Subject: Re: [ers-02.txt] Questions

From: Denis Pinkas <[email-masked]>
Date: Thu, 12 May 2005 17:24:55 +0200

Tobias,

Surety has a lot of patents that involve the use of hashtrees used together 
with time-stamp tokens.

Do you have any idea if the realisations you have in mind will fall into 
these patents or outside ?

Denis

> Loïc,
> 
> Maybe to provide further info:
> 
> 
>>Well, it's more clear to me now...
>>ERS just proposes a syntax for EV that can be used by CSM to kepp
>>electronic signature valid.
>>But according to RFC-3126, ES-A is a format that reech the same target
>>than ERS in CMS.
> 
> 
> Yes. In some way ES-A in RFC3126 is trying to achieve the same. 
> With ES-A you can try to "re-sign" a signed file with a new layer wrapped around it every time a cryptographic algorithm gets weak (respectively before) - the concept is quite obvious and well thought for the use case to store only a limited number of signed documents. 
> 
> As Aleksej already described ERS also enables the possibility for long-term non repudiation and integrity. 
> Second aspect of ERS is that it scales for large volumes of signed documents. With ES-A you have to wrap around every file another layer. 
> With ERS you just create new hashtrees - which is if you think of e.g. about 10^6 to 10^9 documents a lot better concerning performance. (especially if only e.g. a public key algorithm gets weak or a used key length is no longer sufficient.)
> 
> Concerning RFC3126: From my opinion it is not necessary that ERS will obsolete ES-A. But I surely expect that many big storage, Document Management System and ECM vendors will implement ERS and not ES-A. So in B2B and B2C we will most probably seeing a lot of ERS.
> 
> The coexistence of ES-A and ERS will be something to discuss when ERS is finally an RFC.
> 
> Best regards
> 
> 	Tobias
> 
> 
> 
> 
> 
> 
>>So my question is, if i want to archive signature, i have the choice
>>between RFC3126 ES-A or ERS in CMS. Am I right ?
>>
>>If I am, will ES-A be obsoleted by ERS in CSM (as shown in Appendix A in
>>[ers-02])  ?
>>
>>But be sure that I understand ERS is more than just a way to maintain a
>>singature valid.
>>
>>Regards,
>>
>>Loïc
>>
>>
>>
>>
>>>-----Message d'origine-----
>>>De : A. Jerman Blazic [mailto:[email-masked]]
>>>Envoyé : vendredi 29 avril 2005 11:48
>>>À : HOUSSIER Loic RD-MAPS-ISS; [email-masked]
>>>Objet : RE: [ers-02.txt] Questions
>>>
>>>Loic
>>>
>>>This is what I didn't state. You have to distinguish the
>>>level of the two
>>>approaches. ERS deals mainly with providing syntax on (time)
>>>evidence and
>>>evidence on integrity of a data, while RFC3126 provides data
>>>strucutre for
>>>long term validity of a digital signatures. In this case RFC
>>>can rely on ERS
>>>for time and integrity evidence of a signature, so it is a
>>>more low level
>>>syntax. Or in other words, if you equip CMS with accredited
>>>time, you can
>>>ged basic ERS structure (of course ERS is more than that:
>>>e.g. grouping and
>>>hash trees). This is why I said the approaches of LTANS vs. XAdES are
>>>somehow different, while addressing similar problems.
>>>
>>>BR
>>>
>>>Aleksej
>>>
>>>
>>>>-----Original Message-----
>>>>From: HOUSSIER Loic RD-MAPS-ISS
>>>>[mailto:[email-masked]]
>>>>Sent: 29. april 2005 11:24
>>>>To: A. Jerman Blazic; [email-masked]
>>>>Subject: RE: [ers-02.txt] Questions
>>>>
>>>>Aleksej,
>>>>Thanks for your reply.
>>>>
>>>>So, to demonstrate the existantce and stability of signature
