Issue 60875

Summary: Certificate key usage is not handled by the OpenOffice programs when sign a document digitaly
Product: General Reporter: vargaviktor <viktor.varga>
Component: codeAssignee: AOO issues mailing list <issues>
Status: ACCEPTED --- QA Contact:
Severity: Trivial    
Priority: P3 CC: issues
Version: OOo 2.0.1Keywords: security
Target Milestone: ---   
Hardware: All   
OS: All   
Issue Type: DEFECT Latest Confirmation in: ---
Developer Difficulty: ---

Description vargaviktor 2006-01-20 12:28:19 UTC
The cerficate key usage is not handled in the Digital Sign feature, so it is
possible, to sign a document with an encryption certificate.

1. Sign a document with an encryption certificate, (Key Enchipherment set)
2. It will be successful, so it is wrong.

By the regarding RFCs and ETSIs, the Non-Repudation bit and/or Digital Sign bit
should be set, for the signing certificate. Key Enchipherment should not
allowed, or minimum should together with a Digital Sign.

For qualified certs (EU):
only Non-Repudation
more info: 
RFC 3039

For other certificates: Non-Repudation and/or Digital Sign (
more info:
ETSI TS 102 280 
chapter 5.4.3 Key usage, table, Line A, B, C
(the RFC overides the description of qualified, so only the A usable in qulified)
Line D - not recommended, dread later
Line E - for encryption

D line - not recommended, because:
1) most of the EU contry laws are not allowing to use for digital signing a
combined certificate.
2) ETSI security notes describes, for security reasons it is not recommended.
Comment 1 thorsten.martens 2006-01-27 13:24:43 UTC
TM->FST: Please have a look, thanks !
Comment 2 frank 2006-01-27 14:04:04 UTC
Hi Joachim,

please have a look at this one.

Comment 3 kai.sommerfeld 2006-02-14 14:59:33 UTC
Comment 4 joachim.lingner 2006-03-21 16:15:22 UTC
Comment 5 kai.sommerfeld 2006-06-15 15:37:13 UTC
Comment 6 joachim.lingner 2007-12-07 16:01:02 UTC
Retargeting to 3.x
Comment 7 vargaviktor 2008-11-10 16:22:47 UTC
Tested on OO 3 and still not working.

Retargeting to OO4??? :)
Comment 8 joachim.lingner 2008-11-11 15:45:38 UTC
This issue will probably be retargeted. In my opinion the current implementation
is barely usable for a couple of reasons. What we need are requirements of the
form: "The signature must comply with standard A in order to be legally accepted
in country B." 

Because this is actually a huge task, i suggest that signature components may be
developed by individual parties and OOo is improved to better integrate these
components. Have a look at my OOo 2008 conference presentation:

Comment 9 vargaviktor 2008-11-11 16:28:06 UTC
My opinion, to filter out the signer certificates with Key Enchipherment Key Usage.

The separation of the encryption(EC), authentication(DS), and signing(NR)
function came from a security problem.

Please imagine it:

case 1: You have a certificate with DS, NR, EC.
You want to login on a webpage, and the server drops some random data to sign it.
You sign it, then the server check the signature, and logins you, when it is
correct. But if the server drops some patched data, not random, the server owner
will have a signed document, which is signed with a certificate, where the
allowed purposes includes non repudation (NR), so your "random data" was SIGNED
for them.

case 2: You have EC with NR bits.
You can have an application, which simply sign with your encription certificate,
of course, this is not a way, yo want, but you sign something, with a law
acceptable certificate.

case 3: You sing something with a EC certificate
You signed it, because you want to make it an official document. But when you
will use it, on the judge, you will found, oops, no really signeture on it. So
you lost on the judge.
Comment 10 joachim.lingner 2008-11-12 09:01:28 UTC
I agree that we should follow some standards here. If I remember correctly, the
German Signature Act requires the use of the right key usage as well. 

Your #1 scenario could maybe apply for the case when OOo establishes a https
connection and the server requires a client authentication. However, I am not
sure if this is possible at all with OOo.
Comment 11 vargaviktor 2008-11-12 14:51:29 UTC
Yes, jl, you have right.

I simply detailed the knowledge behind the separation of the certificates.