draft-ietf-asid-ldapv3-tls-01.txt   draft-ietf-asid-ldapv3-tls-02.txt 
ASID Working Group Jeff Hodges, Stanford ASID Working Group Jeff Hodges, Stanford
INTERNET-DRAFT RL "Bob" Morgan, Stanford INTERNET-DRAFT RL "Bob" Morgan, Stanford
Mark Wahl, Critical Angle Inc. Category: Standards Track Mark Wahl, Critical Angle Inc.
June, 1997 August, 1997
Lightweight Directory Access Protocol (v3): Lightweight Directory Access Protocol (v3):
Extension for Transport Layer Security Extension for Transport Layer Security
draft-ietf-asid-ldapv3-tls-01.txt draft-ietf-asid-ldapv3-tls-02.txt
1. Status of this Memo Status of this Document
This document is an Internet-Draft. Internet-Drafts are working docu- This document is an Internet-Draft. Internet-Drafts are working docu-
ments of the Internet Engineering Task Force (IETF), its areas, and its ments of the Internet Engineering Task Force (IETF), its areas, and its
working groups. Note that other groups may also distribute working working groups. Note that other groups may also distribute working doc-
documents as Internet-Drafts. uments as Internet-Drafts.
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 material time. It is inappropriate to use Internet- Drafts as reference material
or to cite them other than as ``work in progress.'' or to cite them other than as ``work in progress.''
To learn the current status of any Internet-Draft, please check the To learn the current status of any Internet-Draft, please check the
``1id-abstracts.txt'' listing contained in the Internet- Drafts Shadow ``1id-abstracts.txt'' listing contained in the Internet- Drafts Shadow
Directories on ds.internic.net (US East Coast), nic.nordu.net (Europe), Directories on ds.internic.net (US East Coast), nic.nordu.net (Europe),
ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim). ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim).
2. Abstract This document expires in February 1998.
1. Abstract
This document defines the "Start Transport Layer Security (TLS) Opera- This document defines the "Start Transport Layer Security (TLS) Opera-
tion" for LDAP [LDAPv3, TLS]. This operation provides for TLS establish- tion" for LDAP [LDAPv3, TLS]. This operation provides for TLS establish-
ment in an LDAP association and is defined in terms of an LDAP extended ment in an LDAP association and is defined in terms of an LDAP extended
request. request.
2. Conventions Used in this Document
The key words "MUST", "SHOULD", and "MAY" used in this document are to The key words "MUST", "SHOULD", and "MAY" used in this document are to
be interpreted as described in [Bradner97]. be interpreted as described in [ReqsKeywords].
3. The Start TLS Operation 3. The Start TLS Operation
3.1. Requesting TLS Establishment 3.1. Requesting TLS Establishment
A client may perform a Start TLS operation by transmitting an LDAP PDU A client may perform a Start TLS operation by transmitting an LDAP PDU
I-D LDAPv3: Extension for Transport Layer Security August 1997
containing an ExtendedRequest [LDAPv3] specifying the OID for the Start containing an ExtendedRequest [LDAPv3] specifying the OID for the Start
TLS operation: TLS operation:
1.3.6.1.4.1.1466.20037 1.3.6.1.4.1.1466.20037
An LDAP ExtendedRequest is defined as follows: An LDAP ExtendedRequest is defined as follows:
ExtendedRequest ::= [APPLICATION 23] SEQUENCE { ExtendedRequest ::= [APPLICATION 23] SEQUENCE {
requestName [0] LDAPOID, requestName [0] LDAPOID,
requestValue [1] OCTET STRING OPTIONAL } requestValue [1] OCTET STRING OPTIONAL }
A Start TLS extended request is formed by setting the requestName field A Start TLS extended request is formed by setting the requestName field
to the OID string given above. The requestValue field is absent. The to the OID string given above. The requestValue field is absent. The
client MUST NOT send any PDUs on this connection following this request client MUST NOT send any PDUs on this connection following this request
until it receives a Start TLS extended response. until it receives a Start TLS extended response.
