draft-ietf-tls-oob-pubkey-10.txt   draft-ietf-tls-oob-pubkey-11.txt 
TLS P. Wouters, Ed. TLS P. Wouters, Ed.
Internet-Draft Red Hat Internet-Draft Red Hat
Intended status: Standards Track H. Tschofenig, Ed. Intended status: Standards Track H. Tschofenig, Ed.
Expires: April 22, 2014 Nokia Solutions and Networks Expires: July 22, 2014
J. Gilmore J. Gilmore
S. Weiler S. Weiler
SPARTA, Inc. SPARTA, Inc.
T. Kivinen T. Kivinen
AuthenTec AuthenTec
October 19, 2013 January 18, 2014
Using Raw Public Keys in Transport Layer Security (TLS) and Datagram Using Raw Public Keys in Transport Layer Security (TLS) and Datagram
Transport Layer Security (DTLS) Transport Layer Security (DTLS)
draft-ietf-tls-oob-pubkey-10.txt draft-ietf-tls-oob-pubkey-11.txt
Abstract Abstract
This document specifies a new certificate type and two TLS extensions This document specifies a new certificate type and two TLS extensions
for exchanging raw public keys in Transport Layer Security (TLS) and for exchanging raw public keys in Transport Layer Security (TLS) and
Datagram Transport Layer Security (DTLS) for use with out-of-band Datagram Transport Layer Security (DTLS). The new certificate type
public key validation. allows raw public keys to be used for authentication.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 22, 2014. This Internet-Draft will expire on July 22, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Structure of the Raw Public Key Extension . . . . . . . . . . 4 3. Structure of the Raw Public Key Extension . . . . . . . . . . 4
4. TLS Client and Server Handshake Behavior . . . . . . . . . . 6 4. TLS Client and Server Handshake Behavior . . . . . . . . . . 6
4.1. Client Hello . . . . . . . . . . . . . . . . . . . . . . 7 4.1. Client Hello . . . . . . . . . . . . . . . . . . . . . . 7
4.2. Server Hello . . . . . . . . . . . . . . . . . . . . . . 7 4.2. Server Hello . . . . . . . . . . . . . . . . . . . . . . 8
4.3. Client Authentication . . . . . . . . . . . . . . . . . . 8 4.3. Client Authentication . . . . . . . . . . . . . . . . . . 9
5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1. TLS Server uses Raw Public Key . . . . . . . . . . . . . 8 5.1. TLS Server uses Raw Public Key . . . . . . . . . . . . . 9
5.2. TLS Client and Server use Raw Public Keys . . . . . . . . 9 5.2. TLS Client and Server use Raw Public Keys . . . . . . . . 10
5.3. Combined Usage of Raw Public Keys and X.509 Certificate . 10 5.3. Combined Usage of Raw Public Keys and X.509 Certificate . 11
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
9.1. Normative References . . . . . . . . . . . . . . . . . . 13 9.1. Normative References . . . . . . . . . . . . . . . . . . 14
9.2. Informative References . . . . . . . . . . . . . . . . . 14 9.2. Informative References . . . . . . . . . . . . . . . . . 15
Appendix A. Example Encoding . . . . . . . . . . . . . . . . . . 14 Appendix A. Example Encoding . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction 1. Introduction
Traditionally, TLS client and server public keys are obtained in PKIX Traditionally, TLS client and server public keys are obtained in PKIX
containers in-band as part of the TLS handshake procedure and are containers in-band as part of the TLS handshake procedure and are
validated using trust anchors based on a PKIX certification authority validated using trust anchors based on a [PKIX] certification
(CA) [RFC5280]. This method can add a complicated trust relationship authority (CA). This method can add a complicated trust relationship
that is difficult to validate. Examples of such complexity can be that is difficult to validate. Examples of such complexity can be
seen in [Defeating-SSL]. seen in [Defeating-SSL]. TLS is, however, also commonly used with
self-signed certificates in smaller deployments where the self-signed
certificates are distributed to all involved protocol end points out-
of-band. This practice does, however, still requires the overhead of
the certificate generation even though none of the information found
in the certificate is actually used.
Alternative methods are available that allow a TLS clients/servers to Alternative methods are available that allow a TLS client/server to
obtain the TLS servers/client public key: obtain the TLS server/client public key:
o TLS clients can obtain the TLS server public key from a DNSSEC o The TLS client can obtain the TLS server public key from a DNSSEC
secured resource records using DANE [RFC6698]. secured resource records using DANE [RFC6698].
o The TLS client or server public key is obtained from a certificate o The TLS client or server public key is obtained from a [PKIX]
chain via a Lightweight Directory Access Protocol (LDAP) [RFC4511] certificate chain from an Lightweight Directory Access Protocol
server or web page. (LDAP) [LDAP] server or web page.
o The TLS client and server public key is provisioned into the o The TLS client and server public key is provisioned into the
operating system firmware image, and updated via software updates. operating system firmware image, and updated via software updates.
For example: For example:
Some smart objects use the UDP-based Constrained Application Some smart objects use the UDP-based Constrained Application
Protocol (CoAP) [I-D.ietf-core-coap] to interact with a Web server Protocol (CoAP) [I-D.ietf-core-coap] to interact with a Web server
to upload sensor data at a regular intervals, such as temperature to upload sensor data at a regular intervals, such as temperature
readings. CoAP [I-D.ietf-core-coap] can utilize DTLS for securing readings. CoAP can utilize DTLS for securing the client-to-server
the client-to-server communication. As part of the manufacturing communication. As part of the manufacturing process, the embedded
process, the embedded device may be configured with the address device may be configured with the address and the public key of a
and the public key of a dedicated CoAP server, as well as a public dedicated CoAP server, as well as a public/private key pair for
/private key pair for the client itself. the client itself.
