Feedback on the use of the DSS visible signature profile

[Ernst Jan van Nigtevecht <EJvN@Sonnenglanz.net>]

Dear TC-members,

Below some feedback on the use of the visible signature profile.

With kind regards

Ernst Jan

===============
Related to the DSS Core:

(1) Regarding message validation by means of XSD's: The OptionalInputs / 
OptionalOutputs are defined as anyType. The OptionalInputs and 
OptionalOutputs can appear in any order:

DSS-Core Line 615: "Applications MUST be able to handle optional inputs 
or outputs appearing in any order within these elements. Normally, there 
will only be at most one occurrence of any particular optional input or 
output within a protocol message."

Usually, an XSD defines elements in a particular order. Consequently, 
you cannot define an XSD for this. To validate a request, the part of 
the OptionalInputs will always succeed, even though the actual sub-tree 
does not adhere to a specific optional input XSD.

Question 1:
The XSD of a particular OptionalInput / OptionalOutput will be 
specified, but how can one easily validatie a message using the dss xsd 
and the profile specific xsd? It currently seems that you have to 
manipulate the dss xsd to incorporate the OptionalInputs xsd (leaving 
out the anyType for the OptionalInput, but that invalidates "any order").

It could have been stated that the order of the OptionalInputs / 
OptionalOutputs has to be alphabetically.

What is the experience of other implementers?


===============
Related to DSS profile visual signatures:

(2) It seems that the ServicePolicy is not yet used. Instead, some 
profiles define their own policy elements.

DSS-Core: 2.8.1 Optional Input <ServicePolicy>

DSS-profile-visualsig: 4.1.1.2.1.2 Optional Input <VisibleSignaturePolicy>

Question 2:
Why has that been done?


(3) If a DSS profile is defined, a value is defined for the profile 
attribute. The visual-sig profile states:

DSS-profile-visualsig 3.1.3 Relationship to Other Profiles
"This profile provides means for the explicit management of signature 
policies with [DSSCore] and other existing profiles like [AdES-DSS], and 
as such, it may be used in conjunction with these specifications."

Question 3:
What does the phrase "may be used in conjunction with these 
specifications" actually mean? How can one specify the use of two 
profiles in one and the same SignRequest (the profile attribute value 
can only hold one value).

(4) Creation of multiple signature fields

Currently, the newly defined OptionalInput can occur 0..unbounded times, 
besides other optional input (from other profiles).

Question 4:
For ease of XML validation, and code generation (especially Java), it 
would be good to define 1 (new) element containing 1 or more elements 
defining the (currently defined) visible signatures.

The OptionalInput for the visible signature profile will consist of 1 
single element. (This principle should be used by other profiles as 
well..  :-)

Proposal A:
The OptionalInput for the visible signature profile will consist of the 
element:
<VisibleSignatures>

The type defines an element consisting of a choice, consisting of
<VisibleSignatureProfile> element,
<VisibleSignatureConfigurations> element (as already defined in the 
current visible signature profile)

The <VisibleSignatureProfile> provides a name for a visible signature 
profile id, to be used during document submission (and certification).

(5) We would like to be able to use the profile for the following scenario:

* The DSS client creates a SignRequest with information about the 
signature fields and the field that has to be used for certification
* The DSS server creates the indicated fields and signs (certifies) the 
document (using the indicated field).
* The DSS server delegates the signing operation of the other signature 
field(s) to an application (an applet for instance). An enduser will 
sign a certain field
* The DSS server creates a SignResponse

Proposal B:
The OptionalOutput defines a means to indicate which signature field has 
been signed (in DSS delegates the actual signature operation to an 
applet by which the enduser will select a field and creates a signature).

An optional output would consist of an element
<VisibleSignatures> containing, one or more elements:

<VisibleSignature> consisting of a
<FieldName> which specifies a name of the field and an attribute 
isSigned (boolean).