Internet Engineering Task Force T. Chu
Internet-Draft M. Hamrick
Intended status: Standards Track M. Lentczner
Expires: January 13, 2010 Linden Research, Inc.
July 12, 2009
Open Grid Protocol: Service Establishment
draft-hamrick-ogp-auth-01
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Abstract
Service establishment in the Open Grid Protocol is the process of
creating an application layer association between a client
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application and a remote service responsible for managing an end
entity's identity. Before a service may be used, the requesting
party must present credentials, handle any per-entity authentication-
time maintenance requirements, and request capabilities the client
intends to use. Peer hosts to be authenticated include end users and
remote domain hosts. Multiple mechanisms are defined for
authentication, but all authentication and service establishment
requests follow the same pattern.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. The Service Establishment Pattern . . . . . . . . . . . . . . 4
2.1. Authentication . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Maintenance . . . . . . . . . . . . . . . . . . . . . . . 6
2.3. Capability Request / Provisioning . . . . . . . . . . . . 7
3. Authentication Mechanisms . . . . . . . . . . . . . . . . . . 8
3.1. User Authentication . . . . . . . . . . . . . . . . . . . 8
3.1.1. Preconditions . . . . . . . . . . . . . . . . . . . . 8
3.1.1.1. Client Preconditions . . . . . . . . . . . . . . . 8
3.1.1.2. Agent Domain Preconditions . . . . . . . . . . . . 8
3.1.2. Postconditions . . . . . . . . . . . . . . . . . . . . 8
3.1.2.1. Client Postconditions . . . . . . . . . . . . . . 8
3.1.2.2. Agent Domain Postconditions . . . . . . . . . . . 9
3.1.3. Side Effects . . . . . . . . . . . . . . . . . . . . . 9
3.1.4. Sequence of Events . . . . . . . . . . . . . . . . . . 9
3.2. Peer Authentication using a TLS Client Certificate . . . . 11
3.3. Peer Authentication using OAuth . . . . . . . . . . . . . 11
4. Agent Login (Resource Class) . . . . . . . . . . . . . . . . . 12
4.1. Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.1.1. Agent Identifier . . . . . . . . . . . . . . . . . . . 12
4.1.2. Account Identifier . . . . . . . . . . . . . . . . . . 12
4.1.3. Hashed Password Authenticator . . . . . . . . . . . . 12
4.1.4. Challenge-Response Authenticator . . . . . . . . . . . 12
4.1.5. PKCS#5 PBKDF2 Authenticator . . . . . . . . . . . . . 13
4.2. Response . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.2.1. Success . . . . . . . . . . . . . . . . . . . . . . . 14
4.2.2. Maintenance Deferred Success . . . . . . . . . . . . . 14
4.2.3. Authentication Non-Success . . . . . . . . . . . . . . 14
4.3. Errors and Exceptions . . . . . . . . . . . . . . . . . . 14
4.3.1. Authentication Failure . . . . . . . . . . . . . . . . 14
4.3.2. Agent Selection Failure . . . . . . . . . . . . . . . 14
4.3.3. "User Intervention Required" Failure . . . . . . . . . 14
4.3.4. "Non Specific" Failure . . . . . . . . . . . . . . . . 15
4.4. Interface (POST) . . . . . . . . . . . . . . . . . . . . . 15
5. Login-Time Maintenance (Resource Class) . . . . . . . . . . . 17
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5.1. Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.2. Response . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.3. Interface (GET) . . . . . . . . . . . . . . . . . . . . . 18
6. Security Considerations . . . . . . . . . . . . . . . . . . . 19
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.1. Normative References . . . . . . . . . . . . . . . . . . . 19
8.2. Informative References . . . . . . . . . . . . . . . . . . 20
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20
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1. Introduction
The "service establishment pattern" is an abstract sequence used to
describe the process of creating an application layer association
between a client application and a service implementing some aspect
of the virtual world. There are three steps in service
establishment: authentication, maintenance and capability request /
provisioning. Several mechanisms for authenticating application
layer entities are defined. Maintenance is an optional step for
service providers (though client applications MUST support it.) The
final step in the service establishment pattern is the client's
requests for a specific set of capabilities to perform actions on
sensitive resources and the service's grant of those capabilities.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. The Service Establishment Pattern
Three scenarios exist for sensitive resource access in the virtual
world:
o A user presents credentials to an agent domain to demonstrate
their right to control a specific avatar.
o A domain requests general access to services offered by a peer
domain.
o And a domain requests access to a sensitive resource owned by a
user, maintained by a peer domain.
