oysteikt/heimdal
0
0
Fork 0
Code Issues 5 Pull Requests Releases Activity

x

Browse Source 
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@20038 ec53bebd-3082-4978-b11e-865c3cabbd6b
This commit is contained in:
Love Hörnquist Åstrand
2007-01-23 17:23:50 +00:00
parent cbb9bd8b2b
commit a595414294
2 changed files with 734 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

451
doc/standardisation/rfc4401.txt Normal file
View File

@@ -0,0 +1,451 @@
Network Working Group N. Williams
Request for Comments: 4401 Sun Microsystems
Category: Standards Track February 2006
A Pseudo-Random Function (PRF) API Extension for the
Generic Security Service Application Program Interface (GSS-API)
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document defines a Pseudo-Random Function (PRF) extension to the
Generic Security Service Application Program Interface (GSS-API) for
keying application protocols given an established GSS-API security
context. The primary intended use of this function is to key secure
session layers that do not or cannot use GSS-API per-message message
integrity check (MIC) and wrap tokens for session protection.
Table of Contents
1. Introduction ....................................................2
1.1. Conventions Used in This Document ..........................2
2. GSS_Pseudo_random() .............................................2
2.1. C-Bindings .................................................5
3. IANA Considerations .............................................5
4. Security Considerations .........................................5
5. References ......................................................7
5.1. Normative References .......................................7
5.2. Informative References .....................................7
Williams Standards Track [Page 1]
RFC 4401 A PRF Extension for the GSS-API February 2006
1. Introduction
A need has arisen for users of the GSS-API to key applications'
cryptographic protocols using established GSS-API security contexts.
Such applications can use the GSS-API [RFC2743] for authentication,
but not for transport security (for whatever reasons), and since the
GSS-API does not provide a method for obtaining keying material from
established security contexts, such applications cannot make
effective use of the GSS-API.
To address this need, we define a pseudo-random function (PRF)
extension to the GSS-API.
Though this document specifies an abstract API as an extension to the
GSS-API version 2, update 1, and though it specifies the bindings of
this extension for the C programming language, it does not specify a
revision of the GSS-API and so does not address the matter of how
portable applications detect support for and ensure access to this
extension. We defer this matter to an expected, comprehensive update
to the GSS-API.
1.1. Conventions Used in This Document
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 [RFC2119].
2. GSS_Pseudo_random()
Inputs:
o context CONTEXT handle,
o prf_key INTEGER,
o prf_in OCTET STRING,
o desired_output_len INTEGER
Outputs:
o major_status INTEGER,
o minor_status INTEGER,
o prf_out OCTET STRING
Williams Standards Track [Page 2]
RFC 4401 A PRF Extension for the GSS-API February 2006
Return major_status codes:
o GSS_S_COMPLETE indicates no error.
o GSS_S_NO_CONTEXT indicates that a null context has been provided
as input.
o GSS_S_CONTEXT_EXPIRED indicates that an expired context has been
provided as input.
o GSS_S_UNAVAILABLE indicates that the mechanism lacks support for
this function or, if the security context is not fully
established, that the context is not ready to compute the PRF with
the given prf_key, or that the given prf_key is not available.
o GSS_S_FAILURE indicates general failure, possibly due to the given
input data being too large or of zero length, or due to the
desired_output_len being zero; the minor status code may provide
additional information.
This function applies the established context's mechanism's keyed
pseudo-random function (PRF) to the input data ('prf_in'), keyed with
key material associated with the given security context and
identified by 'prf_key', and outputs the resulting octet string
('prf_out') of desired_output_len length.
The minimum input data length is one octet.
Mechanisms MUST be able to consume all the provided prf_in input data
that is 2^14 or fewer octets.
If a mechanism cannot consume as much input data as provided by the
caller, then GSS_Pseudo_random() MUST return GSS_S_FAILURE.
The minimum desired_output_len is one.
Mechanisms MUST be able to output at least up to 2^14 octets.
