Re: [egov] Re: Secure Workflow. Was: [egov] "Dry" and "Wet" signatures- A definition

[Duane Nickull <dnickull@adobe.com>]

Anders:

LOL ;-)  You are preaching to the converted.  Adobe has actually 
released a complete workflow engine as a core part of its liveCycle.

It seems from this thread that there is a lot of interest in this 
topic.  Is your intention to set up a separate TC and list serve for 
this effort?  I would be interested in continuing.

best wishes (from Stockholm West)

Duane

Anders Rundgren wrote:

> Ed,
> In your description of the purchasing process, you left out the 
> information (workflow) system.  In my opinion, information systems 
> today constitute the core of IT, and should due to this influence how 
> you structure and control, not only data, but processes, roles etc.
>  
> By using client-based PKI security, you can indeed extend 
> authentication beyond your own systems as your rightfully claim.   The 
> dark side of this superficially very tempting perspective, is major 
> inflexibility, high costs, limited scalability, privacy issues, and a 
> multitude of "very promising PKI pilots". 
>  
> If we again take the US federal agencies (who have toiled with FPKI 
> for more than a decade), they for some reasons, AFAIK, to date do 
> not publish certificates, in spite of being a prerequisite for 
> handling encryption the way you describe.  SSL/TLS has due to this 
> become the de-facto way of encrypting transactions between 
> organizations, at least for POs.
>  
> Apparently even some US public sector entities have recently begun to 
> realize that the end-to-end PKI paradigm is not delivering, which can 
> be seen in the following document: 
> http://middleware.internet2.edu/pki05/proceedings/kailar-phinms.ppt which, 
> somewhat ironically, was initially shown in NIST's facilities, the 
> very home of FPKI.
>  
> My proposed charter for a WebSign standardization effort is therefore 
> targeting a world "controlled" by information systems.  Furthermore, I 
> would favor a scheme that addresses the volume market which is signing 
> off day-to-day tasks like on-line bank payments, PO attestations, 
> income tax declarations, and doctor appointments.  It does in no 
> way have to stop there, but this is where it should start.
>  
> regards
> Anders Rundgren
> Working for a major US computer security company but here acting as an 
> individual
>  
> ----- Original Message -----
> *From:* Ed Chase <mailto:chase@adobe.com>
> *To:* John Messing <mailto:jmessing@law-on-line.com>
> *Cc:* Duane Nickull <mailto:dnickull@adobe.com> ; eGov OASIS 
> <mailto:egov@lists.oasis-open.org> ; Anders Rundgren 
> <mailto:anders.rundgren@telia.com>
> *Sent:* Monday, August 29, 2005 20:08
> *Subject:* Re: [egov] Re: Secure Workflow. Was: [egov] "Dry" and "Wet" 
> signatures - A definition
>
> John -
>
> It seems that you're suggesting that you can establish authenticity 
> without identity. I would disagree. At some point you have to 
> establish trust with a system, individual, or organization through 
> some means - whether this is internal authentication or PKI digital ID 
> it's the same concept. Trust has to be established either explicitly 
> or implicitly. PKI signatures just offer the opportunity to extend 
> authentication beyond your own systems. While an ebXML registry could 
> certainly categorize the information in the messages, it doesn't 
> really address any issues of trust between the parties.
>
>
> With regard to secure transactions & PKI -
>
> For transactions like the purchase order example that start internal 
> and later become external, why not use PKI from the start and employ 
> policy mapping between organizations or a bridge? Certificate policy 
> mapping (for limited sized communities) or a PKI bridge would give the 
> trading partners interoperability on both the authenticity and 
> security fronts. How about something like this:
>
> 1) Include PKI policy-mapping with business partner agreements and/or 
> take advantage of a PKI bridge.
> 2) Create a your forms in PDF or an XHTML document variant that's 
> based on your industry standard for exchange - UBL or whatever.
> 3) Users complete the form or application and sign both presentation 
> and data with their digital identity. If it's a PDF, the signature is 
> embedded within the document, and you can also embed the revocation 
