Signing Certificate - probable issue

[glawrence]

I have just read Termination of the certificates business of Startcom - Google Groups and I think we sign with a StartCom certificate, so maybe we need to look at other options?

[justinclift]

Thanks @glawrence. Yep, that will affect us.

The StartCom Certificate we use for signing is valid through to 2018-08-24, so we should be good until around then. We'll want to have our current release at the time be signed by some other cert provider, so we'll probably need to arrange something by June or July next year.

[dori4n]

The next best option is probably going to be Certum for you, they have an open source "deal" at EUR 29/year.

[justinclift]

Thanks @NightmareJoker2. We looked at Certum last time around too, but we need a certificate that is Microsoft Authenticode compatible. That page has no mention of Authenticode anywhere. 😦

If it did, we probably would have chosen them last time instead of going with StartCom. 😄

[justinclift]

As a data point, Centum's page for their "Standard Code Signing" product clearly mentions Authenticode compliance:

    https://www.certum.eu/certum/cert,offer_en_standard_code_signing.xml

If their Open Source one was, it be mentioned. 😄

[justinclift]

I've just emailed them directly to ask. It could be the case that their page just doesn't list it due to an oversight or something. 😄

[dori4n]

There are no special Authenticode™ certificates. It is merely a name for the system Windows uses to verify code signatures. If a certificate is signed by or valid descendant signers of any trusted root authority certificate in the trust store, and bears the code signing flag, it can be used to sign code, with, or without a timestamp (which requires a timestamp provider). This includes device drivers (not that this is required here). You can even add your own certification authority and it will work.

You can read more about this here:

1. Get a code signing certificate
2. Signing and Checking Code with Authenticode
3. Everything you need to know about Authenticode Code Signing

Advertising Authenticode™ support typically means whether a certification authority provides a timestamp provider (which is very misleading, to be sure), though you can use as many of those as you want and pick from any of them when you do. Signing with a timestamp is recommended, so the signature can remain valid, even after the signing certificate has expired.

[justinclift]

Thanks @NightmareJoker2, those URLs look to be pretty much exactly what we'll need. I remember having a bad time trying to figure out how to get things done last time around, and those look to be the exactly correct bits. 😄

With the Certum certificates, they've also responded saying the Open Source ones are Authenticode compatible anyway. So it indeed looks like Certum will be the ones chosen. 😄

[justinclift]

@NightmareJoker2 Looking at this again, as the current certificate expires in a few months + we're getting near to our next release.

With the Centum one's, I'm still finding it a bit confusing. Looking at their comparison chart, "Code and application signing for Windows 32 and 64 systems" seems like it's only part of their EV Code Signing option:

Even the "Eliminates system messages like 'Unknown publisher' and 'Unknown software'" doesn't seem to be something their Open Source Code signing cert does.

Very much confused now. 👼

[justinclift]

Pricing wise, the options seem to look like this:

Certum: https://en.sklep.certum.pl/data-safety/code-signing-certificates.html

• The MS page makes it look like the Certum ones are only useful for HW developers. It's very unclear. ☹️
• When looking at pricing, make sure to change the slider to "I do not have reader and cryptographic card", so they include one in the price.
• "Open Source" code signing (may be useless?): €86.00
• Standard code signing cert: €169.00
• EV code signing cert: €389.00

Comodo: https://www.instantssl.com/ssl-certificate-products/code-signing-index.html

• Comodo code signing cert: £166.95
• EV code signing cert: £299.00

DigiCert: https://www.digicert.com/order/order-1.php

• Standard code signing cert: $111.00 USD
• EV code signing cert: $224.00 USD

Entrust: https://www.entrustdatacard.com/products/digital-signing-certificates/code-signing-certificates

• "OV" (standard?) code signing cert: $299 USD
• EV code signing cert: $399 USD

GlobalSign: https://www.globalsign.com/en/code-signing-certificate/

• Standard code signing cert: $289 USD
• EV code signing cert: $410 USD

Symantec

• Doesn't give pricing without providing identifying details. They have an extremely bad reputation anyway, so they're not really a consideration.

[assarbad]

Hi there, just wanted to chime in. @glawrence is right, the issue already exists even before 2018-08-24 (as if it matters now, just two weeks out 😁 ). The problem is that if the CA has the trust withdrawn (or rather revoked) that automatically invalidates your signatures, because the signature relies on the validity of both the signer's certificate and the CA's certificate. It's all quite confusing and if you got the time I recommend reading this article.

Now your case doesn't require an EV certificate, but a simple class 3 certificate. Certum gives you that if you apply for their "Open Source" certificates and you qualify. Trust me on that one, I got one. Downside is that for the first time you need to purchase a USB-token which contains a smartcard which contains the key used for performing the CSR (certificate signing request), which you do after you have purchased the token. The certificate itself costs approx. 30.00 €. The reader and delivery is the expensive part the first time around.