If the implementation cannot produce the desired output due to lack
of resources, then it MUST return GSS_S_FAILURE and MUST set a
suitable minor status code.
The prf_key can take on the following values: GSS_C_PRF_KEY_FULL,
GSS_C_PRF_KEY_PARTIAL, or mechanism-specific values, if any. This
parameter is intended to distinguish between the best cryptographic
keys that may be available only after full security context
establishment and keys that may be available prior to full security
context establishment. For some mechanisms, or contexts, those two
Williams Standards Track [Page 3]
RFC 4401 A PRF Extension for the GSS-API February 2006
prf_key values MAY refer to the same cryptographic keys; for
mechanisms like the Kerberos V GSS-API mechanism [RFC1964] where one
peer may assert a key that may be considered better than the others
they MAY be different keys.
GSS_C_PRF_KEY_PARTIAL corresponds to a key that would have been used
while the security context was partially established, even if it is
fully established when GSS_Pseudo_random() is actually called.
Mechanism-specific prf_key values are intended to refer to any other
keys that may be available.
The GSS_C_PRF_KEY_FULL value corresponds to the best key available
for fully-established security contexts.
GSS_Pseudo_random() has the following properties:
o its output string MUST be a pseudo-random function [GGM1] [GGM2]
of the input keyed with key material from the given security
context -- the chances of getting the same output given different
input parameters should be exponentially small.
o when successfully applied to the same inputs by an initiator and
acceptor using the same security context, it MUST produce the
_same results_ for both, the initiator and acceptor, even if
called multiple times (as long as the security context is not
expired).
o upon full establishment of a security context, all cryptographic
keys and/or negotiations used for computing the PRF with any
prf_key MUST be authenticated (mutually, if mutual authentication
is in effect for the given security context).
o the outputs of the mechanism's GSS_Pseudo_random() (for different
inputs) and its per-message tokens for the given security context
MUST be "cryptographically separate"; in other words, it must not
be feasible to recover key material for one mechanism operation or
transform its tokens and PRF outputs from one to the other given
only said tokens and PRF outputs. (This is a fancy way of saying
that key derivation and strong cryptographic operations and
constructions must be used.)
o as implied by the above requirement, it MUST NOT be possible to
access any raw keys of a security context through
GSS_Pseudo_random(), no matter what inputs are given.
Williams Standards Track [Page 4]
RFC 4401 A PRF Extension for the GSS-API February 2006
2.1. C-Bindings
#define GSS_C_PRF_KEY_FULL 0
#define GSS_C_PRF_KEY_PARTIAL 1
OM_uint32 gss_pseudo_random(
OM_uint32 *minor_status,
gss_ctx_id_t context,
int prf_key,
const gss_buffer_t prf_in,
ssize_t desired_output_len,
gss_buffer_t prf_out
);
Additional major status codes for the C-bindings:
o GSS_S_CALL_INACCESSIBLE_READ
o GSS_S_CALL_INACCESSIBLE_WRITE
See [RFC2744].
3. IANA Considerations
This document has no IANA considerations currently. If and when a
relevant IANA registry of GSS-API symbols is created, then the
generic and language-specific function names, constant names, and
constant values described above should be added to such a registry.
4. Security Considerations
Care should be taken in properly designing a mechanism's PRF
function.
GSS mechanisms' PRF functions should use a key derived from contexts'
authenticated session keys and should preserve the forward security
properties of the mechanisms' key exchanges.
Some mechanisms may support the GSS PRF function with security
contexts that are not fully established, but applications MUST assume
that authentication, mutual or otherwise, has not completed until the
security context is fully established.
Callers of GSS_Pseudo_random() should avoid accidentally calling it
with the same inputs. One useful technique is to prepend to the
prf_in input string, by convention, a string indicating the intended
purpose of the PRF output in such a way that unique contexts in which
the function is called yield unique inputs to it.
