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W3C XMLP WG review of WSS committee specs

From: Marc Hadley <Marc.Hadley@Sun.COM>
Date: Wed, 15 Oct 2003 15:01:38 -0400
To: wss-comment@lists.oasis-open.org
Cc: xml-dist-app@w3.org
Message-id: <01521360-FF42-11D7-A2CD-0003937568DC@sun.com>

Please find attached the W3C XMLP WGs review of the Web Services  
Security committee specifications.

Regards,
Marc Hadley (on behalf of the W3C XML Protocol Working Group)


Web Services Security - W3C XMLP WG Review
------------------------------------------

This review refers to the Web Services Security committee  
specifications linked from the WSS TC homepage at:

http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=wss

The comments follow document order and indicate the sections of the  
document and line numbers where appropriate. Significant/serious issues  
are called out with ***, other issues are mainly editorial in nature.


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Web Services Security: SOAP Message Security
--------------------------------------------

This review refers to Web Services Security: SOAP Message Security  
located at
http://www.oasis-open.org/committees/download.php/3281/WSS- 
SOAPMessageSecurity-17-082703-merged.pdf

General
Needs a good proofreading session. There are numerous grammatical and  
punctuation errors, some of which are noted below.

*** SOAP 1.2 is the "Recommendation"-level version of SOAP, and we  
believe
that WSS should be clear in its support for SOAP 1.2 as well as SOAP  
1.1.
Furthermore, among the changes that we believe to be improvements in  
SOAP
1.2 was the more careful use of terminology and the more careful
presentation of a rigorous processing model.  While we clearly  
understand
the need for WSS to support SOAP 1.1 as well as SOAP 1.2, we strongly  
urge
you to use SOAP 1.2 terminology wherever possible for abstractions such  
as
nodes, intermediaries, roles, etc.  We furthermore encourage you to  
refer
wherever appropriate to the SOAP 1.2 processing model, faults, etc.  In
many cases we believe that this will aid not just in the use of WSS with
SOAP 1.2, but in the precise presentation of the use of WSS with SOAP  
1.1
as well (since in many cases SOAP 1.1 has no precise explanation of  
terms
that are carefully introduced in SOAP 1.2.)  Where SOAP 1.1 differs in  
its
useage or terminology from SOAP 1.2, we suggest that you clearly explain
the use of WSS in both environments.

Despite referring to SOAP 1.2, most, if not all, of the examples and  
namespace URIs are taken from previous versions of SOAP or early drafts  
of the SOAP 1.2 Recommendation - a pass through the document to ensure  
alignment with the SOAP 1.2 Recommendation is required.

Status
The TC home page describes documents that have achieved committee spec  
status. However the link points to a document whose status section  
indicates it is an 'interim draft'. Shouldn't the status section  
reflect the committee spec status ?

Abstract
"No specific type of security token is required the specification is  
designed to be extensible (e.g. support multiple security token  
formats).": insert a comma after 'required', change 'e.g.' to 'i.e. to'.

1. Introduction

*** The introduction talks about SOAP extensions. For consistency with  
SOAP 1.2, it should instead use the SOAP 1.2 terminology of features  
and modules. See section 3 of SOAP 1.2 Part 1.

110 "This specification provides three main mechanisms: ability to send  
security token as part...": 'a security token' or 'security tokens'.

1.1.1 Requirements

139, looks like this should be part of the bulletted list rather than a  
standalone paragraph.

2. Notational Conventions
Throughout the document certain words and phrases are highlighted in  
blue or red. E.g. the word SOAP is often highlighted in blue. There is  
no mention of any notational convention applicable to this coloring so  
its not clear if it has any particular meaning or intent. When printed  
in black and white its unlikely that such color information will be  
visible so it would be better to use some other typographic convention,  
e.g. italics or bold. On further reading it seems that blue coloring is  
intended to convey a bibiographic citation - a better means of  
indicating this is required.

Lines 150-155 seem to be in a different font though the reason for this  
is unclear.

2.2 Namespaces

*** 170, 171: Its surprising to see the WSS namespace URIs using the  
xmlsoap.org domain. This domain is the property of Microsoft Corp and  
they maintain control over what such namespace URI resolve to. For an  
OASIS standard one would expect namespace URIs to use the  
oasis-open.org domain instead.

175: Update the soap namespace to use the one from the SOAP 1.2  
Recommendation.

2.3 Terminology

*** 185 "End-To-End Message Level Security - End-to-end message level
security is established when a message that traverses multiple
applications within...": We have suggested above the careful use of
SOAP 1.2 terminology, and we believe that this paragraph is
an example.  SOAP 1.2 defines the SOAP message path as "The set of SOAP
nodes through which a single SOAP message passes. This includes the  
initial
SOAP sender, zero or more SOAP intermediaries, and an ultimate SOAP
receiver." A single SOAP message doesn't traverse multiple applications
unless they are SOAP intermediaries, if they are not then each
application-application interaction is effectively a separate SOAP
message exchange.