> status of your credential at sign-time for long-term validation.
> 4) Encrypt the document for the recipient's specific digital ID if 
> required and send the document
> 5) The document is protected regardless of transport. Having a PKI 
> relationship with your trading partner allows your signatures to be 
> validated by the recipient.
>
> The majority of this can be automated. Signing and validation can be 
> server-centric if required. Everything you need for auditable long 
> term validity is self contained within the document and possessed by 
> both parties. The PKI layer is also self-contained and well removed 
> from the process. You don't have to worry about transport or 
> individual authentication requirements for different trading partners.
>
> Ed
> -- 
> <http://www.adobe.com>Ed Chase
> Worldwide Standards
> Adobe Systems, Inc.
> chase@adobe.com
> 703.883.2830
>
> John Messing wrote:
>
>>A secure audit trail can be accomplished with tamper-evident
>>technologies and may have value even when a logical association with a
>>human or legal entity as a signer in a conventional sense is not
>>necessary or desired (e.g., to document log events securely). Where
>>such logical association with signers is required for purposes of legal
>>enforceability, then it can be considered as a subset of the secured
>>workflow generally. Componentizing documents into strings and metadata
>>can overcome many of the archival issues that have been alluded to but
>>rarely confronted directly. Tamper-evident technologies need not
>>include PKI, or even traditional digital signatures, but should take
>>into account recent Chinese contributions to hashing technologies and
>>their weaknesses. ebXML repository technology may prove to be very
>>useful in this context. Whether retention of copies of original
>>documents in original format will be required remains to be seen.
>>
>>The American Bar Association adopted guidelines in August 2005 for Court
>>Automation that incorporate many of these notions.
>>
>>John Messing
>>American Bar Association Science and Technology Law Representative to
>>OASIS and LegalXML-OASIS.
>>
>>  
>>
>>>-------- Original Message --------
>>>Subject: [egov] Re: Secure Workflow. Was: [egov] "Dry" and "Wet"
>>>signatures - A definition
>>>From: Duane Nickull <dnickull@adobe.com>
>>>Date: Mon, August 29, 2005 8:02 am
>>>To: Anders Rundgren <anders.rundgren@telia.com>
>>>Cc: eGov OASIS <egov@lists.oasis-open.org>
>>>
>>>Anders:
>>>
>>>I understand your intent better after this email.  My points are:
>>>
>>>1.Steps 2 and 3 of your secure workflow below are the only methodology 
>>>that should be employed.  One should not presume that any "document" 
>>>will never be modified and always perform some type of checksum() 
>>>operation before validating a signature.  The signed content should 
>>>always be auditable.
>>>
>>>2. There is no need to stop at the document level, DSig methodologies 
>>>are significantly complex today, even allowing signing of a partial 
>>>sub-set of a document.  Therfore, documents can contain both mutable and 
>>>immutable content.  Logically, if you only look at a "document" and some 
>>>part of it is mutable, you always have to declare the entire document 
>>>mutable.  I would advocate migrating from "document" to "content" or 
>>>components that make up a document in the thinking.
>>>
>>>3. An archive, checksum() implementation that provides a view of any 
>>>changes is also preferrable since not all changes to previously signed 
>>>content may be deemed to invalidate a signature.  This concept of 
>>>legality and material vs. immaterial changes to a contract exists in 
>>>many legal jurisdictions.  For example, if you sign a contract then 
>>>later change your postal code, that is probably insufficient to 
>>>invalidate the entire contract.
>>>
>>>Duane
>>>
>>>Anders Rundgren wrote:
>>>
>>>    
>>>
>>>>Duane,
>>>>I may have been unclear but my intention was not alluding that there 
>>>>any major security issues hidden here. 
>>>> 
>>>>For a universal signature/document system like Adobe's, these terms 
>>>>may indeed be flawed (or not apply) as you say.  A web-only signature 
>>>>scheme may though be differently architected and in such schemes the 
>>>>terms Dry and Wet terms are not entirely wrong.
>>>>
>>>>My personal preference is that a possible standards effort should only 
