalid for
processing". This architecture is a result of the observation that
with respect to security in MANETs, "one size rarely fits all" and
that MANET routing protocol deployment domains have varying security
requirements ranging from "unbreakable" to "virtually none". The
virtue of this approach is that MANET routing protocol specifications
(and implementations) can remain "generic", with extensions providing
proper deployment-domain specific security mechanisms.
The MANET routing protocol "security architecture", in which this
specification situates itself, can therefore be summarized as
follows:
o Security-oblivious MANET routing protocol specifications, with a
clause allowing an extension to reject a message (prior to
processing/forwarding) as "badly formed".
o MANET routing protocol security extensions, rejecting messages as
"badly formed", as appropriate for a given deployment-domain
specific security requirement.
o Code-points and an exchange format for information necessary for
specification of such security extensions.
This document addresses the last of these issues, by specifying a
common exchange format for cryptographic signatures. This document
also makes reservations from within the Packet TLV, Message TLV and
Address Block TLV registries of [RFC5444], to be used (and shared)
among MANET routing protocol security extensions. Finally, this
document establishes two IANA registries for code-points for hash
functions and cryptographic algorithms for use by protocols adhering
to [RFC5444].
With respect to [RFC5444], this document:
o is intended to be used in the non-normative, but intended, mode of
use of [RFC5444] as described in its Appendix B.
o is a specific example of the Security Considerations section of
[RFC5444] (the authentication part).
4. Protocol Overview and Functioning
This specification does not describe a protocol, nor does it mandate
specific router or protocol behavior. It represents a purely
syntactical representation of security related information for use
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with [RFC5444] messages and packets, as well as establishes IANA
registrations and registries.
5. General Signature TLV Structure
The following data structure allows representation of a cryptographic
signature, including specification of the appropriate hash function
and cryptographic algorithm used for calculating the signature. This
<signature> data structure is specified, using the regular expression
syntax of [RFC5444], as:
<signature> := <hash-function>
<cryptographic-algorithm>
<signature-value>
where:
<hash-function> is an 8-bit unsigned integer field specifying the
hash function.
<cryptographic-algorithm> is an 8-bit unsigned integer field
specifying the cryptographic algorithm.
<signature-value> is an unsigned integer field, whose length is
<tlv-length>-2, and which contains the cryptographic signature.
The basic version of this TLV assumes that calculating the signature
can be decomposed into:
signature-value = cryptographic-function(hash-function(message))
The hash function and the cryptographic algorithm correspond to the
IANA registry in the two registries set up by this specification, see
Section 10.
5.1. Rationale
The rationale for separating the hash function and the cryptographic
algorithm into two octets instead of having all combinations in a
single octet - possibly as TLV type extension - is twofold: First, if
further hash functions or cryptographic algorithms are added in the
future, the number space might not remain continuous. More
importantly, the number space of 256 possible combinations would be
rapidly exhausted: 16 different hash functions and 16 different
cryptographic algorithms would lead to exhaustion. As new or
improved cryptographic mechanism are continuously being developed and
introduced, this format should be able to accommodate such for the
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foreseeable future.
The rationale for not including a field that lists parameters of the
cryptographic signature in the TLV is the following: Before being
able to to validate a cryptographic signature, routers have to
exchange keys (e.g. public keys). Any additional parameters can be
exchanged together with the keys in this bootstrap process. It is
therefore not necessary, and would even entail an extra overhead, to
transmit the parameters within every message. One inherently
included parameter is the length of the signature, which is tlv-
length - 2 and which depends on the choice of the cryptographic
algorithm.
6. General Timestamp TLV Structure
The following data structure allows the representation of a
timestamp. This <timestamp> data structure is specified as:
<timestamp> := <time-value>
where:
<time-value> is an unsigned integer field, whose length is <tlv-
length>, and which contains the timestamp. The value of this
variable is to be interpreted by the routing protocol as specified
by the type extension of the Timestamp TLV (refer to Table 1).
A timestamp is essentially "freshness information". As such, its
setting and interpretation is to be determined by the routing
protocol (or the extension to a routing protocol) that uses it, and
may e.g. correspond to a UNIX-timestamp, GPS timestamp or a simple
sequence number. This is out of the scope of this specification.
7. Packet TLVs
Two Packet TLVs are defined, for including the cryptographic
signature of a packet, and for including the timestamp indicating the
time at which the cryptographic signature was calculated.
7.1. Packet SIGNATURE TLV
A Packet SIGNATURE TLV is an example of a Signature TLV as described
in Section 5. When calculating the <signature-value> for a Packet,
the signature is calculated over the entire Packet, including the
packet header, all Packet TLVs (other than Packet SIGNATURE TLVs) and
all included Messages and their message headers.