When a Start TLS extended request is made, the server MUST return an When a Start TLS extended request is made, the server MUST return an
LDAP PDU containing a Start TLS extended response. An LDAP Exten- LDAP PDU containing a Start TLS extended response. An LDAP Extende-
dedResponse is defined as follows: dResponse is defined as follows:
ExtendedResponse ::= [APPLICATION 24] SEQUENCE { ExtendedResponse ::= [APPLICATION 24] SEQUENCE {
responseName [0] LDAPOID OPTIONAL, responseName [0] LDAPOID OPTIONAL,
response [1] OCTET STRING OPTIONAL, response [1] OCTET STRING OPTIONAL,
standardResponse [2] LDAPResult } standardResponse [2] LDAPResult }
A Start TLS extended response MUST contain a responseName field which A Start TLS extended response MUST contain a responseName field which
MUST be set to the same string as that present in the Start TLS extended MUST be set to the same string as that present in the Start TLS extended
request. The response field is absent. The server MUST set the request. The response field is absent. The server MUST set the result-
resultCode of the standardResponse field to either success or one of the Code of the standardResponse field to either success or one of the other
other values outlined in section 3.3. values outlined in section 3.3.
3.2. "Success" Response 3.2. "Success" Response
If the standardResponse field contains a resultCode of success, this If the standardResponse field contains a resultCode of success, this
indicates that the server is willing and able to negotiate TLS. At this indicates that the server is willing and able to negotiate TLS. At this
point the client, which has ceased to transfer LDAP requests on the con- point the client, which has ceased to transfer LDAP requests on the con-
nection, MUST either begin a TLS negotiation, or close the connection. nection, MUST either begin a TLS negotiation, or close the connection.
In the former case, the client will send PDUs in the TLS Record Protocol In the former case, the client will send PDUs in the TLS Record Protocol
directly over the underlying TCP bytestream to the server. directly over the underlying TCP bytestream to the server.
After the TLS connection is established, both parties MUST individually After the TLS connection is established, both parties MUST individually
decide whether or not to continue based on the privacy level achieved. decide whether or not to continue based on the privacy level achieved.
Ascertaining the TLS connection's privacy level is implementation depen- Ascertaining the TLS connection's privacy level is implementation depen-
dent, and accomplished by communicating with one's respective local TLS dent, and accomplished by communicating with one's respective local TLS
implementation. implementation.
If the client or server decides that the level of authentication or If the client or server decides that the level of authentication or pri-
privacy is not high enough for it to continue, it SHOULD close the TLS vacy is not high enough for it to continue, it SHOULD close the TLS
connection immediately after the TLS negotiation has completed, to
disconnect the TLS service and return to an LDAP state (see section 5, I-D LDAPv3: Extension for Transport Layer Security August 1997
below). This will cause the client's authorization identity to be reset
to anonymous. The client MAY attempt to Start TLS again, or MAY send an connection immediately after the TLS negotiation has completed, to dis-
unbind request, or send any other LDAP request. connect the TLS service and return to an LDAP state (see section 5,
below). This will cause the client's authorization identity to be
reset to anonymous. The client MAY attempt to Start TLS again, or MAY
send an unbind request, or send any other LDAP request.
3.3. Response other than "success" 3.3. Response other than "success"
If the standardResponse field contains a resultCode other than success, If the standardResponse field contains a resultCode other than success,
this indicates that the server is unwilling or unable to negotiate TLS. this indicates that the server is unwilling or unable to negotiate TLS.
If the Start TLS extended request was not successful, the resultCode If the Start TLS extended request was not successful, the resultCode
will be one of: will be one of:
- operationsError (operations sequencing incorrect; e.g. TLS already - operationsError (operations sequencing incorrect; e.g. TLS already
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the connection. the connection.