This document introduces the use of raw public keys in TLS/DTLS. Raw This document introduces the use of raw public keys in TLS/DTLS.
public key thereby means that only a sub-set of the information found With raw public keys, only a subset of the information found in
in typical certificates is utilized, namely the SubjectPublicKeyInfo typical certificates is utilized: namely, the SubjectPublicKeyInfo
structure of a PKIX certificates that carries the parameters structure of a PKIX certificates that carries the parameters
necessary to describe the public key. Other parameters also found in necessary to describe the public key. Other parameters found in PKIX
a PKIX certificate are omitted. A consequence of omitting various certificates are omitted. By omitting various certificate-related
certificate related structures is that the resulting raw public key structures, the resulting raw public key is kept fairly small in
is fairly small (compared to the original certificate) and does not comparison to the original certificate, and the code to process the
require codepaths for the ASN.1 parser, for certificate path keys requires only a minimalistic ASN.1 parser, no code for
validation and other PKIX related processing tasks. To further certificate path validation, and other PKIX related processing tasks
reduce the size of the exchanged information this specification can are also omitted. Note, however, the SubjectPublicKeyInfo structure
be combined with the TLS Cached Info extension is still in an ASN.1 format. To further reduce the size of the
[I-D.ietf-tls-cached-info], which enables TLS endpoints to just exchanged information this specification can be combined with the TLS
exchange fingerprints of their public keys (rather than the full Cached Info extension [I-D.ietf-tls-cached-info], which enables TLS
public keys). peers to just exchange fingerprints of their public keys.
The mechanism defined herein only provides authentication when an The mechanism defined herein only provides authentication when an
out-of-band mechanism is also used to bind the public key to the out-of-band mechanism is also used to bind the public key to the
entity presenting the key. entity presenting the key.
This document is structured as follows: Section 3 defines the Section 3 defines the structure of the two new TLS extensions
structure of the two new TLS extensions "client_certificate_type" and "client_certificate_type" and "server_certificate_type", which can be
"server_certificate_type", which can be used as part of an extended used as part of an extended TLS handshake when raw public keys are to
TLS handshake when raw public keys are to be used. Section 4 defines be used. Section 4 defines the behavior of the TLS client and the
the behavior of the TLS client and the TLS server. Example exchanges TLS server. Example exchanges are described in Section 5. Section 6
are described in Section 5. Finally, in Section 7 this document also describes security considerations with this approach. Finally, in
registers a new value to the IANA certificate types registry for the Section 7 this document also registers a new value to the IANA
support of raw public keys. certificate types registry for the support of raw public keys.
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 RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
We use the terms 'TLS server' and 'server' as well as 'TLS client' We use the terms 'TLS server' and 'server' as well as 'TLS client'
and 'client' interchangable. and 'client' interchangable.
3. Structure of the Raw Public Key Extension 3. Structure of the Raw Public Key Extension
This section defines the two TLS extensions 'client_certificate_type' This section defines the two TLS extensions 'client_certificate_type'
and 'server_certificate_type', which can be used as part of an and 'server_certificate_type', which can be used as part of an
extended TLS handshake when raw public keys are used. Section 4 extended TLS handshake when raw public keys are used. Section 4
defines the behavior of the TLS client and the TLS server using this defines the behavior of the TLS client and the TLS server using this
extension. extension.
This specification reuses the SubjectPublicKeyInfo structure to This specification uses raw public keys whereby the already available
encode the raw public key and to convey that information within the encoding used in a PKIX certificate in the form of a
TLS handshake the Certificate payload is utilized as a container, as SubjectPublicKeyInfo structure is reused. To carry the raw public
shown in Figure 1. The shown Certificate structure is an adaptation key within the TLS handshake the Certificate payload is used as a
of its original form [RFC5246]. container, as shown in Figure 1. The shown Certificate structure is
an adaptation of its original form [RFC5246].
opaque ASN.1Cert<1..2^24-1>; opaque ASN.1Cert<1..2^24-1>;
struct { struct {
select(certificate_type){ select(certificate_type){
// certificate type defined in this document. // certificate type defined in this document.
case RawPublicKey: case RawPublicKey:
opaque ASN.1_subjectPublicKeyInfo<1..2^24-1>; opaque ASN.1_subjectPublicKeyInfo<1..2^24-1>;
skipping to change at page 4, line 43 skipping to change at page 4, line 50
ASN.1Cert certificate_list<0..2^24-1>; ASN.1Cert certificate_list<0..2^24-1>;
// Additional certificate type based on TLS // Additional certificate type based on TLS
// Certificate Type Registry // Certificate Type Registry
}; };
} Certificate; } Certificate;
Figure 1: Certificate Payload as a Container for the Raw Public Key. Figure 1: Certificate Payload as a Container for the Raw Public Key.
The SubjectPublicKeyInfo structure is defined in Section 4.1 of RFC The SubjectPublicKeyInfo structure is defined in Section 4.1 of RFC
5280 [RFC5280] and does not only contain the raw keys, such as the 5280 [PKIX] and does not only contain the raw keys, such as the
public exponent and the modulus of an RSA public key, but also an public exponent and the modulus of an RSA public key, but also an
algorithm identifier. The algorithm identifier can also include algorithm identifier. The algorithm identifier can also include
parameters. The structure, as shown in Figure 2, is represented in a parameters. The SubjectPublicKeyInfo value in the Certificate
DER encoded ASN.1 format [X.690] and therefore contains length payload MUST contain the DER encoding [X.690] of the
information as well. An example is provided in Appendix A. SubjectPublicKeyInfo. The structure, as shown in Figure 2, therefore
also contains length information as well. An example is provided in
Appendix A.