The three common service establishment steps are present in each of
these scenarios: authentication, maintenance and capability request /
provisioning.
2.1. Authentication
Authentication is the first step in associating a client application
with a service. Before a client may interact with a remote service,
it must authenticate itself by presenting credentials demonstrating
its right to access sensitive resources maintained by the service.
Authentication is the process of presenting the client's "Identifier"
and "Authenticator" to the service.
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It should be noted that a remote service may maintain public, non-
sensitive resources. "Authentication" in this case is still
required, if for no other reason than to establish a unique
application layer session. If a client requests access to non-
sensitive information, the server MAY choose to ignore the
authenticator presented in the authentication phase.
Authentication begins by requesting the agent_login resource from a
well-known URL. [I-D.hamrick-llsd] The service managing this
resource then makes an access control decision based on the verity of
the credential The result of this authentication, whether success or
failure, it is returned to the client application via a LLSD message.
The content and form of these messages are provided below as an LLIDL
interface.
The client authentication process results in one of seven classes of
response from the service:
o success
o deferred success due to maintenance
o authentication non-success due to missing secret
o authentication failure
o agent selection failure
o "user intervention required" failure, and
o "non-specified" failure.
Responses to authentication requests are successes, non-successes and
failures. A "success" indicates the client application should have
enough information to progress past the authentication phase and
begin using the service. A "deferred success" implies use of the
system will continue after a "short" period. In either case, the
agent domain does not expect the client application to re-submit the
agent_login request. Authentication "non-success" results from a
client requesting per-agent or per-account authentication parameters.
After sending a "non-success", the agent domain expects the client to
resubmit the agent_login request "shortly." Failures of all type
indicate the agent domain believes a condition exists requiring
explicit user intervention. In the case of an authentication
failure, the user should either retry the authentication request or
recover their password. A failure due to "user intervention
required" indicates the agent domain believes the user's account is
in a state that required "out of band" recovery. Reading and
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accepting the agent domain's Terms of Service or Critical Messages
are examples of recovering from "user intervention required"
failures. Non-Specified failures indicate a non-recoverable problem
that is not defined in this specification.
Client applications may authenticate using an "Account Identifier" or
an "Agent Identifier". Either type of identifier may be used for
authentication. A service responding to user authentication requests
(i.e - an "agent domain") MUST support one of the two types of
identifiers, and MAY support both. Client applications SHOULD
support both identifier types.
An "Account" is an administrative object holding one or more
references to an "Agent." This is advantageous in situations where:
1. The agent domain does not wish to use an agent first name and
last name to identify a user, but wishes to use another
identifier (such as an email address or account number,) or
2. The agent domain wishes to allow users with several agents to
authenticate with the same authenticator, freeing them from the
requirement of memorizing each individual agent authenticator.
3. It is the peer that is being authenticated, not an end user (this
occurs when domains must authenticate themselves to each other.)
Please note this spec does not imply a structure to the account
identifier. Though an agent domain may use an email address as an
account identifier, the protocol does not require it and treats the
identifier simply as an opaque sequence of octets.
This revision of the Open Grid Protocol defines, but does not require
the use of, three mechanisms for entity authentication: hashed
password, challenge-response and PKCS#5 Key Derivation 2.
Following successful authentication, the service will provide the
client with either a "maintenance capability" consumed in the
maintenance step documented below or a "seed capability" consumed in
the capability request / provisioning step (also described below.)