3.2 Message Protection

252 "This document defines syntax and semantics of signatures within  
<wsse:Security> element.": 'a ... element' or 'the ... element'.
253 "This document does not specify any signature appearing outside of  
<wsse:Security> element.": 'a ... element' or 'the ... element'.

*** SOAP 1.2 is XML Infoset based, SOAP bindings are required to  
preserve SOAP message infosets when transferring messages. In order to  
properly integrate with SOAP 1.2, the SOAP Message Security  
specifications need to be recast in Infoset terms. Note that this does  
not require wholesale adoption of Infoset terms throughout the  
document; the WSS spec could just include a suitable note in the  
terminology section, e.g.:

"SOAP 1.1 was expressed in terms of XML 1.0 and made only general
provisions for alternate network transports or for alternate
representations of XML on the wire by the corresponding bindings.  SOAP
1.2 makes such capabilities more explicit by modelling the XML Envelope  
as
an Infoset, and explicitly granting license to bindings to use non-XML  
1.x
representations on the wire (e.g. compressed, encrypted,  
binary-optimized,
etc.)  if desired.  Except in situations where the differences are
important, this WSS specification makes no explicit distinction between
the SOAP 1.1 and SOAP 1.2 formulations.  A reference to a <soap:header>
element, for example, should be understood as referring to the
corresponding Infoset Element Information Item when SOAP 1.2 is being
used."

If there are particular cases where the distinction is important, then  
you should of course deal with it explicitly so your users will know  
how to use WSS with SOAP 1.1 and SOAP 1.2 respectively. For example, it  
would be worth giving some thought to which layers of WSS will work  
with approaches such as MTOM, which use the power of the Infoset  
formulation to enable certain optimizations.

Adoption of this approach will require the WSS specification to  
normatively state the mapping from XML Infoset to the data object  
(typically an XPath nodeset) used as input to the constituent  
cryptographic operations (e.g. C14N).

3.3 Invalid or Missing Claims

255 "The message recipient SHOULD reject a message with an invalid  
signature, a message that is missing necessary claims and a message  
whose claims have unacceptable values as such messages are unauthorized  
(or malformed) message..": Bad grammar, replace with something like "A  
message recipient SHOULD reject messages containing invalid signatures,  
messages missing necessary claims or messages whose claims have  
unacceptable values. Such messages are unauthorized (or malformed)."

3.4 Example

Example uses a SOAP 1.1 envelope, change to use SOAP 1.2.

5 Security Header

400 "The <wsse:Security> header block provides a mechanism for  
attaching security-related information targeted at a specific recipient  
in a form of a SOAP role.": change 'in a form of a' to 'in the form of  
a'.

*** 406 "a message MAY have multiple <wsse:Security> header blocks if  
they are targeted for separate recipients." why can't a message contain  
multiple wsse:Security header blocks targetted at the same recipient,  
this seems like an uneccessary/arbitrary restriction. In addition it  
requires intermediaries to modify header blocks not targetted at them  
if they wish to insert security information targetted at a role for  
which there already exists a wsse:Security header block. An alternative  
design leveraging the role, relay capabilities of SOAP 1.2 is  
recommended.

*** 410 "The <wsse:Security> header block without a specified S:role  
MAY be consumed by anyone, but MUST NOT be removed prior to the final  
destination or endpoint." What does 'consumed' mean. SOAP 1.2 makes it  
clear that SOAP headers without a role attribute are equivalent to  
those with a role of  
"http://www.w3.org/2003/05/soap-envelope/role/ultimateReceiver". In  
both cases the ultimate receiver of the message is the target of the  
header block.

*** 450 "All compliant implementations MUST declare which profiles they  
support": how must they declare this ? This seems like an untestable  
assertion and should probably be dropped.

*** 455 "The optional mustUnderstand SOAP attribute on Security header  
simply means you are aware of the Web Services Security: SOAP Message  
Security specification, and there are no implied semantics.": No ! The  
mustUnderstand attribute has the semantics as defined by the SOAP 1.2  
specification. All SOAP nodes MUST abide by the SOAP processing model  
including generation of mustUnderstand faults if the header block is  
not understood. SOAP modules and features cannot override these  
semantics.

6.2 Username Token

495 "This is an extensibility mechanism to allow additional attributes,  
based on schemas, to be the <wsse:Username> element.": change 'to be  
the' to 'to be added to the'.

*** 503 "All compliant implementations MUST be able to process a  
<wsse:UsernameToken> element." The element is extensible, what should  
compliant implementations do with extensions they don't understand -  
ignore them, fault, ... Such extensibility semantics must be defined  
for all extensible elements, just making things extensible isn't  
sufficient.

