* Jon Callas:
Nonrepudiation is a somewhat daft belief. Let me give a
gedankenexperiment. Suppose Alice phones up Bob and says, Hey, Bob,
I just noticed that you have a digital nature from me. Well, ummm, I
didn't do it. I have no idea how that could have happened, but it
wasn't me.
Jon Callas wrote:
Nonrepudiation is a somewhat daft belief. Let me give a
gedankenexperiment. Suppose Alice phones up Bob and says, Hey, Bob,
I just noticed that you have a digital nature from me. Well, ummm, I
didn't do it. I have no idea how that could have happened, but it
wasn't me.
Stefan Brands credentials [1] have an anti-lending feature where you have to
know all of the private components in order to make a signature with it.
My proposal related to what you said was to put a high value ecash coin as
one of the private components. Now they have a direct financial
On 22/12/11 18:17 PM, John Case wrote:
On Wed, 7 Dec 2011, Jon Callas wrote:
Nonrepudiation is a somewhat daft belief.
+1
Let me give a gedankenexperiment. Suppose Alice phones up Bob and
says, Hey, Bob, I just noticed that you have a digital nature from
me. Well, ummm, I didn't do it.
On 12/21/2011 04:24 PM, Michael Nelson wrote:
Somewhat related: The IEEE is asking for proposals to develop and
operate a CA as a part of their Taggant System. This involves
signing to validate the usage of packers (compressing executables).
Packers can make it hard for anti-virus programs to
, 2011 3:04 PM
Subject: Re: [cryptography] How are expired code-signing certs revoked?
On 12/21/2011 04:24 PM, Michael Nelson wrote:
Somewhat related: The IEEE is asking for proposals to develop and
operate a CA as a part of their Taggant System. This involves
signing to validate the usage
On 2011-12-07 16:31, Jon Callas wrote:
There are many things about code signing that I don't think I understand.
same here.
But I do understand something about the code creation, dissemination
and the trust between code creator and code user (primary parties),
and the role of the operating
On Dec 18, 2011, at 10:19 AM, M.R. wrote:
On 2011-12-07 16:31, Jon Callas wrote:
There are many things about code signing that I don't think I understand.
same here.
But I do understand something about the code creation, dissemination
and the trust between code creator and code user
On 8/12/11 02:11 AM, d...@geer.org wrote:
Another wrinkle, at least as a logic problem, would be
whether you can revoke the signing cert for a CRL and
what, exactly, would that mean -- particularly if the
last known good date is well astern and hence the
revocation would optimally be
On 10 Dec, 2011, at 11:58 PM, Peter Gutmann wrote:
Jon Callas j...@callas.org writes:
If someone actually built such combination of OS and marketplace, it would
work for the users very well, but developers would squawk about it. Properly
done, it could drop malware rates to close to nil.
Nico Williams n...@cryptonector.com writes:
On Fri, Dec 9, 2011 at 4:41 PM, Jeffrey Walton noloa...@gmail.com wrote:
Android also make the application a security principal for resource
sharing (its a smarter walled garden approach). Its an awesome
approach, especially when compared to Windows
On 9 Dec, 2011, at 9:15 PM, Peter Gutmann wrote:
Jon Callas j...@callas.org writes:
If it were hard to get signing certs, then we as a community of developers
would demonize the practice as having to get a license to code.
WHQL is a good analogy for the situations with certificates, it
Jon Callas j...@callas.org writes:
If someone actually built such combination of OS and marketplace, it would
work for the users very well, but developers would squawk about it. Properly
done, it could drop malware rates to close to nil.
Oh, developers would do more than squawk about it. Both
On 8 Dec, 2011, at 8:27 PM, Peter Gutmann wrote:
In any case getting signing certs really isn't hard at all. I once managed
it
in under a minute (knowing which Google search term to enter to find caches
of
Zeus stolen keys helps :-). That's as an outsider, if you're working inside
On Fri, Dec 09, 2011 at 01:01:05PM -0800, Jon Callas wrote:
If you have a certificate issue a revocation for itself, there is an obvious,
correct interpretation. That interpretation is what Michael Heyman said, and
what OpenPGP does. That certificate is revoked and any subordinate
On Dec 9, 2011, at 3:46 18PM, Jon Callas wrote:
On 8 Dec, 2011, at 8:27 PM, Peter Gutmann wrote:
In any case getting signing certs really isn't hard at all. I once managed
it
in under a minute (knowing which Google search term to enter to find caches
of
Zeus stolen keys helps :-).
On Fri, Dec 9, 2011 at 4:08 PM, Steven Bellovin s...@cs.columbia.edu wrote:
On Dec 9, 2011, at 3:46 18PM, Jon Callas wrote:
If it were hard to get signing certs, then we as a community of developers
would demonize the practice as having to get a license to code.