2.2. Maintenance
A service has the option of performing "per-client, authentication-
time maintenance" as part of the authentication sequence. Performing
maintenance after a client is authenticated and before a service
interface is used has several advantages:
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o it reduces system-wide downtime
o it distributes maintenance across time, and
o it consumes computational resources only for those clients who use
the system
The service signals it is performing maintenance by returning a
"Maintenance Capability" instead of a seed capability following
successful authentication. The maintenance capability represents a
finite sequence of transactions performed by the service on the
client's behalf. It is expected that maintenance is a task that will
complete in a "tractable" amount of time.
The maintenance capability may be queried to retrieve information
about the transactions that are occurring, including:
o a textual description of the maintenance being performed
o an estimate for how long the maintenance will take to complete
The service may provide a maintenance capability to the client
application in response to successful authentication. This
capability is communicated as a URI that identifies a resource with
the LLIDL interface described in the section below.
The client is expected to query the maintenance capability
periodically to receive status updates. Service implementers SHOULD
provide reasonable and accurate estimates of the time required to
complete maintenance. These estimates do not constitute a service
guarantee, merely a good-faith estimate of maintenance duration. One
of three responses will result in accessing a maintenance capability:
ongoing, next and complete. An "ongoing" response indicates the
server is still working on the same maintenance request, clients MAY
query the same capability at a later time. The "next" response
indicates the server is still performing maintenance, but is
performing a different task than described in the previous
capability. A complete "response" indicates that maintenance is
finished. This response type contains a seed capability used in the
next phase of service establishment.
2.3. Capability Request / Provisioning
Following authentication and the optional maintenance step of service
establishment, the client requests capabilities representing specific
resources from the server via the "seed capability" returned in the
authentication or maintenance steps described above. Seed
capabilities and capabilities in general are define in the OGP :
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Foundation [I-D.hamrick-llsd] document.
3. Authentication Mechanisms
3.1. User Authentication
Each Agent Domain MUST have a well known and published authentication
URL. The Second Life agent domain authentication URL is:
https://login.agni.secondlife.com/cgi-bin/auth.cgi
3.1.1. Preconditions
3.1.1.1. Client Preconditions
It is generally assumed that before a user attempts to log into an
agent domain, they will not be actively connected to that agent
domain.
It is also assumed that the user has registered their account and/or
agent; user registration is outside the scope of this specification.
The client application SHOULD present the agent domain's Terms of
Service and Critical Messages and allow a user to accept or decline
them prior to attempting to authenticate.
3.1.1.2. Agent Domain Preconditions
If the agent domain requires users to read and agree to the Terms of
Service or acknowledge receipt of Critical Messages prior to
authentication, it must maintain a record of which accounts and
agents have accepted and acknowledged these items.
Agent domains that support the concept of "suspension" or
"disablement" should also maintain a record of which accounts and
agents are suspended or disabled.
3.1.2. Postconditions
3.1.2.1. Client Postconditions
Following successful authentication, the client application SHOULD
note that the agent has been authenticated to the agent domain. The
Open Grid Protocol is NOT stateless.
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3.1.2.2. Agent Domain Postconditions
After an agent (or account) is authenticated, a seed capability is
allocated for the agent. The agent domain SHOULD maintain the
association between agent credentials (first_name and last_name) and
the seed capability so it may be re-used if the client attempts to
re-authenticate the user.
3.1.3. Side Effects
The agent domain SHOULD maintain the "presence" state of an agent.
This state should include the agent's seed capability. If a
previously authenticated and "present" agent re-authenticates
successfully, the agent domain MAY return the same seed capability.
After successful authentication, it is expected that the client will
issue another request against the seed capability. To defend against
potential Denial of Service attacks against the agent domain, the
agent domain MAY define a timeout period for the seed capability. If
the timeout period expires without a request being made against the
seed capability, that seed capability will expire. Successful
authentication of an agent who is "not present" has the effect of
starting this timer.
The Challenge-Response Authenticator is intended to be used with a
new, randomly generated salt for each authentication request. If the
agent domain supports the Challenge-Response authentication scheme,
it must maintain the "most recently generated salt" for some period
of time (generally until the expiration of the duration period given
in the authentication non-success response.)