Williams Standards Track [Page 5]
RFC 4401 A PRF Extension for the GSS-API February 2006
Pseudo-random functions are, by their nature, capable of producing
only limited amounts of cryptographically secure output. The exact
amount of output that one can safely use, unfortunately, varies from
one PRF to another (which prevents us from recommending specific
numbers). Because of this, we recommend that unless you really know
what you are doing (i.e., you are a cryptographer and are qualified
to pass judgement on cryptographic functions in areas of period,
presence of short cycles, etc.), you limit the amount of the PRF
output used to the necessary minimum. See [RFC4086] for more
information about "Randomness Requirements for Security".
For some mechanisms, the computational cost of computing
GSS_Pseudo_random() may increase significantly as the length of the
prf_in data and/or the desired_output_length increase. This means
that if an application can be tricked into providing very large input
octet strings and requesting very long output octet strings, then
that may constitute a denial of service attack on the application;
therefore, applications SHOULD place appropriate limits on the size
of any input octet strings received from their peers without
integrity protection.
Williams Standards Track [Page 6]
RFC 4401 A PRF Extension for the GSS-API February 2006
5. References
5.1. Normative References
[GGM1] Goldreich, O., Goldwasser, S., and S. Micali, "How to
Construct Random Functions", Journal of the ACM, October
1986.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2743] Linn, J., "Generic Security Service Application Program
Interface Version 2, Update 1", RFC 2743, January 2000.
[RFC2744] Wray, J., "Generic Security Service API Version 2 :
C-bindings", RFC 2744, January 2000.
5.2. Informative References
[GGM2] Goldreich, O., Goldwasser, S., and S. Micali, "On the
Cryptographic Applications of Random Functions",
Proceedings of CRYPTO 84 on Advances in cryptology, 1985.
[RFC4086] Eastlake, D., 3rd, Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086,
June 2005.
[RFC1964] Linn, J., "The Kerberos Version 5 GSS-API Mechanism", RFC
1964, June 1996.
Author's Address
Nicolas Williams
Sun Microsystems
5300 Riata Trace Ct
Austin, TX 78727
US
EMail: Nicolas.Williams@sun.com
Williams Standards Track [Page 7]
RFC 4401 A PRF Extension for the GSS-API February 2006
Full Copyright Statement
Copyright (C) The Internet Society (2006).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Acknowledgement
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
Williams Standards Track [Page 8]

283
doc/standardisation/rfc4402.txt Normal file
View File

@@ -0,0 +1,283 @@
Network Working Group N. Williams
Request for Comments: 4402 Sun
Category: Standards Track February 2006
A Pseudo-Random Function (PRF) for the Kerberos V Generic Security
Service Application Program Interface (GSS-API) Mechanism
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document defines the Pseudo-Random Function (PRF) for the
Kerberos V mechanism for the Generic Security Service Application
Program Interface (GSS-API), based on the PRF defined for the
Kerberos V cryptographic framework, for keying application protocols
given an established Kerberos V GSS-API security context.
Table of Contents
1. Introduction ....................................................2
1.1. Conventions Used in This Document ..........................2
2. Kerberos V GSS Mechanism PRF ....................................2
3. IANA Considerations .............................................3
4. Security Considerations .........................................3
5. Normative References ............................................4
Williams Standards Track [Page 1]
RFC 4402 A PRF for the Kerberos V Mechanism February 2006
1. Introduction
This document specifies the Kerberos V GSS-API mechanism's [RFC4121]
pseudo-random function corresponding to [RFC4401]. The function is a
"PRF+" style construction. For more information see [RFC4401],
[RFC2743], [RFC2744], and [RFC4121].
1.1. Conventions Used in This Document
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 [RFC2119].
2. Kerberos V GSS Mechanism PRF
The GSS-API PRF [RFC4401] function for the Kerberos V mechanism
[RFC4121] shall be the output of a PRF+ function based on the
encryption type's PRF function keyed with the negotiated session key
of the security context corresponding to the 'prf_key' input
parameter of GSS_Pseudo_random().
