[cryptography] How are expired code-signing certs revoked?

Jeffrey Walton noloader at gmail.com
Fri Dec 9 17:41:23 EST 2011


On Fri, Dec 9, 2011 at 5:28 PM, Nico Williams <nico at cryptonector.com> wrote:
> On Fri, Dec 9, 2011 at 4:08 PM, Steven Bellovin <smb at 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 certs, which for most parts of the development
>> community aren't a prerequisite...  But there's an interesting dilemma here
>> if we insist on all code being signed.
>>
>> Assume that a code-signing cert costs {$,€,£,zorkmid}10000/year.  Everyone but
>> large companies would scream.  Now assume the cost is {$,€,£,zorkmid}.01/year
>> or even free.  At that price, it's a nuisance factor, and would be issued via
>> a simple web interface.  Simple web interfaces are scriptable (and we all know
>> the limits of captchas), which means that malware could include a "get a cert"
>> routine for the next, mutated generation of itself.  In fact, they're largely
>> price-insensitive, since they'd be programmed with a stash of stolen credit
>> cards....
>
> 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 certificates.
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 and *nix where sharing
is generally based upon a login context and enforced through DACLs.

> In the Android model it shouldn't matter that malware might be signed.
>  What should matter is that malware should not be able to gain control
> of the device or other user/app data on that device,
Right.

> that the user not even get a chance to install said malware, not
> because the malware's signatures don't chain up to a trusted CA but
> because the "app store" doesn't publish it and the user uses only
> trusted app stores.  Neither of the last two is easy to ensure though
It never hurts to wish.

Jeff



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