>>>>on particular, there will be two ways in PKIX community:
>>>>One using rfc3126, one with ERS attribute within a CMS
>>>>signature object. Am I wrong ?
>>>>
>>>>Loïc
>>>>
>>>>
>>>>
>>>>
>>>>>-----Message d'origine-----
>>>>>De : A. Jerman Blazic [mailto:[email-masked]] Envoyé :
>>>>
>>>>vendredi 29
>>>>
>>>>>avril 2005 11:08 À : HOUSSIER Loic RD-MAPS-ISS;
>>>>
>>>[email-masked]
>>>
>>>>>Objet : RE: [ers-02.txt] Questions
>>>>>
>>>>>Dear Loic
>>>>>
>>>>>I would be very careful here. XAdES for example is like the
>>>>
>>>>name says:
>>>>
>>>>>syntax for extended signature, which builds on top of a
>>>>
>>>>signature and
>>>>
>>>>>includes all needed complementary data to provide long term
>>>>
>>>>stability
>>>>
>>>>>of digital signatures. The LTANS position, as I understand it,
>>>>>distances from such approach and deals with long term
>>>>
>>>stability of
>>>
>>>>>data. ERS in this case defines requirements on how to
>>>>
>>>>demonstrate the
>>>>
>>>>>existence and stability of data (not signature on
>>>>
>>>particular) on a
>>>
>>>>>timeline. It does not define the data structure nor the
>>>>
>>>>syntax and at
>>>>
>>>>>the moment you can freely use any interpretation of an
>>>>
>>>>evidence record
>>>>
>>>>>including CMS. But XAdES? I am not so sure....
>>>>>
>>>>>Best regards
>>>>>
>>>>>Aleksej
>>>>>
>>>>>
>>>>>>-----Original Message-----
>>>>>>From: [email-masked]
>>>>>>[mailto:[email-masked]] On Behalf Of
>>>>>
>>>HOUSSIER Loic
>>>
>>>>>>RD-MAPS-ISS
>>>>>>Sent: 29. april 2005 10:46
>>>>>>To: [email-masked]
>>>>>>Subject: [ers-02.txt] Questions
>>>>>>
>>>>>>
>>>>>>Hi all,
>>>>>>
>>>>>>Reading ERS_02, I have question :
>>>>>>It s said that ER can be part of the Archive or can be
>>>>>
>>>stored as
>>>
>>>>>>another file. What I understand is that we can (using CMS
>>>>>
>>>>or XADES)
>>>>
>>>>>>do ER as part of the Archive.
>>>>>>But Is it compliant with ERS ?
>>>>>>
>>>>>>Thanks
>>>>>>
>>>>>>Loïc
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>-----Message d'origine-----
>>>>>>>De : [email-masked]
>>>>>>>[mailto:[email-masked]] De la part de
>>>>>>>[email-masked] Envoyé : vendredi 8 avril 2005
>>>>>>
>>>>21:29 À :
>>>>
>>>>>>>[email-masked] Cc : [email-masked] Objet : I-D
>>>>>>>ACTION:draft-ietf-ltans-ers-02.txt
>>>>>>>
>>>>>>>A New Internet-Draft is available from the on-line
>>>>>>
>>>>>Internet-Drafts
>>>>>
>>>>>>>directories.
>>>>>>>This draft is a work item of the Long-Term Archive and
>>>>>>
>>>>>>Notary Services
>>>>>>
>>>>>>>Working Group of the IETF.
>>>>>>>
>>>>>>>	Title		: Evidence Record Syntax (ERS)
>>>>>>>	Author(s)	: R. Brandner, et al.
>>>>>>>	Filename	: draft-ietf-ltans-ers-02.txt
>>>>>>>	Pages		: 25
>>>>>>>	Date		: 2005-4-8
>>>>>>>
>>>>>>>In many scenarios, users need to be able to ensure and
>>>>>>
>>>>prove the
>>>>
>>>>>>>   existence and integrity of data, especially digitally
>>>>>>
>>>>>>signed data,
>>>>>>
>>>>>>>in
>>>>>>>   a common and reproducible way over a long and possibly
>>>>>>
>>>>>>undetermined
>>>>>>
>>>>>>>   period of time.  This document specifies the syntax and
>>>>>>
>>>>>>processing
>>>>>>
>>>>>>>of
>>>>>>>   an Evidence Record, designed for long-term
>>>>>>
>>>>non-repudiation of
>>>>
>>>>>>>   existence of data, which particularly can be used for
>>>>>>
>>>>>>conservation
>>>>>>
>>>>>>>of
>>>>>>>   evidence of digitally signed data.
>>>>>>>
>>>>>>>A URL for this Internet-Draft is:
>>>>>>>
>>>>>>
>>>http://www.ietf.org/internet-drafts/draft-ietf-ltans-ers-02.txt
>>>
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> 
>