Digital Certificate

Digital Certificate "There are problems with the signature"

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Subject Author Date
Digital Certificate "There are problems with the signature" pretzel 09-05-2006
Posted by Paul Adare on September 7, 2006, 6:17 pm
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says...

> I have seen this also. For example SpamAssassin can have this affect (it
> adds a field in the header "X-Spam-Score". I would say any alteration of
> the email message would cause this error. Once you sign a message you can
> not change a single bit (it will fail the check).
>
> You hit upon a good point, I would guess that this is probably the
> culprit...
>

Your ignorance is showing, or are you just shooting in the dark? Perhaps
you should do some more research first. Modifying the header of a
message will not invalidate a signed email as only the message is signed
not the headers. If you'd take a moment to even begin to understand how
SMTP email works, you'd realize that every time an SMTP message goes
through an SMTP server, the headers change.

--
Paul Adare - MVP Virtual Machines
It all began with Adam. He was the first man to tell a joke--or a lie.
How lucky Adam was. He knew when he said a good thing, nobody had said
it before. Adam was not alone in the Garden of Eden, however, and does
not deserve all the credit; much is due to Eve, the first woman, and
Satan, the first consultant." - Mark Twain

Posted by =?Utf-8?B?UXVpZG51bmNTaW1jaGE= on September 6, 2006, 12:16 am
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Hello,

Forgive me for asking such a question....If "all" mail is "scanned",
wouldn't "all" mail be appendened?

or

If mail is scanned, then mail is appended with a "generic message"
...in the above case, it would seem that all mail would have a problem.

if mail is scanned and a filter only adds warning in specific cases
(keywords/characters), then some messages will be affected

Your filter may be "changing" the text and causing the problem

Sorry, I didn't help You a bit. I am nowhere near an expert, but you may
want to elaborate on the "all" and one/USERS area.




"pretzel" wrote:

> Dear All,
>
> We are testing out Digital Certificates as a prelude to Secure Messaging
> with some of our Clients.
>
> We obtained individual certificates for ourselves (as there is not many of
> us) but started our Client on a Business account with a CA.
>
> After setting up one of their users we notice that most times their email is
> fine, but other times instead of the usual "rosette" there is a red line and
> the statement "There are problems with the signature. Click the signature
> button for details."
>
> The message in the Security Properties is "Error: The message contents may
> 15:05:47 16/08/2006."
>
> As we use an external mail filter (so all our mail is scanned in transit) we
> believe that the scanning by our mail filter is causing the Digital
> Certificate to detect a modification (or attempt) and hence the error.
>
> My questions are:
>
> 1) Is the above assumption correct, and this is normal?
>
> 2) Is there anything that can be done to elimiate this (if caused by an
> external mail scanner perhaps not)
>
> 3)If we move to Secure Messaging where the email is encrypted and hence
> cannot be scanned by our mail filter, should I presume that the above error
> will not appear and that all will be OK (at least as much as it should be)?
>
> thanks
>
> -----
> pbw

Posted by Jeff B. on September 7, 2006, 10:26 am
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>From my experience, mail scanners (usually virus scanners - sometimes
content scanners) often only read the outgoing message. Others, append
every message with text that inidicates to the recipient that the
message has been scanned and "approved" as virus free by the scanner
(to give you a warm and fuzzy secure feeling).

For example, NOD32 appends body text as follows:

"
__________ NOD32 1.1742 (20060906) Information __________

This message was checked by NOD32 antivirus system.
http://www.eset.com
"

The above text was copied from a message I recieved from my wife's work
mail scanner.
However, I am using Norton AV2006. Norton scans my incoming and
outgoing messages, but does not append or alter any content (to my
knowledge).
If Norton finds a virus, it hijacks the message and quarantines it and
opens a windows dialogue box indicating so.

But, I don't know digitally signed messages or encrypted messages
respond to scanners trying to append them. I am trying to test that
out now...