4. Sequencing of the Start TLS Operation 4. Sequencing of the Start TLS Operation
The client MAY send the Start TLS extended request at any time after The client MAY send the Start TLS extended request at any time after
establishing an LDAP association, except that in the following cases the establishing an LDAP association, except that in the following cases the
client MUST NOT send a Start TLS extended request: client MUST NOT send a Start TLS extended request:
- if TLS is currently established on the connection, or - if TLS is currently established on the connection, or
- during a multi-stage SASL negotiation, or - during a multi-stage SASL negotiation, or
I-D LDAPv3: Extension for Transport Layer Security August 1997
- if there are any LDAP operations outstanding on the connection. - if there are any LDAP operations outstanding on the connection.
The result of violating any of these requirements is described above in The result of violating any of these requirements is described above in
section 3.3. section 3.3.
The client MAY have already perfomed a Bind operation when it sends a The client MAY have already perfomed a Bind operation when it sends a
Start TLS request, or the client might have not yet bound. Start TLS request, or the client might have not yet bound.
If the client did not establish a TLS connection before sending any If the client did not establish a TLS connection before sending any
other requests, and the server requires the client to establish a TLS other requests, and the server requires the client to establish a TLS
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Before closing a TLS connection, the client MUST either wait for any Before closing a TLS connection, the client MUST either wait for any
outstanding LDAP operations to complete, or explicitly abandon them outstanding LDAP operations to complete, or explicitly abandon them
[LDAPv3]. [LDAPv3].
After the initiator of a close has sent a closure alert, it MUST discard After the initiator of a close has sent a closure alert, it MUST discard
any TLS messages until it has received an alert from the other party. any TLS messages until it has received an alert from the other party.
It will cease to send TLS Record Protocol PDUs, and following the It will cease to send TLS Record Protocol PDUs, and following the
reciept of the alert, MAY send and receive LDAP PDUs. reciept of the alert, MAY send and receive LDAP PDUs.
The other party, if it receives a closure alert, MUST immediately The other party, if it receives a closure alert, MUST immediately trans-
transmit a TLS closure alert. It will subequently cease to send TLS mit a TLS closure alert. It will subequently cease to send TLS Record
Record Protocol PDUs, and MAY send and receive LDAP PDUs. Protocol PDUs, and MAY send and receive LDAP PDUs.
5.2. Abrupt Closure 5.2. Abrupt Closure
Either the client or server MAY abruptly close the entire LDAP associa- Either the client or server MAY abruptly close the entire LDAP associa-
tion and any TLS connection established on it by dropping the underlying tion and any TLS connection established on it by dropping the underlying
TCP connection. A server MAY beforehand send the client a Notice of TCP connection. A server MAY beforehand send the client a Notice of Dis-
Disconnection [LDAPv3] in this case. connection [LDAPv3] in this case.
6. Effects of TLS Establishment on the Client's Authorization Identity 6. Effects of TLS on the Client's Authorization Identity
This section first defines terms, and then describes the effects of TLS
establishment and closure on the client's authorization identity in
terms of those definitions.
I-D LDAPv3: Extension for Transport Layer Security August 1997
6.1. Authorization-Related Definitions
6.1.1. Security policy
A security policy is a set of rules defining the protection of
resources, generally in terms of the capabilities of persons or other
agents accessing those resources. A common example of a security policy
is an access control list. Security mechanisms such as those described
here work in support of the enforcement of security policies.
6.1.2. Authentication, Credentials, Identity
An authentication credential is the evidence supplied by one party to
another, asserting the identity of the supplying party (typically a
user) who is attempting to establish an association with the other party
(typically a server). Authentication is the process of generating,
transmitting, and verifying these credentials. An authentication iden-
tity is the name presented in a credential.
There are many forms of authentication credentials -- the form used
depends upon the particular authentication mechanism negotiated by the
parties. For example: X.509 certificates, Kerberos tickets, simple
identity and password pairs. Note that an authentication mechanism may
constrain the form of authentication identities used with it.
6.1.3. Authorization Identity
An authorization identity is a name used in expressions of security
policies, in particular the name of a user or other agent that may
access a resource or request that an operation be performed. Typically
a server, when processing a request, will use its security policies and
the authorization identity associated with the request to determine
whether and how to process the request.