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7.2. Packet TIMESTAMP TLV
A Packet TIMESTAMP TLV is an example of a Timestamp TLV as described
in Section 6. If a packet contains a TIMESTAMP TLV and a SIGNATURE
TLV, the TIMESTAMP TLV SHOULD be added to the packet before the
SIGNATURE TLV, in order that it be included in the calculation of the
signature.
8. Message TLVs
Two Message TLVs are defined, for including the cryptographic
signature of a message, and for including the timestamp indicating
the time at which the cryptographic signature was calculated.
8.1. Message SIGNATURE TLV
A Message SIGNATURE TLV is an example of a Signature TLV as described
in Section 5. When determining the <signature-value> for a message,
the signature is calculated over the entire message with the
following considerations:
o the fields <msg-hop-limit> and <msg-hop-count> MUST be both
assumed to have the value 0 (zero).
o all Message SIGNATURE TLVs MUST be removed before calculating the
signature, and the message size as well as the Message TLV block
size MUST be recalculated accordingly. The TLVs can be restored
after having calculated the signature value.
8.2. Message TIMESTAMP TLV
A Message TIMESTAMP TLV is an example of a Timestamp TLV as described
in Section 6. If a message contains a TIMESTAMP TLV and a SIGNATURE
TLV, the TIMESTAMP TLV SHOULD be added to the message before the
SIGNATURE TLV, in order that it be included in the calculation of the
signature.
9. Address Block TLVs
Two Address Block TLVs are defined, for associating a cryptographic
signature to an address, and for including the timestamp indicating
the time at which the cryptographic signature was calculated.
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9.1. Address Block SIGNATURE TLV
An Address Block SIGNATURE TLV is an example of a Signature TLV as
described in Section 5. The signature can be calculated over any
object, including, for example, the address to which this TLV is
associated to.
9.2. Address Block TIMESTAMP TLV
An Address Block TIMESTAMP TLV is an example of a Timestamp TLV as
described in Section 6. If both a TIMESTAMP TLV and a SIGNATURE TLV
are associated with an address, the timestamp value should be
considered when calculating the value of the signature.
10. IANA Considerations
10.1. TLV Registrations
This specification defines:
o two Packet TLV types which must be allocated from the 0-223 range
of the "Assigned Packet TLV Types" repository of [RFC5444] as
specified in Table 1,
o two Message TLV types which must be allocated from the 0-127 range
of the "Assigned Message TLV Types" repository of [RFC5444] as
specified in Table 2,
o and two Address Block TLV types which must be allocated from the
0-127 range of the "Assigned Address Block TLV Types" repository
of [RFC5444] as specified in Table 3.
IANA is requested to assign the same numerical value to the Packet
TLV, Message TLV and Address Block TLV types with the same name.
10.1.1. Expert Review: Evaluation Guidelines
For the registries for TLV type extensions where an Expert Review is
required, the designated expert SHOULD take the same general
recommendations into consideration as are specified by [RFC5444].
10.1.2. Packet TLV Type Registrations
The Packet TLVs as specified in Table 1 must be allocated from the
"Packet TLV Types" namespace of [RFC5444].
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+-----------+------+-----------+------------------------------------+
| Name | Type | Type | Description |
| | | Extension | |
+-----------+------+-----------+------------------------------------+
| SIGNATURE | TBD3 | 0 | Signature of a packet |
| | | 1-223 | Expert Review |
| | | 224-255 | Experimental Use |
| TIMESTAMP | TBD4 | 0 | Unsigned timestamp of arbitrary |
| | | | length, given by the tlv-length |
| | | | field. The timestamp is assumed to |
| | | | increase strictly monotonously by |
| | | | steps of 1. The MANET routing |
| | | | protocol has to define how to |
| | | | interpret this timestamp |
| | | 1 | Unsigned 32-bit timestamp as |
| | | | specified in [POSIX] |
| | | 2 | NTP timestamp format as defined in |
| | | | [RFC4330] |
| | | 3 | Signed timestamp of arbitrary |
| | | | length with no constraints such as |
| | | | monotonicity. In particular, it |
| | | | may represent any random value |
| | | 4-223 | Expert Review |
| | | 224-255 | Experimental Use |
+-----------+------+-----------+------------------------------------+
Table 1: Packet TLV types
10.1.3. Message TLV Type Registrations
The Message TLVs as specified in Table 2 must be allocated from the
"Message TLV Types" namespace of [RFC5444].
