draft-ietf-secsh-publickey-subsystem-01.txt   draft-ietf-secsh-publickey-subsystem-02.txt 
Secure Shell Working Group J. Galbraith Secure Shell Working Group J. Galbraith
Internet-Draft J. Van Dyke Internet-Draft J. Van Dyke
Expires: October 1, 2004 B. McClure Expires: September 18, 2005 B. McClure
VanDyke Software VanDyke Software
J. Bright J. Bright
Silicon Circus Silicon Circus
April 2, 2004 March 17, 2005
Secure Shell Public-Key Subsystem Secure Shell Public-Key Subsystem
draft-ietf-secsh-publickey-subsystem-01.txt draft-ietf-secsh-publickey-subsystem-02.txt
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved. Copyright (C) The Internet Society (2005).
Abstract Abstract
SECSH defines an authentication mechanism that is based on public SECSH defines an authentication mechanism that is based on public
keys, but does not define any mechanism for key distribution. No keys, but does not define any mechanism for key distribution. No
common key management solution exists in current implementations. common key management solution exists in current implementations.
This document describes a protocol that can be used to configure This document describes a protocol that can be used to configure
public keys in an implementation-independent fashion, allowing client public keys in an implementation-independent fashion, allowing client
software to take on the burden of this configuration. software to take on the burden of this configuration.
This protocol is intended to be used from the Secure Shell Connection This protocol is intended to be used from the Secure Shell Connection
Protocol [4] as a subsystem, as described in Section ``Starting a Protocol [4] as a subsystem, as described in the Section "Starting a
Shell or a Command''. The subsystem name used with this protocol is Shell or a Command". The subsystem name used with this protocol is
"publickey". "publickey".
The public-key subsystem provides a server-independent mechanism for The public-key subsystem provides a server-independent mechanism for
clients to add public keys, remove public keys, and list the current clients to add public keys, remove public keys, and list the current
public keys known by the server. Rights to manage public keys are public keys known by the server. Rights to manage public keys are
specific and limited to the authenticated user. specific and limited to the authenticated user.
A public key may also be associated with various restrictions, A public key may also be associated with various restrictions,
including a mandatory command or subsystem. including a mandatory command or subsystem.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Public-Key Subsystem Overview . . . . . . . . . . . . . . . 4 2. Public-Key Subsystem Overview . . . . . . . . . . . . . . . . 5
2.1 Opening the Public-Key Subsystem . . . . . . . . . . . . . . 4 2.1 Opening the Public-Key Subsystem . . . . . . . . . . . . . 5
2.2 Requests . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 Requests . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Responses . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3 Responses . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3.1 The Status Response . . . . . . . . . . . . . . . . . . . . 5 2.3.1 The Status Response . . . . . . . . . . . . . . . . . 6
3. Public-Key Subsystem Operations . . . . . . . . . . . . . . 7 3. Public-Key Subsystem Operations . . . . . . . . . . . . . . . 8
3.1 Version Packet . . . . . . . . . . . . . . . . . . . . . . . 7 3.1 Version Packet . . . . . . . . . . . . . . . . . . . . . . 8
3.2 Adding a public key . . . . . . . . . . . . . . . . . . . . 7 3.2 Adding a public key . . . . . . . . . . . . . . . . . . . 8
3.3 Removing a public key . . . . . . . . . . . . . . . . . . . 10 3.3 Removing a public key . . . . . . . . . . . . . . . . . . 11
3.4 Listing public keys . . . . . . . . . . . . . . . . . . . . 10 3.4 Listing public keys . . . . . . . . . . . . . . . . . . . 11
3.5 Listing server capabilities . . . . . . . . . . . . . . . . 10 3.5 Listing server capabilities . . . . . . . . . . . . . . . 11
4. Security Considerations . . . . . . . . . . . . . . . . . . 12 4. Security Considerations . . . . . . . . . . . . . . . . . . . 13