After the salt has "timed out" following an unsuccessful Challenge-
Response authentication request, the agent domain MUST NOT allow the
use of a previous or fixed salt value. That is, it is not correct,
after the salt has expired, to use a null, fixed or previous salt.
The agent domain MUST generate a new salt and return it to the client
application. An unsuccessful authentication request with the
Challenge-Response scheme also has the side effect of starting the
salt duration timer. When this timer expires, the agent domain MUST
NOT allow authentication with previously generated salts.
3.1.4. Sequence of Events
It is possible for an authentication request to occur in conditions
where multiple errors or exceptions COULD be returned. As the
protocol does not support reporting multiple failure conditions, the
following sequence is provided to determine the priority of failure
conditions. This sequence of events is motivated by the following
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principles:
o The agent domain should leak no account status information to an
unauthenticated user.
o Maintenance should occur after successful authentication and
before account status checking in case maintenance involves the
representation of these states by the agent domain.
o The agent domain should check for "administrative issues" after
maintenance is complete.
The sequence for authentication is as follows. At the first error,
the system produces an appropriate error response.
1. If the authenticator provided is a Challenge-Response or PKCS#5
PBKDF2 type AND a secret is not included, the system returns an
authentication non-success response.
2. The secret and optional authentication parameters are used to
verify the client is in possession of the shared secret. If
authentication is unsuccessful, an authentication failure
response is returned.
3. If per-user login-time maintenance must be performed, the agent
domain allocates a maintenance capability and returns it to the
client application as a maintenance deferred success response.
4. If an account credential was used for authentication and the
account "contains" two or more agents and the client application
did not provide the first_name and last_name of the agent to log
in as, generate a list of all agents associated with this account
and return an agent selection failure response.
5. If an "administrative issue" exists such as the user is
suspended, banned, must agree to the terms of service or read
critical messages, the system returns a "user intervention
required" response, providing a URL referencing a web resource
explaining the administrative issue and describing remediation
steps.
6. Check to see if the authenticated agent is associated with an
agent seed capability already. If so, return a success response
referencing that seed capability.
7. Start the seed capability timer. Allocate an agent seed
capability and return it to the client application via a success
response.
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3.2. Peer Authentication using a TLS Client Certificate
In some cases, it may be advantageous to use an aspect of the
underlying transport to establish the client's identity. This
section describes a mechanism for interpreting identity information
inside a TLS client certificate [RFC5246] for the purpose of OGP
service establishment.
The use of TLS client certificates to authenticate the identity of
the client SHOULD be limited to situations other than user
authentication. It is included here as an option for establishing
inter-domain trust amongst server processes.
The inputs, outputs and side effects for peer authentication using a
TLS Client Certificate are the same as those for User Authentication
save the requirement that a user authenticator need not be provided.
Strictly speaking, a user identifier is also not required, but SHOULD
be included in cases where the subject name inside the leaf
certificate of the client certificate chain does not adequately
identify the client.
In practical terms this implies agent_login resources exposed for the
purpose of peer authentication MUST NOT require the client to include
the authenticator clause in the LLIDL description of the agent_login
resource defined below. Additionally, they MAY choose to ignore the
contents of the identifier clause defined below, using identity
information derived from the client certificate chain. Service
implementers are strongly cautioned that doing so may limit the
applicability of their service in environments where distinct
services with different trust characteristics are deployed on the
same host, using the same client certificate.
3.3. Peer Authentication using OAuth
The OAuth Protocol: Web Delegation [I-D.ietf-oauth-web-delegation]
draft describes a mechanism for deferring access control
authorization decisions to a third party. A service may expose an
interface capable of receiving a token defined in OAuth Protocol :
Authentication [I-D.ietf-oauth-authentication]. Clients accessing
such a service need not provide an identifier or a credential; it is
assumed that the owner of the resources being accessed has already
authorized access by the client (as evidenced by valid OAuth tokens.)
