Mark
Please find responses inline. Thanks for the review.
regards, Frederick
Frederick Hirsch
Nokia
On Apr 7, 2009, at 2:27 AM, ext Priestley, Mark, VF-Group wrote:
Hi Art, All,
Please find below my editorial comments and requests for
clarifications
based on the new WD [1]. While it is a long list the comments are all
minor and so hopefully easily addressed. Overall I think the spec is
looking good, for which a lot of thanks must go to Frederick and
Marcos!
That said, I have a couple of more substantive comments that I will
send
in the next couple of days.
Many thanks,
Mark
[1] http://www.w3.org/TR/2009/WD-widgets-digsig-20090331/
-----
COMMENTS
-----
1.0
"A widget package can be signed by the author of the widget
producing an
[XMLDSIG11] signature that cryptographically includes all of the file
entries other than signature files. A widget package can also be
signed
by one or more distributors, with XML signatures that each
cryptographically includes all of the non-signature file entries as
well
as any author signature."
Change the last sentence for consistency between definitions, ie:
"... A widget package can also be signed by one or more distributors
<change> of the widget, producing [XMLDSIG11] </change> signatures
that
each cryptographically includes all of the non-signature file
entries as
well as any author signature."
ok
-----
Can we remove the following sentence? This is a general property of
signatures which I'm not sure we need to include.
"Digitally signing implies use of private key material only known by
the
signer, thus enabling verification of integrity and signature source."
ok
-----
1.1
We don't actually define any XML elements in the
"http://www.w3.org/ns/widgets-digsig"; namespace... is this worth
noting
this and/or removing the "wsig" prefix?
We define URIs using this namespace so we should keep the URI
definition.
ok with removing prefix since it is not used now but would prefer to
keep to avoid errors later. Not a big issue to remove though.
-----
The terms "XML elements" and "resources" seem to be used
interchangeably? Is there a difference?
yes, one is xml elements others are resources as referenced by URI
-----
"Algorithms used by XML Security are defined in a number of
places..." -
could we tighten up this sentence, eg something like "This
specification
references algorithms defined in [XMLSecAlgs] and [XMLDSIG11]" ?
No, XMLSecAlgs does not define the algs. There are defined in a number
of places :)
-----
1.2
"compressed (or Stored)" - either remove capitalisation of Stored or
add
it to compressed
I suggest "stored". Marcos?
-----
"physical file" -> file ?
Marcos? ok with file personally
-----
"top-most path level" - is there a better way of saying this?
don't think so unless you have a proposal without using the word "root"
-----
"which MAY logically contain" - if the configuration file is made
mandatory then the MAY should be a MUST
I think it is a MAY, others?
-----
Question: is a file entry the same as a file? If so then we should
always use "file entry" in place of "file". If not then perhaps we
should define file?
I don't think they are the same. This is a P&C question. Marcos?
-----
"(i.e., a third party that is distributing the widget on behalf of the
author)." - in some cases the author may also be (one of) the
distributor(s). suggest changing "i.e." to "e.g."
I think i.e. is correct. In the case you suggest they just happen to
be the same entity fulfilling two roles.
-----
3
"As well as sections marked as non-normative, examples and notes in
this
specification are non-normative. Everything else in this specification
is normative. The security considerations section is non-normative."
Suggest change to the following for readability:
"As well as sections marked as non-normative, the examples and notes,
and security considerations in this specification are non-normative.
Everything else in this specification is normative."
yes, better.
-----
4
"This section defines how to locate digital signatures in a widget
package for processing. An implementation MUST achieve the same result
as the following algorithm used to locate digital signatures in a
widget
package:"
In the sentence above, change "digital signatures" to "signature
files"
(in both cases)
ok
-----
"This MAY be determined by the security policy used by the user
agent."
Can we say will or, better yet, SHOULD or MUST? Otherwise, what do we
mean when we say MAY? Who (what) else may enforce security policy?
we mean may since security policy is out of scope. How can we mandate
what is not defined?
-----
"Thus the highest numbered distributor signature would be validated
first."
Change to:
"Thus in the case that one or more distributor signatures were
validated, the highest numbered distributor signature would be
validated
first."
ok
-----
5.1
"A widget package MAY be digitally signed using XML Signature
[XMLDSIG11]."
don't we mean:
"A widget package MAY be digitally signed using the profile of XML
Signature [XMLDSIG11] defined by this specification." ?
ok
-----
As this section is talking about generating a signature, I suggest
that
we remove "and validated" in the following sentence:
"Each signature file MUST be generated and validated in"
No - 6.1 applies to both generation and validation, common to both.