SubjectPublicKeyInfo ::= SEQUENCE { SubjectPublicKeyInfo ::= SEQUENCE {
algorithm AlgorithmIdentifier, algorithm AlgorithmIdentifier,
subjectPublicKey BIT STRING } subjectPublicKey BIT STRING }
AlgorithmIdentifier ::= SEQUENCE { AlgorithmIdentifier ::= SEQUENCE {
algorithm OBJECT IDENTIFIER, algorithm OBJECT IDENTIFIER,
parameters ANY DEFINED BY algorithm OPTIONAL } parameters ANY DEFINED BY algorithm OPTIONAL }
Figure 2: SubjectPublicKeyInfo ASN.1 Structure. Figure 2: SubjectPublicKeyInfo ASN.1 Structure.
The algorithm identifiers are Object Identifiers (OIDs). RFC 3279 The algorithm identifiers are Object Identifiers (OIDs). RFC 3279
[RFC3279] and [RFC5480], for example, define the following OIDs shown [RFC3279] and [RFC5480], for example, define the following OIDs shown
in Figure 3. Note that this list is not exhaustive and more OIDs may in Figure 3. Note that this list is not exhaustive and more OIDs may
be defined in future RFCs. RFC 5480 also defines a number of OIDs. be defined in future RFCs. RFC 5480 also defines a number of OIDs.
Key Type | Document | OID Key Type | Document | OID
-----------------------+----------------------------+------------------- -----------------------+----------------------------+-------------------
RSA | Section 2.3.1 of RFC 3279 | 1.2.840.113549.1.1 RSA | Section 2.3.1 of RFC 3279 | 1.2.840.113549.1.1
.......................|............................|................... .......................|............................|...................
Digital Signature | | Digital Signature | |
Algorithm (DSA) | Section 2.3.2 of RFC 3279 | 1.2.840.10040.4.1 Algorithm (DSA) | Section 2.3.2 of RFC 3279 | 1.2.840.10040.4.1
.......................|............................|................... .......................|............................|...................
Elliptic Curve | | Elliptic Curve | |
Digital Signature | | Digital Signature | |
Algorithm (ECDSA) | Section 2 of RFC 5480 | 1.2.840.10045.2.1 Algorithm (ECDSA) | Section 2 of RFC 5480 | 1.2.840.10045.2.1
-----------------------+----------------------------+------------------- -----------------------+----------------------------+-------------------
----------------------+----------------------------+-------------------
Figure 3: Example Algorithm Object Identifiers. Figure 3: Example Algorithm Object Identifiers.
The extension format for extended client hellos and extended server, The extension format for extended client and server hellos, which
via the "extension_data" field, is used to carry the uses the "extension_data" field, is used to carry the
ClientCertTypeExtension and the ServerCertTypeExtension structures. ClientCertTypeExtension and the ServerCertTypeExtension structures.
These two structures are shown in Figure 4. The CertificateType These two structures are shown in Figure 4. The CertificateType
structure is an enum with values taken from the 'TLS Certificate structure is an enum with values taken from the 'TLS Certificate
Type' registry [TLS-Certificate-Types-Registry]. Type' registry [TLS-Certificate-Types-Registry].
struct { struct {
select(ClientOrServerExtension) select(ClientOrServerExtension) {
case client: case client:
CertificateType client_certificate_types<1..2^8-1>; CertificateType client_certificate_types<1..2^8-1>;
case server: case server:
CertificateType client_certificate_type; CertificateType client_certificate_type;
} }
} ClientCertTypeExtension; } ClientCertTypeExtension;
struct { struct {
select(ClientOrServerExtension) select(ClientOrServerExtension) {
case client: case client:
CertificateType server_certificate_types<1..2^8-1>; CertificateType server_certificate_types<1..2^8-1>;
case server: case server:
CertificateType server_certificate_type; CertificateType server_certificate_type;
} }
} ServerCertTypeExtension; } ServerCertTypeExtension;
Figure 4: CertTypeExtension Structure. Figure 4: CertTypeExtension Structure.
4. TLS Client and Server Handshake Behavior 4. TLS Client and Server Handshake Behavior
skipping to change at page 7, line 4 skipping to change at page 7, line 26
certificate, certificate,
client_key_exchange, client_key_exchange,
certificate_verify, certificate_verify,
change_cipher_spec, change_cipher_spec,
finished -> finished ->
<- change_cipher_spec, <- change_cipher_spec,
finished finished
Application Data <-------> Application Data Application Data <-------> Application Data
Figure 5: Basic Raw Public Key TLS Exchange. Figure 5: Basic Raw Public Key TLS Exchange.
4.1. Client Hello 4.1. Client Hello
In order to indicate the support of raw public keys, clients include In order to indicate the support of raw public keys, clients include
the 'client_certificate_type' and/or the 'server_certificate_type' the 'client_certificate_type' and/or the 'server_certificate_type'
extensions in an extended client hello message. The hello extension extensions in an extended client hello message. The hello extension
mechanism is described in Section 7.4.1.4 of TLS 1.2 [RFC5246]. mechanism is described in Section 7.4.1.4 of TLS 1.2 [RFC5246].
The 'client_certificate_type' sent in the client hello indicates the The 'client_certificate_type' in the client hello indicates the
certificate types the client is able to provide to the server, when certificate types the client is able to provide to the server, when
requested using a certificate_request message. requested using a certificate_request message.
The 'server_certificate_type' in the client hello indicates the types The 'server_certificate_type' in the client hello indicates the types
of certificates the client is able to process when provided by the of certificates the client is able to process when provided by the
server in a subsequent certificate payload. server in a subsequent certificate payload.
The 'client_certificate_type' and 'server_certificate_type' sent in The 'client_certificate_type' and 'server_certificate_type' sent in
the client hello may carry a list of supported certificate types, the client hello may carry a list of supported certificate types,
sorted by client preference. It is a list in the case where the sorted by client preference. It is a list in the case where the
client supports multiple certificate types. client supports multiple certificate types.