Conforming clients must still correctly consume responses from the
service including both maintenance and seed capabilities.
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4. Agent Login (Resource Class)
4.1. Inputs
LLIDL descriptions are provided below for both agent identifiers and
account identifiers. Client applications may use either as the basis
for authentication.
4.1.1. Agent Identifier
An agent identifier contains the first and last name of an agent.
4.1.2. Account Identifier
An account identifier must contain the account_name key. This is the
opaque sequence of octets used by the agent domain to identify the
user. If an account is associated with multiple agents, the client
application SHOULD include the first_name and last_name of the agent
the user wishes to use.
4.1.3. Hashed Password Authenticator
When a hashed password is used as an authenticator, the string '$1$'
is prepended to the UTF-8 encoding of the password and processed with
the MD5 cryptographic hash function. [RFC1321] This revision of the
Open Grid Protocol specification requires the use of MD5 with the
hashed password authenticator. It also requires the presence of the
algorithm key, and that the value of this key be the string 'md5'.
Note that future versions of this specification may ALLOW or REQUIRE
the use of other cryptographic hash functions.
4.1.4. Challenge-Response Authenticator
The Challenge-Response scheme allows the agent domain to select a
session specific "Salt" to be used in conjunction with the user's
password to generate an authenticator. In this scheme the
authenticator is the hash of the salt prepended to the hash of '$1$'
prepended to the password. This revision of the Open Grid Protocol
specification requires the use of SHA256 with the challenge-response
authenticator. [sha256] It also requires the presence of the
algorithm key, and that the value of this key be the string 'sha256'.
Note that future versions of this specification may ALLOW or REQUIRE
the use of other cryptographic hash functions.
To retrieve a session specific salt for use with the Challenge-
Response authentication scheme from the agent domain, the client
application sends a login request with a Challenge-Response
authenticator without the secret item. If the agent domain supports
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this authenticator, it MUST respond with a 'key' condition including
a salt and MAY include a duration in the response. If the duration
is present, it denotes the number of seconds for which the salt will
be valid.
The Challenge-Response Authentication Scheme is not currently
deployed on the Second Life Grid.
4.1.5. PKCS#5 PBKDF2 Authenticator
The PKCS#5 PBKDF2 authenticator is an implementation of RSA Labs'
Public Key Cryptographic Standards #5 v2.1 Password Based Key
Derivation Function #2. [pkcs5] In this scheme, the hash of the
string '$1$' prepended to the password is used in conjunction with a
salt, iteration count and hash function to generate an authenticator.
This revision of the Open Grid Protocol specification requires the
use of SHA256 with the PKCS#5 PBKDS2 authenticator. It also requires
the presence of the algorithm key, and that the value of this key be
the string 'sha256'. Note that future versions of this specification
may ALLOW or REQUIRE the use of other cryptographic hash functions.
As with the Challenge-Response authenticator, the agent domain MUST
include the salt and iteration count in its response to an
authentication request that is made without a secret item.
Conforming agent domains may include a duration in their response
indicating the number of seconds for which the salt and iteration
count will be valid.
The PKCS#5 PBKDF2 Authentication Scheme is not currently deployed
on the Second Life Grid.
4.2. Response
The response to the agent login message is notice of one of seven
"conditions":
o authentication success
o maintenance deferred success
o authentication non-success
o authentication failure
o agent selection failure
o "user intervention required" failure, and
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o "non-specific" failure.
The specification recognizes three "non-failure" responses:
4.2.1. Success
Upon success, the agent domain will respond with a message containing
the "Agent Seed Capability". Receipt of this capability indicates
authentication was successful. This capability is then used for
further interactions with the system.
4.2.2. Maintenance Deferred Success
This condition indicates per-agent (or per-account) login-time
maintenance is being performed. It is not an error. The response
includes a maintenance cap the client application should use to get
information about currently executing maintenance. For more
information about maintenance, see the Maintenance section below.