Normative References . . . . . . . . . . . . . . . . . . . . 13 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 13 5.1 Registrations . . . . . . . . . . . . . . . . . . . . . . 14
Intellectual Property and Copyright Statements . . . . . . . 15 5.2 Names . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.2.1 Conventions for Names . . . . . . . . . . . . . . . . 14
5.2.2 Future Assignments of Names . . . . . . . . . . . . . 14
5.3 Request names . . . . . . . . . . . . . . . . . . . . . . 15
5.4 Response names . . . . . . . . . . . . . . . . . . . . . . 15
5.5 Attribute names . . . . . . . . . . . . . . . . . . . . . 15
5.6 Status codes . . . . . . . . . . . . . . . . . . . . . . . 16
5.6.1 Conventions . . . . . . . . . . . . . . . . . . . . . 16
5.6.2 Initial Assignments . . . . . . . . . . . . . . . . . 16
5.6.3 Future Assignments . . . . . . . . . . . . . . . . . . 16
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.1 Normative References . . . . . . . . . . . . . . . . . . . 17
6.2 Informative References . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 17
Intellectual Property and Copyright Statements . . . . . . . . 19
1. Introduction 1. Introduction
SECSH is a protocol for secure remote login and other secure network SECSH is a protocol for secure remote login and other secure network
services over an insecure network. SECSH defines an authentication services over an insecure network. SECSH defines an authentication
mechanism that is based on public keys, but does not define any mechanism that is based on public keys, but does not define any
mechanism for key distribution. Common practice is to authenticate mechanism for key distribution. Common practice is to authenticate
once with password authentication and transfer the public key to the once with password authentication and transfer the public key to the
server. However, to date no two implementations use the same server. However, to date no two implementations use the same
mechanism to configure a public key for use. mechanism to configure a public key for use.
skipping to change at page 7, line 8 skipping to change at page 8, line 8
SSH_PUBLICKEY_VERSION_NOT_SUPPORTED 3 SSH_PUBLICKEY_VERSION_NOT_SUPPORTED 3
SSH_PUBLICKEY_KEY_NOT_FOUND 4 SSH_PUBLICKEY_KEY_NOT_FOUND 4
SSH_PUBLICKEY_KEY_NOT_SUPPORTED 5 SSH_PUBLICKEY_KEY_NOT_SUPPORTED 5
SSH_PUBLICKEY_KEY_ALREADY_PRESENT 6 SSH_PUBLICKEY_KEY_ALREADY_PRESENT 6
SSH_PUBLICKEY_GENERAL_FAILURE 7 SSH_PUBLICKEY_GENERAL_FAILURE 7
SSH_PUBLICKEY_REQUEST_NOT_SUPPORTED 8 SSH_PUBLICKEY_REQUEST_NOT_SUPPORTED 8
3. Public-Key Subsystem Operations 3. Public-Key Subsystem Operations
The public-key subsystem currently defines four operations: add, The public-key subsystem currently defines four operations: add,
remove, list, and command. remove, list, and listattributes.
3.1 Version Packet 3.1 Version Packet
Both sides MUST start by sending a version packet that indicates the Both sides MUST start by sending a version packet that indicates the
version of the protocol they are using. version of the protocol they are using.
string "version" string "version"
uint32 protocol-version-number uint32 protocol-version-number
The version of the protocol described by this document is version 2. The version of the protocol described by this document is version 2.
Both sides send the highest version that they implement. The lower of Both sides send the highest version that they implement. The lower
the version numbers is the version of the protocol to use. If either of the version numbers is the version of the protocol to use. If
side can't support the lower version, it should close the subsystem either side can't support the lower version, it should close the
and notify the other side by sending an SSH_MSG_CHANNEL_CLOSE subsystem and notify the other side by sending an
message. Before closing the subsystem, a status message with the SSH_MSG_CHANNEL_CLOSE message. Before closing the subsystem, a
status SSH_PUBLICKEY_VERSION_NOT_SUPPORTED SHOULD be sent. status message with the status SSH_PUBLICKEY_VERSION_NOT_SUPPORTED
SHOULD be sent.
Both sides MUST wait to receive this version before continuing. Both sides MUST wait to receive this version before continuing. The
"version" packet MUST NOT be sent again after this initial exchange.