+-----------+------+-----------+------------------------------------+
| Name | Type | Type | Description |
| | | Extension | |
+-----------+------+-----------+------------------------------------+
| SIGNATURE | TBD1 | 0 | Signature of a message |
| | | 1-223 | Expert Review |
| | | 224-255 | Experimental Use |
| TIMESTAMP | TBD2 | 0 | Unsigned timestamp of arbitrary |
| | | | length, given by the tlv-length |
| | | | field. The timestamp is assumed to |
| | | | increase strictly monotonously by |
| | | | steps of 1. The MANET routing |
| | | | protocol has to define how to |
| | | | interpret this timestamp |
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| | | 1 | Unsigned 32-bit timestamp as |
| | | | specified in [POSIX] |
| | | 2 | NTP timestamp format as defined in |
| | | | [RFC4330] |
| | | 3 | Signed timestamp of arbitrary |
| | | | length with no constraints such as |
| | | | monotonicity. In particular, it |
| | | | may represent any random value |
| | | 4-223 | Expert Review |
| | | 224-255 | Experimental Use |
+-----------+------+-----------+------------------------------------+
Table 2: Message TLV types
10.1.4. Address Block TLV Type Registrations
The Address Block TLVs as specified in Table 3 must be allocated from
the "Address Block TLV Types" namespace of [RFC5444].
+-----------+------+-----------+------------------------------------+
| Name | Type | Type | Description |
| | | Extension | |
+-----------+------+-----------+------------------------------------+
| SIGNATURE | TBD1 | 0 | Signature of an object (e.g. an |
| | | | address) |
| | | 1-223 | Expert Review |
| | | 224-255 | Experimental Use |
| TIMESTAMP | TBD2 | 0 | Unsigned timestamp of arbitrary |
| | | | length, given by the tlv-length |
| | | | field. The timestamp is assumed to |
| | | | increase strictly monotonously by |
| | | | steps of 1. The MANET routing |
| | | | protocol has to define how to |
| | | | interpret this timestamp |
| | | 1 | Unsigned 32-bit timestamp as |
| | | | specified in [POSIX] |
| | | 2 | NTP timestamp format as defined in |
| | | | [RFC4330] |
| | | 3 | Signed timestamp of arbitrary |
| | | | length with no constraints such as |
| | | | monotonicity. In particular, it |
| | | | may represent any random value |
| | | 4-223 | Expert Review |
| | | 224-255 | Experimental Use |
+-----------+------+-----------+------------------------------------+
Table 3: Address Block TLV types
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10.2. New IANA Registries
This document introduces three namespaces that have been registered:
Packet TLV Types, Message TLV Types, and Address Block TLV Types.
This section specifies IANA registries for these namespaces and
provides guidance to the Internet Assigned Numbers Authority
regarding registrations in these namespaces.
The following terms are used with the meanings defined in [BCP26]:
"Namespace", "Assigned Value", "Registration", "Unassigned",
"Reserved", "Hierarchical Allocation", and "Designated Expert".
The following policies are used with the meanings defined in [BCP26]:
"Private Use", "Expert Review", and "Standards Action".
10.2.1. Expert Review: Evaluation Guidelines
For the registries for the following tables where an Expert Review is
required, the designated expert SHOULD take the same general
recommendations into consideration as are specified by [RFC5444].
10.2.2. Hash Function
IANA is requested to create a new registry for the hash functions
that can be used when creating a signature. The initial assignments
and allocation policies are specified in Table 4.
+-------------+-----------+-----------------------------------------+
| Hash | Algorithm | Description |
| function | | |
| value | | |
+-------------+-----------+-----------------------------------------+
| 0 | none | The "identity function": the hash value |
| | | of an object is the object itself |
| 1 | MD5 | The hash function as specified in |
| | | [RFC1321] |
| 2 | SHA1 | The hash function as specified in |
| | | [RFC3174] |
| 3 | SHA256 | The hash function as specified in |
| | | [SHA256] |
| 4-223 | | Expert Review |
| 224-255 | | Experimental Use |
+-------------+-----------+-----------------------------------------+
Table 4: Hash-Function registry
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10.2.3. Cryptographic Algorithm
IANA is requested to create a new registry for the cryptographic
algorithm. Initial assignments and allocation policies are specified
in Table 5.
+-----------------+-----------+-------------------------------------+
| Cryptographic | Algorithm | Description |
| algorithm value | | |
+-----------------+-----------+-------------------------------------+
| 0 | none | The "identity function": the value |
| | | of an encrypted hash is the hash |
| | | itself |
| 1 | RSA | RSA as specified in [RFC2437] |
| 2 | DSA | DSA as specified in [DSA] |
| 3 | HMAC | HMAC as specified in [RFC2104] |
| 4 | 3DES | 3DES as specified in [3DES] |
| 5 | AES | AES as specified in [AES] |
| 6-223 | | Expert Review |
| 224-255 | | Experimental Use |
+-----------------+-----------+-------------------------------------+
Table 5: Cryptographic algorithm registry
11. Security Considerations
This document does not specify a protocol itself. However, it
provides a syntactical component for cryptographic signatures of
messages and packets as defined in [RFC5444]. It can be used to
address security issues of a protocol or extension that uses the
component specified in this document. As such, it has the same
security considerations as [RFC5444].