>>>>target Dry signatures as these (in a web environment NB), are more 
>>>>flexible due to the separation of "user views" (static documents in 
>>>>arbitrary formats), signatures, and possible associated transaction data.
>>>>
>>>>*Secure Workflow*
>>>> 
>>>>A further complexity is that few organizations including the US 
>>>>federal agencies have yet begun to look on how secure messaging is to 
>>>>be accomplished on a wider scale except by using e-mail.
>>>> 
>>>>However, e-mail has huge limitations for sophisticated (automated and 
>>>>interactive) workflow compared to web based systems where the 
>>>>"transaction" and the "view", are typically not using a common 
>>>>representation.  The latter of course has a major impact on how 
>>>>signatures can be utilized.
>>>> 
>>>>I have personally "toyed" with a number of use cases in order to clear 
>>>>the picture for myself (to begin with...).  One simple but still 
>>>>pretty universal such use-case is the e-purchasing process where one 
>>>>or more employees are running an internal workflow system where a 
>>>>purchase request is, after proper authorization, converted into a 
>>>>purchase order and sent to a supplier. 
>>>> 
>>>>My own take on the aforementioned e-purchasing process and using the 
>>>>web is as follows:
>>>> 
>>>>1. The user is (when he considers him as ready), presented a completed 
>>>>requisition proposal in for example HTML or PDF, which he is requested 
>>>>to sign and submit.   In the background the actual data is usually 
>>>>held by the web server session in a "computer-friendly" format.
>>>> 
>>>>2. After signature validation etc by the workflow system. the 
>>>>requisition is archived together with the user's signature for 
>>>>possible /future references/
>>>> 
>>>>3. Assuming the user is the final authorizer, a purchase order is now 
>>>>created in a B2B-network specific format (like UBL or EDI), based on 
>>>>the requisition data (kept in the web session).
>>>> 
>>>>4.  The completed purchase order is then archived in a table linked to 
>>>>the signed requisition for possible /future references/.
>>>> 
>>>>5.  Finally, the purchase order is secured[*] and sent away for 
>>>>fulfillment in a B2B-network defined way
>>>> 
>>>>Steps 2-5 are automatically performed by the workflow system 
>>>>(server).  Except for user signatures,/ the scheme above is the 
>>>>de-facto standard way of performing B2B operations/.
>>>> 
>>>>regards
>>>>Anders Rundgren
>>>>Working for a major US computer security company but here acting as an 
>>>>individual
>>>> 
>>>>*]  This part is unfortunately a major problem for many people working 
>>>>with PKI as /it is really the workflow system that creates, secures, 
>>>>and sends purchase orders to external suppliers/.  Due to this, 
>>>>existing [/and widely used/] B2B schemes are almost exclusively 
>>>>non-secured or are using shared secrets as such schemes (/in spite of 
>>>>being completely inferior/) seem to pass without major consideration, 
>>>>while "signing PKI-servers", immediately brings in the legal 
>>>>department ("a machine has no will or legal power"), the security 
>>>>experts ("this is violating end-to-end security"), and forces most 
>>>>such efforts into a dead halt.  A maybe vane hope, is that these very 
>>>>interesting issues will be properly "aired" when/if a web signature 
>>>>standards process is launched.
>>>>
>>>>----- Original Message -----
>>>>From: "Duane Nickull" <dnickull@adobe.com <mailto:dnickull@adobe.com>>
>>>>Cc: "eGov OASIS" <egov@lists.oasis-open.org 
>>>><mailto:egov@lists.oasis-open.org>>
>>>>Sent: Thursday, August 25, 2005 19:41
>>>>Subject: Re: [egov] "Dry" and "Wet" signatures - A definition
>>>>
>>>>
>>>>Anders et al:
>>>>
>>>>I will suggest you may want to think about this differently.  Many
>>>>signature mechanisms work in a way that mitigate the problem you are
>>>>hinting at without having to make this distinction.  Attempting to make
>>>>two classes of signature for mutable vs. immutable content is flawed IMO
>>>>since you would have to fully understand every possible way a document
>>>>or content *might* be modified.  This is simply beyond the grasp of any
>>>>group of people since there are so many variables (metadata changes,
>>>>versions, file names etc.) plus you are relying on third party vendor
>>>>statements to be 100% accurate.
>>>>
>>>>A better methodology is to stipulate that at the time of signing, a hash
