Slightly OT - i need the proper wording for a signed document

[Dirk Gottschalk]

Hi guys.

Am Freitag, den 02.11.2018, 12:53 +0100 schrieb Stefan Claas:
> On Fri, 2 Nov 2018 12:20:43 +0100, Wiktor Kwapisiewicz wrote:
> > On 02.11.2018 10:53, Stefan Claas wrote:
> > > Simply one can use a time stamping service, based on blockchain
> > > technology. I can then time stamp the .pdf. and put also a
> > > statement in the .pdf that the file is timestamped and don't must
> > > worry in the future if one MITM would try (and why?) to alter my
> > > documents.  
> > 
> > PDFs can be also timestamped when signing with standard RFC 3161
> > [0]
> > timestamping service.
> > 
> > Here's one example:
> > 
> > https://support.globalsign.com/customer/en/portal/articles/2361790-add-timestamp-server---adobe-acrobat
> > 
> > But there are numerous free RFC 3161 timestamping services.
> > 
> > Of course that's not the same as blockchain, but it's already
> > supported by numerous tools (like Adobe Acrobat).
> > [0]: https://tools.ietf.org/html/rfc3161
> 
> Hi Wiktor,
> 
> thanks a lot! Now this is awesome... i just timestamped my already
> signed .pdf with Adobe Reader DC and this does not invalidate my
> qualified signature, when saving the document again! :-) I must admit
> i did  not know this.

freetsa offers a free timestamping service based on blockchain
technology, AFAIK. I use it myself to stamp PDFs. The free service
offers 10 timestamps per day what should be enough for normal usage.

Regards,
Dirk

-- 
Dirk Gottschalk
Paulusstrasse 6-8
52064 Aachen, Germany

GPG: DDCB AF8E 0132 AA54 20AB  B864 4081 0B18 1ED8 E838
Keybase.io: https://keybase.io/dgottschalk
GitHub: https://github.com/Dirk1980ac

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: This is a digitally signed message part
URL: <https://lists.gnupg.org/pipermail/gnupg-users/attachments/20181102/78e29c92/attachment.sig>