The TLS client MUST omit the 'client_certificate_type' extension in The TLS client MUST omit the 'client_certificate_type' extension in
the client hello if it does not possess a client certificate or is the client hello if it does not possess a raw public key/certificate
not configured to use one with the given TLS server. The TLS client that it can provide to the server when requested using a
MUST omit the 'server_certificate_type' extension in the client hello certificate_request message or is not configured to use one with the
if it is unable to process any certificate types from the server given TLS server. The TLS client MUST omit the
(which is a situation that should not occur in normal circumstances). 'server_certificate_type' extension in the client hello if it is
unable to process raw public keys or other certificate types
introduced via this extension.
4.2. Server Hello 4.2. Server Hello
If the server receives a client hello that contains the If the server receives a client hello that contains the
'client_certificate_type' and 'server_certificate_type' extensions 'client_certificate_type' extension and/or the
and chooses a cipher suite then three outcomes are possible: 'server_certificate_type' extension then three outcomes are possible:
1. The server does not support the extension defined in this 1. The server does not support the extension defined in this
document. In this case the server returns the server hello document. In this case the server returns the server hello
without the extensions defined in this document. without the extensions defined in this document.
2. The server supports the extension defined in this document but it 2. The server supports the extension defined in this document but it
does not have a certificate type in common with the client. Then does not have any certificate type in common with the client.
the server terminates the session with a fatal alert of type Then, the server terminates the session with a fatal alert of
"unsupported_certificate". type "unsupported_certificate".
3. The server supports the extensions defined in this document and 3. The server supports the extensions defined in this document and
has at least one certificate type in common with the client. In has at least one certificate type in common with the client. In
this case the processing rules described below are followed. this case the processing rules described below are followed.
If the client hello indicates support of raw public keys in the The 'client_certificate_type' in the client hello indicates the
'client_certificate_type' extension and the server chooses to use raw certificate types the client is able to provide to the server, when
public keys then the TLS server MUST place the SubjectPublicKeyInfo requested using a certificate_request message. If the TLS server
structure into the Certificate payload. wants to request a certificate from the client (via the
certificate_request message) it MUST include the
If the TLS server also requests a certificate from the client (via 'client_certificate_type' extension in the server hello. This
the certificate_request message) it MUST include the 'client_certificate_type' in the server hello then indicates the type
'client_certificate_type' extension with a value chosen from the list of certificates the client is requested to provide in a subsequent
of client-supported certificates types (as provided in the certificate payload. The value conveyed in the
'client_certificate_type' of the client hello). 'client_certificate_type' MUST be selected from one of the values
provided in the 'client_certificate_type' extension sent in the
client hello. The server MUST also include a certificate_request
payload in the server hello message.
If the server does not send a certificate_request payload (for If the server does not send a certificate_request payload (for
example, because client authentication happens at the application example, because client authentication happens at the application
layer or no client authentication is required) or none of the layer or no client authentication is required) or none of the
certificates supported by the client (as indicated in the certificates supported by the client (as indicated in the
'server_certificate_type' in the client hello) match the server- 'client_certificate_type' in the client hello) match the server-
supported certificate types then the 'server_certificate_type' supported certificate types then the 'client_certificate_type'
payload in the server hello is omitted. payload in the server hello MUST be omitted.
The 'server_certificate_type' in the client hello indicates the types
of certificates the client is able to process when provided by the
server in a subsequent certificate payload. If the client hello
indicates support of raw public keys in the 'server_certificate_type'
extension and the server chooses to use raw public keys then the TLS
server MUST place the SubjectPublicKeyInfo structure into the
Certificate payload. With the 'server_certificate_type' in the
server hello the TLS server indicates the certificate type carried in
the Certificate payload. This additional indication allows to avoid
parsing ambiguities since the Certificate payload may contain either
the X.509 certificate or a SubjectPublicKeyInfo structure. Note that
only a single value is permitted in the 'server_certificate_type'
extension when carried in the server hello.
4.3. Client Authentication 4.3. Client Authentication
Authentication of the TLS client to the TLS server is supported only Authentication of the TLS client to the TLS server is supported only
through authentication of the received client SubjectPublicKeyInfo through authentication of the received client SubjectPublicKeyInfo
via an out-of-band method. via an out-of-band method.
5. Examples 5. Examples
This section illustrates a number of possible usage scenarios. Figure 6, Figure 7, and Figure 8 illustrate example exchanges. Note
that TLS ciphersuites using a Diffie-Hellman exchange offering
forward secrecy can be used with raw public keys although we do not
show the information exchange at that level with the subsequent
message flows.
5.1. TLS Server uses Raw Public Key 5.1. TLS Server uses Raw Public Key
This section shows an example where the TLS client indicates its This section shows an example where the TLS client indicates its
ability to receive and validate raw public keys from the server. In ability to receive and validate raw public keys from the server. In
our example the client is quite restricted since it is unable to our example the client is quite restricted since it is unable to
process other certificate types sent by the server. It also does not process other certificate types sent by the server. It also does not
have credentials (at the TLS layer) it could send to the server and have credentials at the TLS layer it could send to the server and
therefore omits the 'client_certificate_type' extension. Hence, the therefore omits the 'client_certificate_type' extension. Hence, the
client only populates the 'server_certificate_type' extension with client only populates the 'server_certificate_type' extension with
the raw public key type, as shown in [1]. the raw public key type, as shown in [1].
When the TLS server receives the client hello it processes the When the TLS server receives the client hello it processes the
extension. Since it has a raw public key it indicates in [2] that it extension. Since it has a raw public key it indicates in [2] that it
had chosen to place the SubjectPublicKeyInfo structure into the had chosen to place the SubjectPublicKeyInfo structure into the
Certificate payload [3]. Certificate payload [3].
