For documents, take a look at PDF/A (PDF for Archiving) it's a PDF subset for long-term preservation. It was just ratified by ISO. http://www.gcn.com/vol1_no1/daily-updates/25986-1.html
For PKI signatures, we've addressed what's probably their biggest long-term issue - which is what happens to a signed document when the signing certificates expire? For long-term signatures in PDF, we can capture the certificate revocation response at sign-time and embed it in the signed document. Certificate revocation servers (particularly OCSP) typically time-stamp their responses. By including this response within the signed document, you establish a) revocation status of the credential at sign-time, b) trusted time/date that this occurred from the server (we can also add RFC 3160 timestamps) c) authenticity of this information as it's contained within the signed document itself. This means the document can be validated in the absence of any external information and effectively creates an archivable signature.
Ed
--
John Messing wrote:
And there are long-term archival issues that still remain unresolved.-------- Original Message -------- Subject: Re: [egov] Re: Secure Workflow. Was: [egov] "Dry" and "Wet" signatures - A definition From: Duane Nickull <dnickull@adobe.com> Date: Mon, August 29, 2005 2:57 pm To: Anders Rundgren <anders.rundgren@telia.com> Cc: Ed Chase <chase@adobe.com>, eGov OASIS <egov@lists.oasis-open.org> 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-------------------------------------------------------------------------------- --------------------------------------------------------------------- To unsubscribe from this mail list, you must leave the OASIS TC that generates this mail. You may a link to this group and all your TCs in OASIS at: https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php--------------------------------------------------------------------- To unsubscribe from this mail list, you must leave the OASIS TC that generates this mail. 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