506 Change example to use SOAP 1.2 envelope instead of SOAP 1.1.

6.3 Binary Security Tokens

545 "This attribute is extensible using XML namespaces.": Confusing,  
the attribute isn't extensible in itself, but its value could be said  
to be extensible though really just saying the attributes type is a XML  
qualified name is probably sufficient.

*** 548 /wsse:BinarySecurityToken/@EncodingType: this seems to be  
reinventing XML schema to a certain extent. Wouldn't it be better to  
allow child elements of BinarySecurityToken, one per type of encoding,  
that way a schema processor can verify the contents on behalf of the  
wsse processor.

*** Also, why use qualified names instead of URIs for identifying  
encoding types. URIs don't have the problem of maintaining namespace  
prefixes that demands the ns declaration location requirements outlined  
in this section. Use of qualified names in element and attribute values  
complicates things...

*** 558 "All compliant implementations MUST be able to process a  
<wsse:BinarySecurityToken> element.": same comment as for  
UsernameToken, what should an implementation do with a token of unknown  
type or one containing an extension that is not understood.

6.4 XML Tokens

*** 578 "This section presents the basic principles and framework for  
using XML-based security tokens." Is this section complete ? There's no  
trace of any principles or a framework.

7.1 SecurityTokenReference Element

*** Same comment as for BinarySecurityToken re extensibility semantics  
and requiring all implementations to be able to process the element.

8.1 Algorithms

*** Surprised that there is no mention of SOAP Message Normalization  
(sop12-n11n) here:  
http://www.w3.org/TR/2003/NOTE-soap12-n11n-20030328/. How does SOAP  
Message Security cope with the variations that soap12-n11n aims to  
removes from messages ?

*** 832 "Finally, if a sender wishes to sign a message before  
encryption, they should alter the order of the signature and encryption  
elements inside of the <wsse:Security> header.": alter in what way,  
this needs to be more specific.

839 "care MUST be taken in creating a signing policy that requires
signing of parts of the message that might legitimately be altered in  
transit.": shouldn't this say "care MUST be taken not to create a  
signing policy that requires signing of parts of the message that might  
legitimately be altered in transit." ?

841 "SOAP applications MUST satisfy the following conditions: The  
application MUST be capable of processing the required elements defined  
in the XML Signature specification.": SOAP applications or WSS  
implementation ? The latter is used elsewhere in the specification.

*** 855 "If overall message processing is to remain robust,  
intermediaries must exercise care that their transformations do not  
affect of a digitally signed component.": again a reference to  
soap12-n11n would seem to be in order here. Intermediaries are allowed  
to perform certain transformations, rather than implying the need for  
additional restrictions on intermediaires it seems more realistic to  
require normalization of the effects of such legal transformations.

9 Encryption

1026 "The combined process of encrypting portion(s) of a message and  
adding one of these a sub-elements is called an encryption step  
hereafter.": remove the 'a' between 'these' and 'sub-elements'.

9.3.1 Encryption

*** The suggested process for performing encryption would only include  
the data from the original message that was encrypted. All other data  
would be ommitted, suggest adding an additional step to copy in all the  
non-encrypted data.

*** 1166 "Parts of a SOAP message may be encrypted in such a way that  
they can be decrypted by an intermediary that is targeted by one of the  
SOAP headers. Consequently, the exact behavior of intermediaries with  
respect to encrypted data is undefined and requires an out-of-band  
agreement.": more detail required, why is the behaviour undefined ?  
Surely the intermediary would decrypt the parts as instructed by the  
corresponding header block ?

12 Error Handling

*** The specification should define the values of the  
Fault/Reason/Text, Fault/Code/Value and Fault/Code/Subcode/Value EIIs.  
Presumably the defined codes are the allowable values of the  
Fault/Code/Subcode/Value EIIs ? What values should be used for each  
code in the corresponding Fault/Reason/Text, Fault/Code/Value EIIs ?

16 References

1545 [SOAP12] W3C Working Draft, 26 June 2002: This should be updated  
to point to the SOAP 1.2 Recomendation.



Web Services Security: UsernameToken Profile
-------------------------------------------

This review refers to Web Services Security: UsernameToken Profile  
located at
http://www.oasis-open.org/committees/download.php/3154/WSS-Username-04- 
081103-merged.pdf

General

Needs a thorough proof reading session. Throughout the document certain  
words and phrases are highlighted in blue. E.g. the word SOAP is often  
highlighted in blue. There is no mention of any notational convention  
applicable to this coloring so its not clear if it has any particular  
meaning or intent. On further reading it seems that blue coloring is  
intended to convey a bibiographic citation - a better means of  
indicating this is required. In some places the common [nn] format is  
used for citations, the document should adopt a single consistent style  
throughout. Note that none of the [nn] citations are actually listed in  
the references section of the document !