The client uses this raw public key in the TLS handshake together The client uses this raw public key in the TLS handshake together
with an out-of-band validation technique, such as DANE, to verify it. with an out-of-band validation technique, such as DANE, to verify it.
client_hello, client_hello,
server_certificate_type=(RawPublicKey) // [1] server_certificate_type=(RawPublicKey) // [1]
-> ->
<- server_hello, <- server_hello,
server_certificate_type=(RawPublicKey), // [2] server_certificate_type=(RawPublicKey), // [2]
certificate, // [3] certificate, // [3]
server_key_exchange, server_key_exchange,
server_hello_done server_hello_done
client_key_exchange, client_key_exchange,
change_cipher_spec, change_cipher_spec,
finished -> finished ->
<- change_cipher_spec, <- change_cipher_spec,
finished finished
Application Data <-------> Application Data Application Data <-------> Application Data
Figure 6: Example with Raw Public Key provided by the TLS Server. Figure 6: Example with Raw Public Key provided by the TLS Server.
5.2. TLS Client and Server use Raw Public Keys 5.2. TLS Client and Server use Raw Public Keys
This section shows an example where the TLS client as well as the TLS This section shows an example where the TLS client as well as the TLS
server use raw public keys. This is a use case envisioned for smart server use raw public keys. This is one of the use case envisioned
object networking. The TLS client in this case is an embedded device for smart object networking. The TLS client in this case is an
that is configured with a raw public key for use with TLS and is also embedded device that is configured with a raw public key for use with
able to process raw public keys sent by the server. Therefore, it TLS and is also able to process raw public keys sent by the server.
indicates these capabilities in [1]. As in the previously shown Therefore, it indicates these capabilities in [1]. As in the
example the server fulfills the client's request, indicates this via previously shown example the server fulfills the client's request,
the "RawPublicKey" value in the server_certificate_type payload, and indicates this via the "RawPublicKey" value in the
provides a raw public key into the Certificate payload back to the server_certificate_type payload [2], and provides a raw public key
client (see [3]). The TLS server, however, demands client into the Certificate payload back to the client (see [3]). The TLS
authentication and therefore a certificate_request is added [4]. The server, however, demands client authentication and therefore a
certificate_type payload in [2] indicates that the TLS server accepts certificate_request is added [4]. The certificate_type payload in
raw public keys. The TLS client, who has a raw public key pre- [5] indicates that the TLS server accepts raw public keys. The TLS
provisioned, returns it in the Certificate payload [5] to the server. client, who has a raw public key pre-provisioned, returns it in the
Certificate payload [6] to the server.
client_hello, client_hello,
client_certificate_type=(RawPublicKey) // [1] client_certificate_type=(RawPublicKey) // [1]
server_certificate_type=(RawPublicKey) // [1] server_certificate_type=(RawPublicKey) // [1]
-> ->
<- server_hello, <- server_hello,
server_certificate_type=(RawPublicKey)//[2] server_certificate_type=(RawPublicKey)//[2]
certificate, // [3] certificate, // [3]
client_certificate_type=(RawPublicKey)//[4] client_certificate_type=(RawPublicKey)//[5]
certificate_request, // [4] certificate_request, // [4]
server_key_exchange, server_key_exchange,
server_hello_done server_hello_done
certificate, // [5] certificate, // [6]
client_key_exchange, client_key_exchange,
change_cipher_spec, change_cipher_spec,
finished -> finished ->
<- change_cipher_spec, <- change_cipher_spec,
finished finished
Application Data <-------> Application Data Application Data <-------> Application Data
Figure 7: Example with Raw Public Key provided by the TLS Server and Figure 7: Example with Raw Public Key provided by the TLS Server and
the Client. the Client.
5.3. Combined Usage of Raw Public Keys and X.509 Certificate 5.3. Combined Usage of Raw Public Keys and X.509 Certificate
This section shows an example combining raw public keys and X.509 This section shows an example combining raw public keys and X.509
certificates. The client uses a raw public key for client certificates. The client uses a raw public key for client
authentication but the server provides an X.509 certificate. This authentication and the server provides an X.509 certificate. This
exchange starts with the client indicating its ability to process exchange starts with the client indicating its ability to process
X.509 certificates provided by the server, and the ability to send X.509 certificates and raw public keys, if provided by the server.
raw public keys (see [1]). The server provides the X.509 certificate Additionally, the client indicates that is has a raw public key for
in [3] with the indication present in [2]. For client authentication client-side authentication (see [1]). The server provides the X.509
the server indicates in [4] that it selected the raw public key certificate in [3] with the indication present in [2]. For client
format and requests a certificate from the client in [5]. The TLS authentication the server indicates in [4] that it selected the raw
client provides a raw public key in [6] after receiving and public key format and requests a certificate from the client in [5].
The TLS client provides a raw public key in [6] after receiving and
processing the TLS server hello message. processing the TLS server hello message.
client_hello, client_hello,
server_certificate_type=(X.509) server_certificate_type=(X.509, RawPublicKey)
client_certificate_type=(RawPublicKey) // [1] client_certificate_type=(RawPublicKey) // [1]
-> ->
<- server_hello, <- server_hello,
server_certificate_type=(X.509)//[2] server_certificate_type=(X.509)//[2]
certificate, // [3] certificate, // [3]
client_certificate_type=(RawPublicKey)//[4] client_certificate_type=(RawPublicKey)//[4]
certificate_request, // [5] certificate_request, // [5]
server_key_exchange, server_key_exchange,
server_hello_done server_hello_done
certificate, // [6] certificate, // [6]
client_key_exchange, client_key_exchange,
change_cipher_spec, change_cipher_spec,
finished -> finished ->
<- change_cipher_spec,
finished
Application Data <-------> Application Data <- change_cipher_spec,
finished
Application Data <-------> Application Data
Figure 8: Hybrid Certificate Example. Figure 8: Hybrid Certificate Example.