-----
5.2
As per previous email exchange we need to re-work author signature
definition
-----
"zero or one author signatures." - remove final "s"
No, I think that the current is correct grammatical usage and clear in
meaning.
-----
"This represents the digital signature of the author of the widget
package."
add "signature file" ie "This signature file represents the digital
signature of the author of the widget package."
ok
-----
5.3
"This represents the digital signature of a distributor of the widget
package."
add "signature file" ie "This signature file represents the digital
signature of a distributor of the widget package."
ok
-----
5.3.1
"Within a widget package these signature files MUST be ordered based
on
the numeric portion of the signature file name.
Thus, for example, signature2.xml precedes signature11.xml."
Question: what does this mean? What is it requiring from a widget
package?
-----
5.4
"Implementations MUST be prepared to accept X.509 v3 certificates
[RFC5280]."
Can we say "User agents" rather than implementations
we mean implementations
-----
5.5
"It MUST be unique for a given signer."
Do we need to make it clear that we are not expecting the UA to check
this? I take it we're not asking the UA to check this, right?
What do you suggest we say?
-----
7.1
"Each ds:Signature property" -> "Each ds:SignatureProperty" ?
meant as written since wanted to be clear about properties as opposed
to XML representation.
-----
In step 5 there is no bullet for digest algorithms, which there
probably
should be.
I believe digest algorithms are mentioned for ds:References for the
digesting of content, but not needed in step 5 since the signature
method includes the digest method (eg RSAwithSHA256)
-----
7.2
"This MUST be a unique signing string for all signature files
created by
the signer." - same comment as 5.5. ie - Do we need to make it clear
that we are not expecting the UA to check this?
What do you suggest we say?
-----
7.3
"If signature file validation fails for any reason, any external
entities (e.g., a user agent that implements [Widgets Packaging])
relying on the validation of the signature file MUST be notified of
the
failure..."
Maybe we should say that notification of successful validation must
also
be provided?
Add before the last paragraph?:
If signature validation is successful any external entities (e.g., a
user agent that implements [Widgets Packaging]) relying on the
validation of the signature file MUST be notified of the success.
-----
8
"A signature file may also be renamed, which can affect processing."
suggest modification to "...which can affect the order in which
distributor signatures are processed"
ok
-----
9.1.1
"Upon signature generation, if this property is used, the value is set
to ..."
Is inconsistent with the sentence from 5.1 which states:
"Each signature file MUST contain a dsp:Identifier signature
properties
element compliant with XML Signature Properties [XMLDSIG-Properties]
and
this specification."
this is not inconsistent. Section 9 says if used, section 5.1 says it
is used in the profile...
Suggest deletion of ", if this property is used," from the first
sentence
I do not think I understand the rationale for this change.
-----
9.1.2
"Profiles MUST specify details of the identifier property value
creation
and interpretation." What does "Profiles" mean in this sentence
the widgets signature specification is a profile...
-----
"If multiple instances of this property are found on a single
signature,
then applications MUST NOT deem any of these properties valid." -
which
would in turn mean that the signature was invalid, right? We may
want to
state this?
the properties are not valid though the signature still might be
valid. Interpretation of properties is profile dependent.
-----
9.2
Note that the same comments may apply to 9.2.1 and 9.2.2 dependent on
the discussions on the mandatory/optional status of this property.
same answers as for 9.1.2
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Arthur Barstow
Sent: 02 April 2009 17:21
To: public-webapps
Subject: [widgets] New WD of Widgets 1.0: Digital Signatures
spec published on March 31
On March 31 a new WD of the Widgets 1.0 Digital Signature spec
was published and announced on the W3C's home page:
[[
2009-03-31: The Web Applications Working Group has published a
Working Draft of Widgets 1.0: Digital Signatures. This
document defines a profile of the XML Signature Syntax and
Processing 1.1 specification to allow a widget package to be
digitally signed.
Widget authors and distributors can digitally sign widgets as
a trust and quality assurance mechanism. Prior to
instantiation, a user agent can use the digital signature to
verify the integrity of the widget package and perform source
authentication. This document specifies conformance
requirements on both widget packages and user agents.
]]
Please review this new WD as soon as possible, preferably
within the next two weeks:
<http://www.w3.org/TR/2009/WD-widgets-digsig-20090331/>
-Regards, Art Barstow