Peter is talking about stolen
From: Nico Williams n...@cryptonector.com
What should matter is that malware should not be able to gain control
of the device or other user/app data on that device, and, perhaps,
that the user not even get a chance to install said malware, not
because the malware's signatures don't chain up to a
On Fri, Dec 9, 2011 at 5:28 PM, Nico Williams n...@cryptonector.com wrote:
On Fri, Dec 9, 2011 at 4:08 PM, Steven Bellovin s...@cs.columbia.edu wrote:
On Dec 9, 2011, at 3:46 18PM, Jon Callas wrote:
If it were hard to get signing certs, then we as a community of developers
would demonize the
On Dec 9, 2011, at 5:41 04PM, Randall Webmail wrote:
From: Nico Williams n...@cryptonector.com
What should matter is that malware should not be able to gain control
of the device or other user/app data on that device, and, perhaps,
that the user not even get a chance to install said
On Fri, Dec 9, 2011 at 4:41 PM, Jeffrey Walton noloa...@gmail.com wrote:
This strengthens the argument for digital signatures as a means of
providing upgrade continuity and related application grouping /
isolation, as in the Android model. No need for a PKI then, no need
to pay for
On Fri, Dec 9, 2011 at 6:00 PM, Nico Williams n...@cryptonector.com wrote:
On Fri, Dec 9, 2011 at 4:41 PM, Jeffrey Walton noloa...@gmail.com wrote:
This strengthens the argument for digital signatures as a means of
providing upgrade continuity and related application grouping /
isolation, as
If the USG can't even keep thumb drives off of SIPR, isn't the
whole game doomed to failure? (What genius thought it would be
a good idea to put USB ports on SIPR-connected boxes, anyway?)
USG is, like all enterprises, struggling with consumerization
such as whether cloud services
Jon Callas j...@callas.org writes:
If it were hard to get signing certs, then we as a community of developers
would demonize the practice as having to get a license to code.
WHQL is a good analogy for the situations with certificates, it has to be made
inclusive enough that people aren't
On 12/07/11 14:42, William Whyte wrote:
Well, I think the theoretically correct answer is that you *should*...
these days all the installers can be available online, after all.
Except when the installer CD you need is the one for the network driver
on the new machine without which you can't
On 12/08/2011 09:16 AM, Darren J Moffat wrote:
On 12/07/11 14:42, William Whyte wrote:
Well, I think the theoretically correct answer is that you *should*...
these days all the installers can be available online, after all.
Except when the installer CD you need is the one for the network
2011/12/7 Marsh Ray ma...@extendedsubset.com:
On 12/07/2011 07:01 PM, lodewijk andré de la porte wrote:
I figured it'd be effective to create a security awareness group
figuring the most prominent (and only effective) way to show people
security is a priority is by placing a simple marking,
On Wed, Dec 7, 2011 at 4:32 PM, Peter Gutmann pgut...@cs.auckland.ac.nz wrote:
In the presence of such a [self-revoking] revocation [of a root certificate]
applications can react in one of three ways: they can accept the CRL
that revokes the certificate as valid and revoke it, they can reject
Peter Gutmann writes:
-+---
| This means that once a particular signed binary has been detected
| as being malware the virus scanner can extract the signing
| certificate and know that anything else that contains that
| particular certificate will also be malware, with the
d...@geer.org writes:
One would assume that the effort to get such a signing certificate would
persuade the bad team to use that cert for targeted attacks, not broadcast
ones, in which case you would be damned lucky to find it in a place where you
could then encapsulate it in a signature-based
: [cryptography] How are expired code-signing certs revoked?
Consider the following scenario:
1. Attackers steal a code-signing key and use it to sign malware.
2. The certificate for the stolen key expires.
3. Malware signed with the key turns up.
Since the signature is timestamped to allow it to still
@randombit.net; pgut...@cs.auckland.ac.nz;
wwh...@securityinnovation.com
Subject: RE: [cryptography] How are expired code-signing certs revoked?
William Whyte wwh...@securityinnovation.com writes:
I would say that you shouldn't *install* signed software after the
signing cert expires, but if you installed
Another wrinkle, at least as a logic problem, would be
whether you can revoke the signing cert for a CRL and
what, exactly, would that mean -- particularly if the
last known good date is well astern and hence the
revocation would optimally be retroactive.
--dan, quite possibly in a rat hole
There are many things about code signing that I don't think I understand.
I think that code-signing is a good thing, and that all things being equal,
code-signing is a good thing, and that code should be signed.
However, there seems to strange, mystical beliefs about it.