In addition, a protocol that includes this component MUST specify the
usage as well as the security that is attained by the cryptographic
signatures of a message or a packet.
As an example, a routing protocol that uses this component to reject
"badly formed" messages if a control message does not contain a valid
signature, should indicate the security assumption that if the
signature is valid, the message is considered valid. It also should
indicate the security issues that are counteracted by this measure
(e.g. link or identity spoofing) as well as the issues that are not
counteracted (e.g. compromised keys).
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12. Acknowledgements
The authors would like to thank Jerome Milan (Ecole Polytechnique)
for his advice as cryptographer. In addition, many thanks to Alan
Cullen (BAE), Justin Dean (NRL), Christopher Dearlove (BAE), and
Henning Rogge (FGAN) for their constructive comments on the document.
13. References
13.1. Normative References
[BCP26] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226, BCP 26,
May 2008.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, BCP 14, March 1997.
[RFC5444] Clausen, T., Dearlove, C., Dean, J., and C. Adjih,
"Generalized MANET Packet/Message Format", RFC 5444,
February 2009.
13.2. Informative References
[3DES] American National Standards Institute, "Triple Data
Encryption Algorithm Modes of Operation", ANSI X9.52-1998,
1998.
[AES] National Institute of Standards & Technology, "Advanced
Encryption Standard (AES)", FIPS 197, November 2001.
[DSA] National Institute of Standards & Technology, "Digital
Signature Standard", NIST, FIPS PUB 186, May 1994.
[NHDP] Clausen, T., Dean, J., and C. Dearlove, "MANET
Neighborhood Discovery Protocol (NHDP)", work in
progress draft-ietf-manet-nhdp-11.txt, October 2009.
[OLSRv2] Clausen, T., Dearlove, C., and P. Jacquet, "The Optimized
Link State Routing Protocol version 2", work in
progress draft-ietf-manet-olsrv2-10.txt, September 2009.
[POSIX] IEEE Computer Society, "1003.1-2008 Standard for
Information Technology - Portable Operating System
Interface (POSIX)", Base Specifications Issue 7,
December 2008.
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[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
April 1992.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104,
February 1997.
[RFC2437] Kaliski, B. and J. Staddon, "PKCS #1: RSA Cryptography
Specifications Version 2.0", RFC 2437, October 1998.
[RFC3174] Eastlake, D. and P. Jones, "US Secure Hash Algorithm 1
(SHA1)", RFC 3174, September 2001.
[RFC4330] Mills, D., "Simple Network Time Protocol (SNTP) Version 4
for IPv4, IPv6 and OSI", RFC 4330, January 2006.
[SHA256] National Institute of Standards and Technology, "Secure
Hash Algorithm", NIST FIPS 180-2, August 2002.
Appendix A. Examples
A.1. Example of a Signed Message
The sample message depicted in Figure 1 is taken from the appendix of
[RFC5444]. However, a SIGNATURE Message TLV has been added. It is
assumed that the SIGNATURE TLV type is lesser than the TLV type of
the second message TLV (i.e. it comes first in the order of Message
TLVs). The TLV value represents a 16 octet long signature of the
whole message.
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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 0 0 0 1 0 0 0| Packet Sequence Number | Message Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 1 1 1 0 0 1 1|0 0 0 0 0 0 0 0 0 1 0 0 1 1 0 0| Orig Addr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Originator Address (cont) | Hop Limit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hop Count | Message Sequence Number |0 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1 1 1 1 0| SIGNATURE |0 0 0 1 0 0 0 0|0 0 0 1 0 0 1 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hash Func | Crypto Func | Signature Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Signature Value (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Signature Value (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Signature Value (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Signature Value (cont) | TLV Type |0 0 0 1 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 1 1 0| Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value (cont) |0 0 0 0 0 0 1 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 1 1 0 0 0 0|0 0 0 0 0 0 1 0| Mid |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mid | Prefix Length |0 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 0|0 0 0 0 0 0 1 1|1 0 0 0 0 0 0 0|0 0 0 0 0 0 1 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Head | Mid |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Mid | Mid |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 1| TLV Type |0 0 0 1 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 1 0| Value | TLV Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 1 0 0 0 0 0| Index Start | Index Stop |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Example message with signature
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Authors' Addresses
Ulrich Herberg
LIX, Ecole Polytechnique
91128 Palaiseau Cedex,
France
Phone: +33-1-6933-4126
Email: ulrich@herberg.name
URI: http://www.herberg.name/
Thomas Heide Clausen
LIX, Ecole Polytechnique
91128 Palaiseau Cedex,
France
Phone: +33 6 6058 9349
Email: T.Clausen@computer.org
URI: http://www.thomasclausen.org/
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