4.2.3. Authentication Non-Success
Authentication Non-Success is the response given when a client
queries the agent domain for agent-specific or account-specific
authentication parameters. In that it is the expected response to
such a query, it is not an error or exception. But it is not an
indication of successful authentication.
4.3. Errors and Exceptions
4.3.1. Authentication Failure
An authentication failure indicates the client application did not
provide enough information to authenticate the account or the agent.
4.3.2. Agent Selection Failure
An agent selection failure occurs when an account authentication
request is ambiguous. In other words, the account a user has
attempted to use to log in is associated with more than one agent
account and the client application did not specify which account to
use. The response includes a list of first_name / last_name pairs.
It is expected that the client application will present this list to
the user and ask which agent to use.
4.3.3. "User Intervention Required" Failure
This error indicates that the agent domain cannot authenticate the
user for non-technical reasons. The protocol does not attempt to
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describe why, or imply remediation for this error. But an agent
domain that returns this response MUST provide a URL containing a
message describing the condition leading to the error and
remediation, if known.
4.3.4. "Non Specific" Failure
This error indicates some other error exists which does not fall into
one of the previous six conditions.
4.4. Interface (POST)
The following text describes the LLIDL description of the agent_login
messages.
; authenticators
; hashed password authenticator
&authenticator = {
type: 'hash', ; identifies this as "hashed" type
algorithm: 'md5', ;
secret: binary ; hash of salt prepended to the password;
; s = h( '$1$' | pw )
}
; challenge response style authenticator
&authenticator = {
type: 'challenge', ; identifies this as a "challenge response"
algorithm: 'sha256', ;
salt: binary, ; optional - default is ( 0x24, 0x31, 0x24 )
secret: binary ; hash of the salt prepended to the password
; s = h( salt | h( '$1$' | pw ) )
}
; PKCS#5 PBKDF2 style authenticator
&authenticator = {
type: 'pkcs5pbkdf2', ; identifies authenticator as PKCS#5 PBKDF2
algorithm: string, ; identifier for hash ('md5' or 'sha256')
salt: binary, ; optional - default is ( 0x24, 0x31, 0x24 )
count: integer, ; optional - 1 used if not present
secret: binary ; hash of the salt prepended to the password
; s = pbkdf2( h('$1$' | pw),salt,count,128)
}
; identifier types
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; account identifier
&identifier = {
type: 'account', ; identifies this as an "account identifier"
account_name: string,
first_name: string, ; optional - first_name and last_name
last_name: string, ; identify agent to log in as for accounts
; with more than one agent
}
; agent identifier
&identifier = {
type: 'agent', ; identifies this as an "agent identifier"
first_name: string,
last_name: string,
}
; request
&credential = {
identifier: &identifier, ; account or agent identifier
authenticator: &authenticator ; 'hash', 'challenge'
; or 'pkcs5pbkdf2'
}
; response
; successful response
&response = {
condition: 'success',
agent_seed_capability: uri ; URL of the agent seed cap
}
; authentication failure
&response = {
condition: 'key',
salt: binary, ; optional - salt for challenge and PKCS5
count: integer, ; optional - iteration count for PKCS5
duration: integer ; optional - the duration of the validity
; period of salt and count values in
; seconds
}
; maintenance "non success"
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&response = {
condition: 'maintenance',
maintenance_capability: uri, ; URL of the maintenance cap
completion: integer ; an estimate for maintenance duration
; (in seconds)
}
; agent select failure
&response = {
condition: 'select',
agents: [ string, string, ... ]
}
; administrative failure
&response = {
condition: 'intervention',
message: uri ; a URI with human-readable text
; explaining what the user must do to
; continue
}
; non-specific error
&response = {
condition: 'nonspecific',
message: string ; a string describing the failure
; resource definition
%%agent_login
->&credential
<-&response
5. Login-Time Maintenance (Resource Class)
5.1. Inputs
There are no parameters to a maintenance capability request.
5.2. Response
There are three responses to a maintenance capability: a description
of ongoing maintenance, a new maintenance capability describing
another sequence of maintenance transactions, or a seed capability.