>>>>is made of the exact content using state of the art algorithms and if
>>>>the content later changes, the signature block is flagged to indicate
>>>>that there have been changes since it was signed and let the actor
>>>>decide how they want to proceed.  Adobe Acrobat's signature method works
>>>>this way.  If for any reason, any of it changes, the signature
>>>>presentation is flagged to indicate such.  This method was perfected by
>>>>Adobe, RSA, Entrust, VeriSign, GeoTrust, and ActivCard.  There is a lot
>>>>of information available on this from our website:
>>>>http://www.adobe.com/security/digsig.html
>>>>
>>>>The attached file was signed, then changed to demonstrate this.  If you
>>>>go to the signature field, you can click on the triangle symbol by the
>>>>green check mark.  It will open a dialog window that tells you the
>>>>document is still the same, but the values themselves have been altered
>>>>since (this is important to distinguish between).  If you select
>>>>"signature properties", you get even more information.
>>>>
>>>>Under the summary, the window will note any changes.  If you select the
>>>>"document" tab, a modification details window appears.  There is a
>>>>button that allows you to generate a change log to compute modifications
>>>>subsequent to signing the document.  You can also select 'View Signed
>>>>Version' to see the version that was signed and compare the two documents.
>>>>
>>>>I agree that mutability detection algorithms are complex.  Our mechanism
>>>>was the result of numerous companies collaborating with customers to
>>>>ensure all legal and technical problems were solved.  This was a
>>>>somewhat lengthly process.
>>>>
>>>>Best wishes.
>>>>
>>>>Duane
>>>>
>>>>Anders Rundgren wrote:
>>>>
>>>>      
>>>>
>>>>>Dear list,
>>>>>In a previous posting where I referred to some discussions concerning
>>>>>a possible Web Sign standards effort within OASIS, "Dry" and "Wet"
>>>>>signatures were mentioned.  Several off-list messages indicate that
>>>>>these terms need a proper explanation.
>>>>>
>>>>>This comes to no big surprise as these terms have actually been coined
>>>>>by myself in the absence of an established terminology in this
>>>>>actually rather virgin field.
>>>>>
>>>>>*"Wet" web-signatures
>>>>>*An editable document, be it an MS Word document or an HTML form with
>>>>>edit fields, radio buttons etc. is filled-in and signed by the user
>>>>>and then sent to the service provider.
>>>>>
>>>>>*"Dry" web-signatures*
>>>>>The user is (after an arbitrary interactive process with a service
>>>>>provider), presented, a static (read-only) document and is requested
>>>>>to sign it in order to indicate "acceptance".  Since the document
>>>>>actually comes from the service provider, the result sent to the
>>>>>service provider is typically only a detached signature of the shown
>>>>>document.
>>>>>
>>>>>*Further comments*
>>>>>These schemes represent two different schools, one which tries to
>>>>>mimic the existing paper form world, while the other scheme is more
>>>>>aligned with how the web is currently used.
>>>>>
>>>>>*Implications*
>>>>>Superficially these schemes may appear similar, but that is indeed not
>>>>>the case; there is probably a 10-to-1 difference in complexity unless
>>>>>you restrict "Wet" signatures to only support a single document
>>>>>format.  The reason for this increase in complexity is that each
>>>>>document format has its own native signature format (or has no defined
>>>>>signature format at all), as well as its own input data validation
>>>>>scheme.  Using "Dry" detached signatures, you can achieve the same
>>>>>thing as S/MIME does, namely document format independence with respect
>>>>>to the signature process (except for some trivial canonicalizations). 
>>>>>Possible input data validation is assumed to have been carried out in
>>>>>earlier phases of a web session, using standard web methodology. 
>>>>>There are numerous other implications as well concerning the use of
>>>>>"Wet" and "Dry" signatures, but these are far outside the range of an
>>>>>e-mail posting.
>>>>>
>>>>>Anders Rundgren
>>>>>Working for a major US computer security company but here acting as an
>>>>>individual
>>>>>        
>>>>>
>>>>--------------------------------------------------------------------------------
>>>>
>>>>
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