6. Security Considerations 6. Security Considerations
The transmission of raw public keys, as described in this document, The transmission of raw public keys, as described in this document,
provides benefits by lowering the over-the-air transmission overhead provides benefits by lowering the over-the-air transmission overhead
since raw public keys are quite naturally smaller than an entire since raw public keys are naturally smaller than an entire
certificate. There are also advantages from a code size point of certificate. There are also advantages from a code size point of
view for parsing and processing these keys. The cryptographic view for parsing and processing these keys. The cryptographic
procedures for associating the public key with the possession of a procedures for associating the public key with the possession of a
private key also follows standard procedures. private key also follows standard procedures.
The main security challenge is, however, how to associate the public The main security challenge is, however, how to associate the public
key with a specific entity. Without a secure binding between key with a specific entity. Without a secure binding between
identity and key, the protocol will be vulnerable to masquerade and identifier and key, the protocol will be vulnerable to man-in-the-
man-in-the-middle attacks. This document assumes that such binding middle attacks. This document assumes that such binding can be made
can be made out-of-band and we list a few examples in Section 1. out-of-band and we list a few examples in Section 1. DANE [RFC6698]
DANE [RFC6698] offers one such approach. In order to address these offers one such approach. In order to address these vulnerabilities,
vulnerabilities, specifications that make use of the extension MUST specifications that make use of the extension need to specify how the
specify how the identity and public key are bound. In addition to identifier and public key are bound. In addition to ensuring the
ensuring the binding is done out-of-band an implementation also needs binding is done out-of-band an implementation also needs to check the
to check the status of that binding. status of that binding.
If public keys are obtained using DANE, these public keys are If public keys are obtained using DANE, these public keys are
authenticated via DNSSEC. Pre-configured keys is another out of authenticated via DNSSEC. Pre-configured keys is another out-of-band
band method for authenticating raw public keys. While pre- method for authenticating raw public keys. While pre-configured keys
configured keys are not suitable for a generic Web-based are not suitable for a generic Web-based e-commerce environment such
e-commerce environment such keys are a reasonable approach for keys are a reasonable approach for many smart object deployments
many smart object deployments where there is a close relationship where there is a close relationship between the software running on
between the software running on the device and the server-side the device and the server-side communication endpoint. Regardless of
communication endpoint. Regardless of the chosen mechanism for the chosen mechanism for out-of-band public key validation an
out-of-band public key validation an assessment of the most assessment of the most suitable approach has to be made prior to the
suitable approach has to be made prior to the start of a start of a deployment to ensure the security of the system.
deployment to ensure the security of the system.
A downgrading attack is another possibility for an adversary to gain An attacker might try to influence the handshake exchange to make the
advantages. Thereby, an attacker might try to influence the parties select different certificate types than they would normally
handshake exchange to make the parties select different certificate choose.
types than they would normally choose.
For this attack, an attacker must actively change one or more For this attack, an attacker must actively change one or more
handshake messages. If this occurs, the client and server will handshake messages. If this occurs, the client and server will
compute different values for the handshake message hashes. As a compute different values for the handshake message hashes. As a
result, the parties will not accept each others' Finished messages. result, the parties will not accept each others' Finished messages.
Without the master_secret, the attacker cannot repair the Finished Without the master_secret, the attacker cannot repair the Finished
messages, so the attack will be discovered. messages, so the attack will be discovered.
7. IANA Considerations 7. IANA Considerations
skipping to change at page 12, line 40 skipping to change at page 14, line 10
substantially shaped the document and we would like to thank the substantially shaped the document and we would like to thank the
meeting participants for their input. The support for hashes of meeting participants for their input. The support for hashes of
public keys has been moved to [I-D.ietf-tls-cached-info] after the public keys has been moved to [I-D.ietf-tls-cached-info] after the
discussions at the IETF#82 meeting. discussions at the IETF#82 meeting.
We would like to thank the following persons for their review We would like to thank the following persons for their review
comments: Martin Rex, Bill Frantz, Zach Shelby, Carsten Bormann, comments: Martin Rex, Bill Frantz, Zach Shelby, Carsten Bormann,
Cullen Jennings, Rene Struik, Alper Yegin, Jim Schaad, Barry Leiba, Cullen Jennings, Rene Struik, Alper Yegin, Jim Schaad, Barry Leiba,
Paul Hoffman, Robert Cragie, Nikos Mavrogiannopoulos, Phil Hunt, John Paul Hoffman, Robert Cragie, Nikos Mavrogiannopoulos, Phil Hunt, John
Bradley, Klaus Hartke, Stefan Jucker, Kovatsch Matthias, Daniel Kahn Bradley, Klaus Hartke, Stefan Jucker, Kovatsch Matthias, Daniel Kahn
Gillmor, Peter Sylvester, Hauke Mehrtens, Alexey Melnikov, and James Gillmor, Peter Sylvester, Hauke Mehrtens, Alexey Melnikov, Stephen
Manger. Nikos Mavrogiannopoulos contributed the design for re-using Farrell, Richard Barnes, and James Manger. Nikos Mavrogiannopoulos
the certificate type registry. Barry Leiba contributed guidance for contributed the design for re-using the certificate type registry.
the IANA consideration text. Stefan Jucker, Kovatsch Matthias, and Barry Leiba contributed guidance for the IANA consideration text.
Klaus Hartke provided implementation feedback regarding the Stefan Jucker, Kovatsch Matthias, and Klaus Hartke provided
SubjectPublicKeyInfo structure. implementation feedback regarding the SubjectPublicKeyInfo structure.
Christer Holmberg provided the General Area (Gen-Art) review, Yaron Christer Holmberg provided the General Area (Gen-Art) review, Yaron
Sheffer provided the Security Directorate (SecDir) review, Bert Sheffer provided the Security Directorate (SecDir) review, Bert
Greevenbosch provided the Applications Area Directorate review, and Greevenbosch provided the Applications Area Directorate review, and
Linda Dunbar provided the Operations Directorate review. Linda Dunbar provided the Operations Directorate review.