These responses are identified with the condition items: 'ongoing',
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'next' and 'complete'.
The 'ongoing' response to a maintenance capability request includes a
simple textual description of the maintenance performed, an estimate
for how long the maintenance is expected to take, and a validity
duration for the capability. The estimate for how long maintenance
will take is provided so client applications may provide feedback to
the user. The validity duration gives the viewer a minimum time
period the agent domain will maintain the maintenance capability.
When the agent domain returns a 'next' response, it indicates that
the current maintenance is complete, but a new maintenance must be
performed before the agent may be placed into a region. The 'next'
response includes the URL of the next maintenance capability as well
as an integer describing the minimum time period the agent domain
will maintain the maintenance capability.
When an agent domain returns a 'complete' response, it indicates that
all maintenance is complete. The response includes the agent seed
capability that may be used to place the user's avatar in a region.
It also includes an item describing the validity period for the
current maintenance capability.
5.3. Interface (GET)
The following text describes the LLIDL description of the agent_login
messages.
&response = {
condition: 'ongoing',
description: string,
duration: integer, ; seconds before maintenance is complete
}
&response = {
condition: 'next',
description: string,
maintenance_capability: uri ; URL for the next maintenance capability
}
&response = {
condition: 'complete',
agent_seed_capability: uri ; the agent's seed cap
}
%%maintenance
->undef
<-&response
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6. Security Considerations
RFC 3552 [RFC3552] describes several aspects to use when evaluating
the security of a specification or implementation. We believe most
common security concerns users of this specification will encounter
are more appropriately considered as transport, network or link layer
issues. However, the following "application security" issues should
be considered.
The MD5 cryptographic hash functions has been deprecated and SHOULD
be used only for compatibility with older applications.
The use of the hashed password authenticator could result in a replay
attack if not used in conjunction with an appropriate confidentiality
preserving transport. Implementations using the hashed password
authenticator SHOULD utilize appropriate encryption schemes such as
TLS [RFC5246] or S/MIME [RFC3851].
7. IANA Considerations
This document has no actions for IANA.
8. References
8.1. Normative References
[I-D.hamrick-llsd]
Brashears, A., Hamrick, M., and M. Lentczner, "Linden Lab
Structured Data", 2008.
[I-D.ietf-oauth-authentication]
Hammer-Lahav, E., "The OAuth Protocol: Authentication",
draft-ietf-oauth-authentication-01 (work in progress),
July 2009.
[I-D.ietf-oauth-web-delegation]
Hammer-Lahav, E., "The OAuth Protocol: Web Delegation",
draft-ietf-oauth-web-delegation-01 (work in progress),
July 2009.
[I-D.lentczner-ogp-base]
Lentczner, M., "Open Grid Protocol: Foundation",
draft-lentczner-ogp-base-00 (work in progress),
March 2009.
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
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April 1992.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[pkcs5] Kaliski, B., "PKCS #5: Password-Based Cryptography
Specification Version 2.0".
[sha256] ""Federal Information Processing Standards Publication
180-2 (+ Change Notice to include SHA-224)".
8.2. Informative References
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552,
July 2003.
[RFC3851] Ramsdell, B., "Secure/Multipurpose Internet Mail
Extensions (S/MIME) Version 3.1 Message Specification",
RFC 3851, July 2004.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
Appendix A. Acknowledgements
The author gratefully acknowledges the contributions of David Levine
and John Hurliman whose participation made this document apropos to a
wider range of use cases than would have originally been the case.
Authors' Addresses
Tess Chu
Linden Research, Inc.
945 Battery St.
San Francisco, CA 94111
US
Phone: +1 415 243 9000
Email: tess@lindenlab.com
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Meadhbh Siobhan Hamrick
Linden Research, Inc.
945 Battery St.
San Francisco, CA 94111
US
Phone: +1 650 283 0344
Email: infinity@lindenlab.com
Mark Lentczner
Linden Research, Inc.
945 Battery St.
San Francisco, CA 94111
US
Phone: +1 415 243 9000
Email: zero@lindenlab.com
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