3.2 Adding a public key 3.2 Adding a public key
If the client wishes to add a public key, the client sends: If the client wishes to add a public key, the client sends:
string "add" string "add"
string public-key algorithm name string public-key algorithm name
string public-key blob string public-key blob
boolean overwrite boolean overwrite
uint32 attribute-count uint32 attribute-count
skipping to change at page 13, line 5 skipping to change at page 14, line 5
for the new key than were previously present. Servers should take for the new key than were previously present. Servers should take
care that when doing this, clients are not able to override presets care that when doing this, clients are not able to override presets
from the server's administrator. from the server's administrator.
This protocol requires the client to assume that the server will This protocol requires the client to assume that the server will
correctly implement and observe attributes applied to keys. correctly implement and observe attributes applied to keys.
Implementation errors in the server could cause clients to authorise Implementation errors in the server could cause clients to authorise
keys for access they were not intended to have, or to apply fewer keys for access they were not intended to have, or to apply fewer
restrictions than were intended. restrictions than were intended.
Normative References 5. IANA Considerations
[1] Ylonen, T., Kivinen, T., Saarinen, M., Rinne, T. and S. This section contains conventions used in naming the namespaces, the
Lehtinen, "SSH Protocol Architecture", initial state of the registry, and instructions for future
draft-ietf-secsh-architecture-13 (work in progress), January assignments.
2002.
[2] Ylonen, T., Kivinen, T., Saarinen, M., Rinne, T. and S. 5.1 Registrations
Lehtinen, "SSH Transport Layer Protocol",
draft-ietf-secsh-transport-15 (work in progress), March 2002.
[3] Ylonen, T., Kivinen, T., Saarinen, M., Rinne, T. and S. Consistent with section 7 of [1], this document makes the following
Lehtinen, "SSH Authentication Protocol", registration:
draft-ietf-secsh-userauth-16 (work in progress), February 2002.
[4] Ylonen, T., Kivinen, T., Saarinen, M., Rinne, T. and S. The subsystem name "publickey".
Lehtinen, "SSH Connection Protocol", draft-ietf-secsh-connect-16
(work in progress), January 2002.
[5] Alvestrand, H., "Tags for the Identification of Languages", RFC 5.2 Names
1766, March 1995.
[6] Yergeau, F., "UTF-8, a transformation format of ISO 10646", RFC In the following sections, the values for the name spaces are
2279, January 1998. textual. The conventions and instructions to the IANA for future
assignments are given in this section. The initial assignments are
given in their respective sections.
5.2.1 Conventions for Names
All names registered by the IANA in the following sections MUST be
printable US-ASCII strings, and MUST NOT contain the characters
at-sign ("@"), comma (","), or whitespace or control characters
(ASCII codes 32 or less). Names are case-sensitive, and MUST NOT be
longer than 64 characters.
A provision is made here for locally extensible names. The IANA will
not register, and will not control names with the at-sign in them.
Names with the at-sign in them will have the format of
"name@domainname" (without the double quotes) where the part
preceeding the at-sign is the name. The format of the part preceding
the at-sign is not specified, however these names MUST be printable
US-ASCII strings, and MUST NOT contain the comma character (","), or
whitespace, or control characters (ASCII codes 32 or less). The part
following the at-sign MUST be a valid, fully qualified internet
domain name [8] controlled by the person or organization defining the
name. Names are case-sensitive, and MUST NOT be longer than 64
characters. It is up to each domain how it manages its local
namespace. It has been noted that these names resemble STD 11 [7]
email addresses. This is purely coincidental and actually has
nothing to do with STD 11 [7]. An example of a locally defined name
is "ourcipher-cbc@example.com" (without the double quotes).
5.2.2 Future Assignments of Names
Requests for assignments of new Names MUST be done through the IETF
CONSENSUS method as described in [9].
5.3 Request names
The following table lists the initial assignments of Request names
Request Name
-------------
version
add
remove
list
listattributes
5.4 Response names
The following table lists the initial assignments of Response names
Response Name
--------------
version
status
publickey
attribute
5.5 Attribute names
Attributes are used to define properties or restrictions for public
keys. The following table lists the initial assignments of Response
names
Attribute Name
---------------
comment
comment-language
command-override
subsystem
x11
shell
exec
agent
env
from
port-forward
reverse-forward
5.6 Status codes
The status code is a byte value, describing the status of a request.