The authorization identity bound to an association is often exactly the
same as the authentication identity presented by the client, but it MAY
be different. SASL allows clients to specify an authorization identity
distinct from the authentication identity supplied by the client's cre-
dentials. This permits agents such as proxy servers to authenticate
using their own credentials, yet request the access privileges of the
identity for which they are proxying [SASL]. Also, the form of authen-
tication identity supplied by a service like TLS may not correspond to
the authorization identities used to express a server's security policy,
requiring a server-specific mapping to be done. The method by which a
server composes and validates an authorization identity from the creden-
tials and identities supplied by a client is implementation-specific.
I-D LDAPv3: Extension for Transport Layer Security August 1997
6.2. Session Establishment Effects
Upon establishment of the TLS connection onto the LDAP association, the Upon establishment of the TLS connection onto the LDAP association, the
server MAY base the client's authorization identity on the client's server MAY base the client's authorization identity on the client's
negotiated TLS credentials, overriding any previously established negotiated TLS credentials, overriding any previously established cre-
credentials and authorization identity. Otherwise, any previously esta- dentials and authorization identity. Otherwise, any previously estab-
blished credentials and authorization identity MUST remain in force, lished credentials and authorization identity MUST remain in force,
including anonymous cedentials and identity in the case where the client including anonymous credentials and identity in the case where the
had not previously bound. client had not previously bound.
A client MAY explicitly request that its authenticated TLS credentials A client MAY explicitly request that its authenticated TLS credentials
be used as the source for its LDAP authorization identity. This is be used as a source for its LDAP authorization identity. This is accom-
accomplished after TLS establishment by invoking a Bind request of the plished after TLS establishment by invoking a Bind request of the SASL
SASL form with a negotiated mechanism name of "EXTERNAL" [SASL]. The form with a negotiated mechanism name of "EXTERNAL" [SASL].
credentials field MAY contain the client's distinguished name (as an
LDAP string), or it MAY be empty. If it does contain a distinguished The credentials field (in the SaslCredentials field in the Bind Request)
name, this name MUST match the authorization identity negotiated by TLS MAY contain an authorization identity, or it MAY be empty. If it does
as the client's identity. It is a matter of local policy what consti- contain an identity, the server uses its security policy to determine
tutes a match. In the absence of local policy, the default matching pol- whether the client is authorized to authenticate as that identity. The
icy compares for equality. The server MUST reject the Bind operation server MUST reject the Bind operation with an invalidAuthorizationId
with an invalidCredentials resultCode in the Bind response if they do resultCode in the Bind response if the client is not so authorized.
not match.
6.3. Session Closure Effects
Closure of the TLS connection MUST cause the LDAP association to move to Closure of the TLS connection MUST cause the LDAP association to move to
an anonymous authentication and authorization state regardless of the an anonymous authentication and authorization state regardless of the
state established over TLS and regardless of the authentication and state established over TLS and regardless of the authentication and
authorization state prior to TLS connection establishment. authorization state prior to TLS connection establishment.
7. Security Considerations 7. Security Considerations
The goals of using the TLS protocol with LDAP are to ensure connection The goals of using the TLS protocol with LDAP are to ensure connection
confidentiality and integrity, and to optionally provide for authentica- confidentiality and integrity, and to optionally provide for authentica-
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The use of TLS does not provide or ensure for confidentiality and/or The use of TLS does not provide or ensure for confidentiality and/or
non-repudiation of the data housed by an LDAP-based directory server. non-repudiation of the data housed by an LDAP-based directory server.
Once established, TLS only provides for and ensures confidentiality and Once established, TLS only provides for and ensures confidentiality and
integrity of the operations and data in transit over the LDAP associa- integrity of the operations and data in transit over the LDAP associa-
tion, and only if the implementations on the client and server support tion, and only if the implementations on the client and server support
and negotiate it. and negotiate it.