This PRF+ MUST be keyed with the key indicated by the 'prf_key' input
parameter as follows:
o GSS_C_PRF_KEY_FULL -- use the sub-session key asserted by the
acceptor, if any, or the sub-session asserted by the initiator, if
any, or the Ticket's session key
o GSS_C_PRF_KEY_PARTIAL -- use the sub-session key asserted by the
initiator, if any, or the Ticket's session key
The PRF+ function is a simple counter-based extension of the Kerberos
V pseudo-random function [RFC3961] for the encryption type of the
security context's keys:
PRF+(K, L, S) = truncate(L, T1 || T2 || .. || Tn)
Tn = pseudo-random(K, n || S)
where '||' is the concatenation operator, 'n' is encoded as a network
byte order 32-bit unsigned binary number, truncate(L, S) truncates
the input octet string S to length L, and pseudo-random() is the
Kerberos V pseudo-random function [RFC3961].
The maximum output size of the Kerberos V mechanism's GSS-API PRF
then is, necessarily, 2^32 times the output size of the pseudo-
random() function for the encryption type of the given key.
Williams Standards Track [Page 2]
RFC 4402 A PRF for the Kerberos V Mechanism February 2006
When the input size is longer than 2^14 octets as per [RFC4401] and
exceeds an implementation's resources, then the mechanism MUST return
GSS_S_FAILURE and GSS_KRB5_S_KG_INPUT_TOO_LONG as the minor status
code.
3. IANA Considerations
This document has no IANA considerations currently. If and when a
relevant IANA registry of GSS-API symbols and constants is created,
then the GSS_KRB5_S_KG_INPUT_TOO_LONG minor status code should be
added to such a registry.
4. Security Considerations
Kerberos V encryption types' PRF functions use a key derived from
contexts' session keys and should preserve the forward security
properties of the mechanisms' key exchanges.
Legacy Kerberos V encryption types may be weak, particularly the
single-DES encryption types.
See also [RFC4401] for generic security considerations of
GSS_Pseudo_random().
See also [RFC3961] for generic security considerations of the
Kerberos V cryptographic framework.
Use of Ticket session keys, rather than sub-session keys, when
initiators and acceptors fail to assert sub-session keys, is
dangerous as ticket reuse can lead to key reuse; therefore,
initiators should assert sub-session keys always, and acceptors
should assert sub-session keys at least when initiators fail to do
so.
The computational cost of computing this PRF+ may vary depending on
the Kerberos V encryption types being used, but generally the
computation of this PRF+ gets more expensive as the input and output
octet string lengths grow (note that the use of a counter in the PRF+
construction allows for parallelization). This means that if an
application can be tricked into providing very large input octet
strings and requesting very long output octet strings, then that may
constitute a denial of service attack on the application; therefore,
applications SHOULD place appropriate limits on the size of any input
octet strings received from their peers without integrity protection.
Williams Standards Track [Page 3]
RFC 4402 A PRF for the Kerberos V Mechanism February 2006
5. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2743] Linn, J., "Generic Security Service Application Program
Interface Version 2, Update 1", RFC 2743, January 2000.
[RFC2744] Wray, J., "Generic Security Service API Version 2 :
C-bindings", RFC 2744, January 2000.
[RFC3961] Raeburn, K., "Encryption and Checksum Specifications for
Kerberos 5", RFC 3961, February 2005.
[RFC4121] Zhu, L., Jaganathan, K., and S. Hartman, "The Kerberos
Version 5 Generic Security Service Application Program
Interface (GSS-API) Mechanism: Version 2", RFC 4121,
July 2005.
[RFC4401] Williams, N., "A Pseudo-Random Function (PRF) API
Extension for the Generic Security Service Application
Program Interface (GSS-API)", RFC 4401, February 2006.
Author's Address
Nicolas Williams
Sun Microsystems
5300 Riata Trace Ct
Austin, TX 78727
US
EMail: Nicolas.Williams@sun.com
Williams Standards Track [Page 4]
RFC 4402 A PRF for the Kerberos V Mechanism February 2006
Full Copyright Statement
Copyright (C) The Internet Society (2006).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Acknowledgement
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
Williams Standards Track [Page 5]