Status
The TC home page describes documents that have achieved committee spec  
status. However the link points to a document whose status section  
indicates it is an 'interim draft'. Shouldn't the status section  
reflect the committee spec status ?

2. Notations and Terminology

2,1 Notational Conventions (should this be 2.1 - ie '.' instead of ',')  
?

Lines 54-59 seem to be in a different font though the reason for this  
is unclear.

67 "The current SOAP 1.2 namespace URI is used herein...": an old URI  
is used, needs updating to refelct the ns URI of the SOAP 1.2  
Recommendation.

3. Terminology

Repeats much of the text from section 2 ! It looks to me like section 3  
should be a subsection of section 2. The repeated text needs to be  
removed.

3 UsernameToken Extensions

87 Section number seems to be 'compromised'. There are two section 3s  
and two section 4s ! Renumbering required. None of the subsections of  
the second section 3 are numbered - is this deliberate ?

93 "providing": the letters 'd' and 'i' are colored purple for some  
reason.

99 "For example, if a server does not have access to the clear text of  
a password but does have the hash, then the hash is considered a  
password equivalent and can be used anywhere where a "password" is  
indicated in this specification.": its not clear from this description  
whether such a hash should be contained in a wsse:PasswordText or  
wsse:PasswordDigest typed Password element ?

Also note that the formatting of element names and types is not  
consistent. In some places a fixed width font is applied, in others no  
formatting is used. Is there any significance to such formatting  
chnages or does the document just need a consistency check ?

106 "..": there are quite a few instances of double full stops  
throughout the document, a simple search and replace of ".." for "." is  
required.

126 "1. First, it is recommended that web service providers reject any  
UsernameToken not using both nonce and creation timestamps.":  
recommended or RECOMMENDED as per RFC 2119 ? Same comment for next two  
points in the list and elsewhere in the document. Its not clear whether  
'recommended' is being used in the RFC 2119 sense or not. Suggest  
adopting the notations as described in section 2 (and again in the  
first section 3).

186, 204 Both examples use out of date SOAP 1.2 namespace URIs.

References

A number of out of date references are listed including SOAP 1.2 and  
XML Encryption. These should be updated to reflect the latest versions.



Web Services Security: X.509 Token Profile
------------------------------------------

This review refers to Web Services Security: X.509 Token Profile  
located at
http://www.oasis-open.org/committees/download.php/3214/WSS- 
X509%20draft%2010.pdf

General
Despite referring to SOAP 1.2, most, if not all, of the examples and  
namespace URIs are taken from previous versions of SOAP or early drafts  
of the SOAP 1.2 Recommendation - a pass through the document to ensure  
alignment with the SOAP 1.2 Recommendation is required.

Status
The TC home page describes documents that have achieved committee spec  
status. However the link points to a document whose status section  
indicates it is an 'interim draft'. Shouldn't the status section  
reflect the committee spec status ?

2.1 Notational Conventions

142 "This document uses the notational conventions defined in SOAP  
Message Security [WS-Security].": SOAP Message Security is colored  
blue, the reason for this isn't clear. I suspect its something related  
to the following citation, but that is already captured in the  
[WS-Security].

148 "The XML namespace URIs": XML namespace is colored blue, perhaps  
this should be followed by [XML-ns] ? Further occurances of this are  
not noted, the editors need to settle on a single citation format.

151, 152 Its surprising to see the WSS namespace URIs using the  
xmlsoap.org domain. This domain is the property of Microsoft Corp and  
they maintain control over what such namespace URI resolve to. For an  
OASIS standard one would expect namespace URIs to use the  
oasis-open.org domain instead.

153 The SOAP namespace is out of date, needs updating to the SOAP 1.2  
Recommendation namespace.

238, 285, 362 Update envelope namespace to SOAP 1.2 Recommendation  
namespace

3.3.1 Key Identifier

233 "Consequently implementations that use this form of reference  
within a signature SHOULD employ the wsse:SecurityTokenReference  
deferencing transform within a core barename XPointer reference to the  
signature key information in order to ensure that the referenced  
certificate is signed, and not just the ambiguous reference.":  
Editorial s/deferencing/dereferencing/. This could do with some  
rewording to make the intent clear, spelling out exactly what is being  
recommended (signing the ds:KeyInfo via an Xpointer reference along  
with the actual data to be signed ??). Also a reference to the  
definition of the wsse:SecurityTokenReference dereferencing transform  
would be useful here.

4 References

It would be useful to give URLs to those referenced specifications that  
are available online.

417 SOAP reference is to SOAP 1.1, should be to SOAP 1.2 Recommendation.

426, 427 references need to be filled in.
Received on Wednesday, 15 October 2003 15:01:40 GMT

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