5.6.1 Conventions
Status responses have status codes in the range 0 to 255. These
numbers are allocated as follows. Of these, the range 192 to 255 is
reserved for use by local, private extensions.
5.6.2 Initial Assignments
The following table identifies the initial assignments of the status
code values.
Status code Value Reference
------------ ----- ---------
SSH_PUBLICKEY_SUCCESS 0
SSH_PUBLICKEY_ACCESS_DENIED 1
SSH_PUBLICKEY_STORAGE_EXCEEDED 2
SSH_PUBLICKEY_VERSION_NOT_SUPPORTED 3
SSH_PUBLICKEY_KEY_NOT_FOUND 4
SSH_PUBLICKEY_KEY_NOT_SUPPORTED 5
SSH_PUBLICKEY_KEY_ALREADY_PRESENT 6
SSH_PUBLICKEY_GENERAL_FAILURE 7
SSH_PUBLICKEY_REQUEST_NOT_SUPPORTED 8
5.6.3 Future Assignments
Requests for assignments of new message numbers in the range of 0 to
191 MUST be done through the STANDARDS ACTION method as described in
[9].
The IANA will not control the message numbers range of 192 through
255. This range will be left for PRIVATE USE.
6. References
6.1 Normative References
[1] Lonvick, C., "SSH Protocol Architecture",
Internet-Draft draft-ietf-secsh-architecture-22, March 2005.
[2] Lonvick, C., "SSH Transport Layer Protocol",
Internet-Draft draft-ietf-secsh-transport-24, March 2005.
[3] Lonvick, C., "SSH Authentication Protocol",
Internet-Draft draft-ietf-secsh-userauth-27, March 2005.
[4] Lonvick, C., "SSH Connection Protocol",
Internet-Draft draft-ietf-secsh-connect-25, March 2005.
[5] Alvestrand, H., "Tags for the Identification of Languages",
RFC 1766, March 1995.
[6] Yergeau, F., "UTF-8, a transformation format of ISO 10646",
RFC 2279, January 1998.
6.2 Informative References
[7] Crocker, D., "Standard for the format of ARPA Internet text
messages", STD 11, RFC 822, August 1982.
[8] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987.
[9] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.
Authors' Addresses Authors' Addresses
Joseph Galbraith Joseph Galbraith
VanDyke Software VanDyke Software
4848 Tramway Ridge Blvd 4848 Tramway Ridge Blvd
Suite 101 Suite 101
Albuquerque, NM 87111 Albuquerque, NM 87111
US US
Phone: +1 505 332 5700 Phone: +1 505 332 5700
EMail: galb-list@vandyke.com Email: galb-list@vandyke.com
Jeff P. Van Dyke Jeff P. Van Dyke
VanDyke Software VanDyke Software
4848 Tramway Ridge Blvd 4848 Tramway Ridge Blvd
Suite 101 Suite 101
Albuquerque, NM 87111 Albuquerque, NM 87111
US US
Phone: +1 505 332 5700 Phone: +1 505 332 5700
EMail: jpv@vandyke.com Email: jpv@vandyke.com
Brent McClure Brent McClure
VanDyke Software VanDyke Software
4848 Tramway Ridge Blvd 4848 Tramway Ridge Blvd
Suite 101 Suite 101
Albuquerque, NM 87111 Albuquerque, NM 87111
US US
Phone: +1 505 332 5700 Phone: +1 505 332 5700
EMail: bdm@vandyke.com Email: bdm@vandyke.com
Jon Bright Jon Bright
Silicon Circus Silicon Circus
24 Jubilee Road 24 Jubilee Road
Chichester, West Sussex PO19 7XB Chichester, West Sussex PO19 7XB
UK UK
Phone: +49 172 524 0521 Phone: +49 172 524 0521
EMail: jon@siliconcircus.com Email: jon@siliconcircus.com
Trademark notice
"ssh" is a registered trademark in the United States and/or other
countries.
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