The level of security provided though the use of TLS depends directly on The level of security provided though the use of TLS depends directly on
both the quality of the TLS implementation used and the style of usage both the quality of the TLS implementation used and the style of usage
I-D LDAPv3: Extension for Transport Layer Security August 1997
of that implementation. Both parties SHOULD independently ascertain and of that implementation. Both parties SHOULD independently ascertain and
consent to the privacy level achieved once TLS is established and before consent to the privacy level achieved once TLS is established and before
begining use of the TLS connection. For example, the privacy level of begining use of the TLS connection. For example, the privacy level of
the TLS connection might have been negotiated down to plaintext. the TLS connection might have been negotiated down to plaintext.
Client and server implementors SHOULD take measures to ensure proper Client and server implementors SHOULD take measures to ensure proper
protection of credentials and other confidential data where such meas- protection of credentials and other confidential data where such mea-
ures are not otherwise provided by the TLS implementation. sures are not otherwise provided by the TLS implementation.
Server implementors SHOULD allow for server administrators to elect Server implementors SHOULD allow for server administrators to elect
whether and when connection confidentiality is required. whether and when connection confidentiality is required.
8. Acknowledgements 8. Acknowledgements
The authors thank Tim Howes and Paul Hoffman for their contributions to The authors thank Tim Howes, Paul Hoffman, and John Kristian for their
this document. contributions to this document.
9. References 9. References
[Bradner97]
Scott Bradner, "Key Words for use in RFCs to Indicate Requirement
Levels", Internet Draft, RFC 2119.
[LDAPv3] [LDAPv3]
M. Wahl, S. Kille and T. Howes, "Lightweight Directory Access Pro- M. Wahl, S. Kille and T. Howes, "Lightweight Directory Access Pro-
tocol (v3)", Internet Draft, February, 1997. Available as draft- tocol (v3)", Internet Draft (work in progress), February, 1997.
ietf-asid-ldapv3-protocol-04.txt. Available as draft-ietf-asid-ldapv3-protocol-06.txt.
[TLS]Tim Dierks, C. Allen, "The TLS Protocol Version 1.0", Internet [ReqsKeywords]
Draft, March 1997. Available as draft-ietf-tls-protocol-03.txt Scott Bradner, "Key Words for use in RFCs to Indicate Requirement
Levels", RFC 2119.
[SASL]J. Myers, "Simple Authentication and Security Layer (SASL)", [SASL]J. Myers, "Simple Authentication and Security Layer (SASL)",
Internet Draft, April 1997. Available as draft-myers-auth-sasl- Internet Draft (work in progress), April 1997. Available as draft-
10.txt myers-auth-sasl-11.txt
[TLS]Tim Dierks, C. Allen, "The TLS Protocol Version 1.0", Internet
Draft (work in progress), March 1997. Available as draft-ietf-tls-
protocol-03.txt
10. Author's Address 10. Author's Address
Jeff Hodges Jeff Hodges
Computing & Communication Services Computing & Communication Services
Stanford University Stanford University
115 Pine Hall Pine Hall
241 Panama Street
Stanford, CA 94305-4122 Stanford, CA 94305-4122
USA USA
Phone: +1-415-723-2452 Phone: +1-415-723-2452
EMail: Jeff.Hodges@Stanford.edu EMail: Jeff.Hodges@Stanford.edu
I-D LDAPv3: Extension for Transport Layer Security August 1997
RL "Bob" Morgan RL "Bob" Morgan
Computing & Communication Services Computing & Communication Services
Stanford University Stanford University
115 Pine Hall Pine Hall
241 Panama Street
Stanford, CA 94305-4122 Stanford, CA 94305-4122
USA USA
Phone: +1-415-723-9711 Phone: +1-415-723-9711
EMail: Bob.Morgan@Stanford.edu EMail: Bob.Morgan@Stanford.edu
Mark Wahl Mark Wahl
Critical Angle Inc. Critical Angle Inc.
4815 W. Braker Lane #502-385 4815 W. Braker Lane #502-385
Austin, TX 78759 Austin, TX 78759
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