QuidnuncSimcha wrote:
> Hello,
>
> Forgive me for asking such a question....If "all" mail is "scanned",
> wouldn't "all" mail be appendened?
>
> or
>
> If mail is scanned, then mail is appended with a "generic message"
> ...in the above case, it would seem that all mail would have a problem.
>
> if mail is scanned and a filter only adds warning in specific cases
> (keywords/characters), then some messages will be affected
>
> Your filter may be "changing" the text and causing the problem
>
> Sorry, I didn't help You a bit. I am nowhere near an expert, but you may
> want to elaborate on the "all" and one/USERS area.
>
>
>
>
> "pretzel" wrote:
>
> > Dear All,
> >
> > We are testing out Digital Certificates as a prelude to Secure Messaging
> > with some of our Clients.
> >
> > We obtained individual certificates for ourselves (as there is not many of
> > us) but started our Client on a Business account with a CA.
> >
> > After setting up one of their users we notice that most times their email is
> > fine, but other times instead of the usual "rosette" there is a red line and
> > the statement "There are problems with the signature. Click the signature
> > button for details."
> >
> > The message in the Security Properties is "Error: The message contents may
> > 15:05:47 16/08/2006."
> >
> > As we use an external mail filter (so all our mail is scanned in transit) we
> > believe that the scanning by our mail filter is causing the Digital
> > Certificate to detect a modification (or attempt) and hence the error.
> >
> > My questions are:
> >
> > 1) Is the above assumption correct, and this is normal?
> >
> > 2) Is there anything that can be done to elimiate this (if caused by an
> > external mail scanner perhaps not)
> >
> > 3)If we move to Secure Messaging where the email is encrypted and hence
> > cannot be scanned by our mail filter, should I presume that the above error
> > will not appear and that all will be OK (at least as much as it should be)?
> >
> > thanks
> >
> > -----
> > pbw


Posted by Jeff B. on September 8, 2006, 11:18 am
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I can't come up with any clear answer on this question. Limited
testing with the my wife's work mail scanner revealed that their mail
scanner appends all unsigned/unencrypted "incoming" mail "body text"
with the NOD32 signature.
But, when I send a signed or encrypted message, those messages do - not
- get appended with the NOD32 signature. Thus, they apparently do not
get altered and there are no errors encountered.
But this is a very limited test and I expect many different scanners
deal with signed/encrypted messages differently.

To the original poster of this thread:

- Find out who the 3rd party scanner is.
- Talk to their scanner administrator about the possibility their
scanner is corrupting message content because of altered message
content or appended text.
- Try finding another scanner service who will work with you on solving
the problem

It would be interesting to hear from someone who has real experience
with this issue...



Jeff B. wrote:
> >From my experience, mail scanners (usually virus scanners - sometimes
> content scanners) often only read the outgoing message. Others, append
> every message with text that inidicates to the recipient that the
> message has been scanned and "approved" as virus free by the scanner
> (to give you a warm and fuzzy secure feeling).
>
> For example, NOD32 appends body text as follows:
>
> "
> __________ NOD32 1.1742 (20060906) Information __________
>
> This message was checked by NOD32 antivirus system.
> http://www.eset.com
> "
>
> The above text was copied from a message I recieved from my wife's work
> mail scanner.
> However, I am using Norton AV2006. Norton scans my incoming and
> outgoing messages, but does not append or alter any content (to my
> knowledge).
> If Norton finds a virus, it hijacks the message and quarantines it and
> opens a windows dialogue box indicating so.
>
> But, I don't know digitally signed messages or encrypted messages
> respond to scanners trying to append them. I am trying to test that
> out now...
>
>
>
> QuidnuncSimcha wrote:
> > Hello,
> >
> > Forgive me for asking such a question....If "all" mail is "scanned",
> > wouldn't "all" mail be appendened?
> >
> > or
> >
> > If mail is scanned, then mail is appended with a "generic message"
> > ...in the above case, it would seem that all mail would have a problem.
> >
> > if mail is scanned and a filter only adds warning in specific cases
> > (keywords/characters), then some messages will be affected
> >
> > Your filter may be "changing" the text and causing the problem
> >
> > Sorry, I didn't help You a bit. I am nowhere near an expert, but you may
> > want to elaborate on the "all" and one/USERS area.
> >
> >
> >
> >
> > "pretzel" wrote:
> >
> > > Dear All,
> > >
> > > We are testing out Digital Certificates as a prelude to Secure Messaging
> > > with some of our Clients.
> > >
> > > We obtained individual certificates for ourselves (as there is not many of
> > > us) but started our Client on a Business account with a CA.
> > >
> > > After setting up one of their users we notice that most times their email
is
> > > fine, but other times instead of the usual "rosette" there is a red line
and
> > > the statement "There are problems with the signature. Click the signature
> > > button for details."
> > >
> > > The message in the Security Properties is "Error: The message contents may
> > > 15:05:47 16/08/2006."
> > >
> > > As we use an external mail filter (so all our mail is scanned in transit)
we
> > > believe that the scanning by our mail filter is causing the Digital
> > > Certificate to detect a modification (or attempt) and hence the error.
> > >
> > > My questions are:
> > >
> > > 1) Is the above assumption correct, and this is normal?
> > >
> > > 2) Is there anything that can be done to elimiate this (if caused by an
> > > external mail scanner perhaps not)
> > >
> > > 3)If we move to Secure Messaging where the email is encrypted and hence
> > > cannot be scanned by our mail filter, should I presume that the above error
> > > will not appear and that all will be OK (at least as much as it should
be)?
> > >
> > > thanks
> > >
> > > -----
> > > pbw


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