We would like to thank our TLS working group chairs, Eric Rescorla We would like to thank our TLS working group chairs, Eric Rescorla
and Joe Salowey, for their guidance and support. Finally, we would and Joe Salowey, for their guidance and support. Finally, we would
like to thank Sean Turner, who is the responsible security area like to thank Sean Turner, who is the responsible security area
director for this work for his review comments and suggestions. director for this work for his review comments and suggestions.
9. References 9. References
9.1. Normative References 9.1. Normative References
[PKIX] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, May 2008.
[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.
[RFC3279] Bassham, L., Polk, W., and R. Housley, "Algorithms and [RFC3279] Bassham, L., Polk, W., and R. Housley, "Algorithms and
Identifiers for the Internet X.509 Public Key Identifiers for the Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 3279, April 2002. (CRL) Profile", RFC 3279, April 2002.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008. (TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, May 2008.
[RFC5480] Turner, S., Brown, D., Yiu, K., Housley, R., and T. Polk, [RFC5480] Turner, S., Brown, D., Yiu, K., Housley, R., and T. Polk,
"Elliptic Curve Cryptography Subject Public Key "Elliptic Curve Cryptography Subject Public Key
Information", RFC 5480, March 2009. Information", RFC 5480, March 2009.
[TLS-Certificate-Types-Registry] [TLS-Certificate-Types-Registry]
, "TLS Certificate Types Registry", February 2013, <http:/ "TLS Certificate Types Registry", February 2013,
/www.iana.org/assignments/tls-extensiontype-values#tls- <http://www.iana.org/assignments/
extensiontype-values-2>. tls-extensiontype-values#tls-extensiontype-values-2>.
[X.690] ITU, "ITU-T Recommendation X.690 (2002) | ISO/IEC [X.690] "Information technology - ASN.1 encoding rules: >
8825-1:2002, Information technology - ASN.1 encoding Specification of Basic Encoding Rules (BER), Canonical >
rules: Specification of Basic Encoding Rules (BER), Encoding Rules (CER) and Distinguished Encoding Rules >
Canonical Encoding Rules (CER) and Distinguished Encoding (DER).", RFC 5280, 2002.
Rules (DER)", 2002.
9.2. Informative References 9.2. Informative References
[ASN.1-Dump] [ASN.1-Dump]
Gutmann, P., "ASN.1 Object Dump Program", February 2013, Gutmann, P., "ASN.1 Object Dump Program", February 2013,
<http://www.cs.auckland.ac.nz/~pgut001/>. <http://www.cs.auckland.ac.nz/~pgut001/>.
[Defeating-SSL] [Defeating-SSL]
Marlinspike, M., "New Tricks for Defeating SSL in Marlinspike, M., "New Tricks for Defeating SSL in
Practice", February 2009, <http://www.blackhat.com/ Practice", February 2009, <http://www.blackhat.com/
presentations/bh-dc-09/Marlinspike/BlackHat-DC-09 presentations/bh-dc-09/Marlinspike/
-Marlinspike-Defeating-SSL.pdf>. BlackHat-DC-09-Marlinspike-Defeating-SSL.pdf>.
[I-D.ietf-core-coap] [I-D.ietf-core-coap]
Shelby, Z., Hartke, K., and C. Bormann, "Constrained Shelby, Z., Hartke, K., and C. Bormann, "Constrained
Application Protocol (CoAP)", draft-ietf-core-coap-18 Application Protocol (CoAP)", draft-ietf-core-coap-18
(work in progress), June 2013. (work in progress), June 2013.
[I-D.ietf-tls-cached-info] [I-D.ietf-tls-cached-info]
Santesson, S. and H. Tschofenig, "Transport Layer Security Santesson, S. and H. Tschofenig, "Transport Layer Security
(TLS) Cached Information Extension", draft-ietf-tls- (TLS) Cached Information Extension", draft-ietf-tls-
cached-info-15 (work in progress), October 2013. cached-info-15 (work in progress), October 2013.
[RFC4511] Sermersheim, J., "Lightweight Directory Access Protocol [LDAP] Sermersheim, J., "Lightweight Directory Access Protocol
(LDAP): The Protocol", RFC 4511, June 2006. (LDAP): The Protocol", RFC 4511, June 2006.
[RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication [RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
of Named Entities (DANE) Transport Layer Security (TLS) of Named Entities (DANE) Transport Layer Security (TLS)
Protocol: TLSA", RFC 6698, August 2012. Protocol: TLSA", RFC 6698, August 2012.