As an example, there's
On Dec 7, 2011, at 11:31 23AM, Jon Callas wrote:
But really, I think that code signing is a great thing, it's just being done
wrong because some people seem to think that spooky action at a distance
works with bits.
The question at hand is this: what is the meaning of expiration or
But really, I think that code signing is a great thing, it's just
being done
wrong because some people seem to think that spooky action at a distance
works with bits.
The question at hand is this: what is the meaning of expiration or
revocation
of a code-signing certificate? That I can't
On Dec 7, 2011, at 12:34 29PM, Jon Callas wrote:
On 7 Dec, 2011, at 8:52 AM, Steven Bellovin wrote:
On Dec 7, 2011, at 11:31 23AM, Jon Callas wrote:
But really, I think that code signing is a great thing, it's just being
done wrong because some people seem to think that spooky
d...@geer.org writes:
Another wrinkle, at least as a logic problem, would be whether you can revoke
the signing cert for a CRL and what, exactly, would that mean
That's actually a known problem (at least to PKI people). So what you're
really asking is whether a self-signed root cert can revoke
Marsh Ray ma...@extendedsubset.com writes:
Originally, public key systems were said to possess deliver this property of
'nonrepudiation', meaning a digital signature could effectively authenticate
the intent of the party associated with the private key.
Uhh, they were never said to deliver this
ianG i...@iang.org writes:
However, if one is relying on an external TTP to time-stamp the digital
signature, one can also rely on the TTP to evidence the hash of the document.
In which case, the digital signature is not performing any signing task
(although it may form a local authentication
Steven Bellovin s...@cs.columbia.edu writes:
Assume that there is some benefit to digitally-signed code.
There is at least one very obvious benefit: When malware is signed, it can't
mutate on each generation any more but has to remain static. This makes it
easier for the anti-malware folks to
[Really this is to the list, not so much Jon specifically]
On 12/07/2011 02:10 PM, Jon Callas wrote:
Let's figure out what we're trying to accomplish; after that, we
can try to figure out how to do it.
I think that's the central problem we're dealing with. There is scads
of mechanism and
On Dec 7, 2011, at 4:56 29PM, Peter Gutmann wrote:
Steven Bellovin s...@cs.columbia.edu writes:
Let's figure out what we're trying to accomplish; after that, we can try to
figure out how to do it.
See above, code signatures help increase the detecability of malware, although
in more or
On Dec 7, 2011, at 1:56 PM, Peter Gutmann wrote:
Steven Bellovin s...@cs.columbia.edu writes:
Assume that there is some benefit to digitally-signed code.
There is at least one very obvious benefit: When malware is signed, it can't
mutate on each generation any more but has to remain
On 7 Dec, 2011, at 11:34 AM, ianG wrote:
Right, but it's getting closer to the truth. Here is the missing link.
Revocation's purpose is one and only one thing: to backstop the liability to
the CA.
I understand what you're saying, but I don't agree.
CAs have always punted liability.
I'm afraid signing software is multiple levels of bullocks. Imagine a user
just clicking yes when something states Unsigned software, do you really
want to install?. Imagine someone working at either a software or a
signing company. Imagine someone owning a little bitty software company
that's
On 12/07/2011 07:01 PM, lodewijk andré de la porte wrote:
I figured it'd be effective to create a security awareness group
figuring the most prominent (and only effective) way to show people
security is a priority is by placing a simple marking, something like
this site isn't safe!
I thought
I'm afraid far more effective just doesn't cut it. Android has install
.APK from third party sources which you'll engage whenever you install an
APK without using the market, trusted or not. You can just put you malware
on the market though, they can then pull it back off 'n all but just
package
On 12/07/2011 08:12 PM, lodewijk andré de la porte wrote:
I'm afraid far more effective just doesn't cut it. Android has
install .APK from third party sources which you'll engage whenever you
install an APK without using the market, trusted or not.
That's why I didn't use Android as an
Marsh Ray ma...@extendedsubset.com writes:
Apple's iPhone app store code signing is far more effective for example.
The effectiveness of that isn't the PKI or the signing though, it's that Apple
vets the apps before allowing them in the store. You don't need certs, all you
need to do is have
On Wed, Dec 7, 2011 at 8:12 PM, lodewijk andré de la porte
lodewijka...@gmail.com wrote:
I'm afraid far more effective just doesn't cut it. Android has install
.APK from third party sources which you'll engage whenever you install an
APK without using the market, trusted or not. You can just
Marshall Clow mclow.li...@gmail.com writes:
This is only true if signing the malware is an expensive (in some terms)
proposition. It's certainly not expensive in terms of computing power.
The rate-limiting factor is how many certs you can steal, and how quickly. The
technology side doesn't
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