In fact the only thing EV gives you is greater assurance that the owner of the certificate really is who s/he claims to be. On the technical end the only difference is that it's rooted in a different CA certificate, which is given a different level of trust by browsers (SSL) or operating systems (Authenticode).

Let's take it one by one. I'll go with Certum, because I know it works as I have one of their Open Source certificates for two of my open source projects (WinDirStat and ntobjx).

Certum: https://en.sklep.certum.pl/data-safety/code-signing-certificates.html

• The MS page makes it look like the Certum ones are only useful for HW developers. It's very unclear. ☹️

Well, if you are - like I am - a Windows kernel mode driver writer, it's not all that unclear. This article happens to be not for you 😁 ... seriously. As driver writers we have to consider a whole bunch of different rules, not the least of which is called the Kernel Mode Signing Policy. And then it also depends on how you install your driver. For example you can get away without EV certificate if you installed it in certain ways on certain older Windows versions (up until before Windows 10, IIRC). Besides, other rules exist for driver writers when it comes to dual-signing. Turns out that SHA1 is perfectly fine still as of now and even for Windows 10.

In short: don't trust the Microsoft documentation on signing too much. It's often outdated (and unclear what's outdated and what's not) it's often written in an unclear fashion and there have been - over the years - quite a number of contradicting statements across the various documentations sites.

• When looking at pricing, make sure to change the slider to "I do not have reader and cryptographic card", so they include one in the price.

That's an important one. You need that reader and card from them (i.e. Certum) to get and use their signing certificates.

• "Open Source" code signing (may be useless?): €86.00

Nope, works perfectly fine. That's a certificate rooted in a CA certificate with a SHA-2 (256-bit) hash and it's perfectly legit for your use case. You can even use it to dual-sign, although in this case the two signatures are not rooted in a certificate chain with one hashing algorithm each (like if you had two distinct certificates).

Keep in mind that some entities cannot be dual-signed. Among them, as of this writing (and to my knowledge) CAB files and MSI files.

• Standard code signing cert: €169.00

Standard class 3 code-signing certificate.

• EV code signing cert: €389.00

Class 3 code-signing certificate rooted in a special CA root certificate and therefore gaining a different trust in the environment in which the signed entity "runs".

Oh, one last remark. When working with signtool make sure you either have only a single copy on your system or only a single copy in your %PATH%. It's important because newer signtool binaries can get confused by older DLLs in the path and such. This leads to some very weird inexplicable errors or silent (without verbosity) failures which are easy to resolved once you know this.

Hope this helps,

Oliver

PS: Symantec sold its signing business to DigiCert

[assarbad]

Oh, one more thing. I think the Code and application signing for Windows 32 and 64 systems refers to Windows Store applications. Possibly in particular to the app packages (.appx etc) rather than the binaries.

[justinclift]

Thanks @assarbad, that does help. 😄

[tlhackque]

Welcome to the exciting world of X.509. Perhaps a few additional comments will help.

The sale and subsequent death of Startcom is unfortunate. Their business model (pay for validation, not for certificates) was ideal for individuals & open source projects.

The requirement for a hardware token is not (directly) due to certum - it's due to the requirements established by the CA Security Council in this document

See section 16.3, which requires that a code signing certificate's private key be stored on a hardware TPM. It doesn't have to be certum's - though certum may have specific requirements.

Symantec/DigiCert discontinued issuance of code signing certs for individuals. I assume the hassle wasn't worth it - as for a while, the malware crowd would buy certificates so their "product" would be easier to install.

Both Startcom and Symantic got in trouble for not following the CA rules on certificate issuance - the browser vendors essentially put them out of business by removing their root certificates from the official trust stores.

The hassle/expense factor is now high enough that I use a certificate from my own private CA. You can probably get away with that for your nightly builds (a simple self-signed is easier). Probably not for your releases.

EV is window dressing - expensive. And can NOT be issued to individuals - you have to be a government or government-recognized business entity. See this link The requirements are generally more stringent than Organization Validation (OV). Besides a different root CA, a CA certificate has a OID embedded in it that identifies it as (claiming to be) EV.

Organization validation requires an organization - many open source projects have a registered non-profit entity that makes that doable. Projects that don't (e.g. an informal group of developers) fall into the cracks between "individual" (and can't get cert) and "business" (costs and hassle of forming one). Some CAs might accept a DBA (Doing business as) certificate from your local city/town - they tend to be cheap, and don't require an attorney or lawyer. But they may not be accepted by all CAs (Startcom didn't accept them even for OV).

Informally, certum seems to be the choice of small open source projects. As noted above, they seem to be willing to validate individuals if there's enough evidence on the web that they are affiliated with a project. I have no personal experience with them, however.