Appendix A. Example Encoding Appendix A. Example Encoding
The following example hex sequence describes a SubjectPublicKeyInfo For example, the hex sequence shown in Figure 9 describes a
structure inside the certificate payload: SubjectPublicKeyInfo structure inside the certificate payload.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9
---+------+-----+-----+-----+-----+-----+-----+-----+-----+----- +------+-----+-----+-----+-----+-----+-----+-----+-----+-----
1 | 0x30, 0x81, 0x9f, 0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 1 | 0x30, 0x81, 0x9f, 0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48,
2 | 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x01, 0x05, 0x00, 0x03, 0x81, 2 | 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x01, 0x05, 0x00, 0x03, 0x81,
3 | 0x8d, 0x00, 0x30, 0x81, 0x89, 0x02, 0x81, 0x81, 0x00, 0xcd, 3 | 0x8d, 0x00, 0x30, 0x81, 0x89, 0x02, 0x81, 0x81, 0x00, 0xcd,
4 | 0xfd, 0x89, 0x48, 0xbe, 0x36, 0xb9, 0x95, 0x76, 0xd4, 0x13, 4 | 0xfd, 0x89, 0x48, 0xbe, 0x36, 0xb9, 0x95, 0x76, 0xd4, 0x13,
5 | 0x30, 0x0e, 0xbf, 0xb2, 0xed, 0x67, 0x0a, 0xc0, 0x16, 0x3f, 5 | 0x30, 0x0e, 0xbf, 0xb2, 0xed, 0x67, 0x0a, 0xc0, 0x16, 0x3f,
6 | 0x51, 0x09, 0x9d, 0x29, 0x2f, 0xb2, 0x6d, 0x3f, 0x3e, 0x6c, 6 | 0x51, 0x09, 0x9d, 0x29, 0x2f, 0xb2, 0x6d, 0x3f, 0x3e, 0x6c,
7 | 0x2f, 0x90, 0x80, 0xa1, 0x71, 0xdf, 0xbe, 0x38, 0xc5, 0xcb, 7 | 0x2f, 0x90, 0x80, 0xa1, 0x71, 0xdf, 0xbe, 0x38, 0xc5, 0xcb,
8 | 0xa9, 0x9a, 0x40, 0x14, 0x90, 0x0a, 0xf9, 0xb7, 0x07, 0x0b, 8 | 0xa9, 0x9a, 0x40, 0x14, 0x90, 0x0a, 0xf9, 0xb7, 0x07, 0x0b,
9 | 0xe1, 0xda, 0xe7, 0x09, 0xbf, 0x0d, 0x57, 0x41, 0x86, 0x60, 9 | 0xe1, 0xda, 0xe7, 0x09, 0xbf, 0x0d, 0x57, 0x41, 0x86, 0x60,
10 | 0xa1, 0xc1, 0x27, 0x91, 0x5b, 0x0a, 0x98, 0x46, 0x1b, 0xf6, 10 | 0xa1, 0xc1, 0x27, 0x91, 0x5b, 0x0a, 0x98, 0x46, 0x1b, 0xf6,
11 | 0xa2, 0x84, 0xf8, 0x65, 0xc7, 0xce, 0x2d, 0x96, 0x17, 0xaa, 11 | 0xa2, 0x84, 0xf8, 0x65, 0xc7, 0xce, 0x2d, 0x96, 0x17, 0xaa,
12 | 0x91, 0xf8, 0x61, 0x04, 0x50, 0x70, 0xeb, 0xb4, 0x43, 0xb7, 12 | 0x91, 0xf8, 0x61, 0x04, 0x50, 0x70, 0xeb, 0xb4, 0x43, 0xb7,
13 | 0xdc, 0x9a, 0xcc, 0x31, 0x01, 0x14, 0xd4, 0xcd, 0xcc, 0xc2, 13 | 0xdc, 0x9a, 0xcc, 0x31, 0x01, 0x14, 0xd4, 0xcd, 0xcc, 0xc2,
14 | 0x37, 0x6d, 0x69, 0x82, 0xd6, 0xc6, 0xc4, 0xbe, 0xf2, 0x34, 14 | 0x37, 0x6d, 0x69, 0x82, 0xd6, 0xc6, 0xc4, 0xbe, 0xf2, 0x34,
15 | 0xa5, 0xc9, 0xa6, 0x19, 0x53, 0x32, 0x7a, 0x86, 0x0e, 0x91, 15 | 0xa5, 0xc9, 0xa6, 0x19, 0x53, 0x32, 0x7a, 0x86, 0x0e, 0x91,
16 | 0x82, 0x0f, 0xa1, 0x42, 0x54, 0xaa, 0x01, 0x02, 0x03, 0x01, 16 | 0x82, 0x0f, 0xa1, 0x42, 0x54, 0xaa, 0x01, 0x02, 0x03, 0x01,
17 | 0x00, 0x01 17 | 0x00, 0x01
Figure 9: Example SubjectPublicKeyInfo Structure Byte Sequence. Figure 9: Example SubjectPublicKeyInfo Structure Byte Sequence.
We used Peter Gutmann's ASN.1 decoder [ASN.1-Dump] to turn the above- The decoded byte-sequence shown in Figure 9 (for example using
shown byte-sequence into an ASN.1 structure, as shown in of the Peter's ASN.1 decoder [ASN.1-Dump]) illustrates the structure, as
Figure 10. shown in Figure 10.
Offset Length Description Offset Length Description
------------------------------------------------------------------- -------------------------------------------------------------------
0 3+159: SEQUENCE { 0 3+159: SEQUENCE {
3 2+13: SEQUENCE { 3 2+13: SEQUENCE {
5 2+9: OBJECT IDENTIFIER Value (1 2 840 113549 1 1 1) 5 2+9: OBJECT IDENTIFIER Value (1 2 840 113549 1 1 1)
: PKCS #1, rsaEncryption : PKCS #1, rsaEncryption
16 2+0: NULL 16 2+0: NULL
: } : }
18 3+141: BIT STRING, encapsulates { 18 3+141: BIT STRING, encapsulates {
skipping to change at page 16, line 4 skipping to change at page 17, line 11
: } : }
Figure 10: Decoding of Example SubjectPublicKeyInfo Structure. Figure 10: Decoding of Example SubjectPublicKeyInfo Structure.
Authors' Addresses Authors' Addresses
Paul Wouters (editor) Paul Wouters (editor)
Red Hat Red Hat
Email: paul@nohats.ca Email: paul@nohats.ca
Hannes Tschofenig (editor) Hannes Tschofenig (editor)
Nokia Solutions and Networks Cambridge CBI 9NJ
Linnoitustie 6 UK
Espoo 02600
Finland
Phone: +358 (50) 4871445
Email: Hannes.Tschofenig@gmx.net Email: Hannes.Tschofenig@gmx.net
URI: http://www.tschofenig.priv.at URI: http://www.tschofenig.priv.at
John Gilmore John Gilmore
PO Box 170608 PO Box 170608
San Francisco, California 94117 San Francisco, California 94117
USA USA
Phone: +1 415 221 6524 Phone: +1 415 221 6524
Email: gnu@toad.com Email: gnu@toad.com
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