How do I create a self-signed certificate for code signing on Windows?

Asked 17/9, 2008 at 16:4 Answered 6/4, 2022 at 16:1

298

How do I create a self-signed certificate for code signing using the Windows SDK?

Grajeda answered 17/9, 2008 at 16:4 Comment(0)

419

Updated Answer

If you are using the following Windows versions or later: Windows Server 2012, Windows Server 2012 R2, or Windows 8.1 then MakeCert is now deprecated, and Microsoft recommends using the PowerShell Cmdlet New-SelfSignedCertificate.

If you're using an older version such as Windows 7, you'll need to stick with MakeCert or another solution. Some people suggest the Public Key Infrastructure Powershell (PSPKI) Module.

Original Answer

While you can create a self-signed code-signing certificate (SPC - Software Publisher Certificate) in one go, I prefer to do the following:

Creating a self-signed certificate authority (CA)

makecert -r -pe -n "CN=My CA" -ss CA -sr CurrentUser ^
         -a sha256 -cy authority -sky signature -sv MyCA.pvk MyCA.cer

(^ = allow batch command-line to wrap line)

This creates a self-signed (-r) certificate, with an exportable private key (-pe). It's named "My CA", and should be put in the CA store for the current user. We're using the SHA-256 algorithm. The key is meant for signing (-sky).

The private key should be stored in the MyCA.pvk file, and the certificate in the MyCA.cer file.

Importing the CA certificate

Because there's no point in having a CA certificate if you don't trust it, you'll need to import it into the Windows certificate store. You can use the Certificates MMC snapin, but from the command line:

certutil -user -addstore Root MyCA.cer

Creating a code-signing certificate (SPC)

makecert -pe -n "CN=My SPC" -a sha256 -cy end ^
         -sky signature ^
         -ic MyCA.cer -iv MyCA.pvk ^
         -sv MySPC.pvk MySPC.cer

It is pretty much the same as above, but we're providing an issuer key and certificate (the -ic and -iv switches).

We'll also want to convert the certificate and key into a PFX file:

pvk2pfx -pvk MySPC.pvk -spc MySPC.cer -pfx MySPC.pfx

If you are using a password please use the below

pvk2pfx -pvk MySPC.pvk -spc MySPC.cer -pfx MySPC.pfx -po fess

If you want to protect the PFX file, add the -po switch, otherwise PVK2PFX creates a PFX file with no passphrase.

Using the certificate for signing code

signtool sign /v /f MySPC.pfx ^
              /t http://timestamp.url MyExecutable.exe

(See why timestamps may matter)

If you import the PFX file into the certificate store (you can use PVKIMPRT or the MMC snapin), you can sign code as follows:

signtool sign /v /n "Me" /s SPC ^
              /t http://timestamp.url MyExecutable.exe

Some possible timestamp URLs for signtool /t are:

http://timestamp.verisign.com/scripts/timstamp.dll
http://timestamp.globalsign.com/scripts/timstamp.dll
http://timestamp.comodoca.com/authenticode
http://timestamp.digicert.com

Full Microsoft documentation

Downloads

For those who are not .NET developers, you will need a copy of the Windows SDK and .NET framework. A current link is available here: [SDK & .NET][5] (which installs makecert in `C:\Program Files\Microsoft SDKs\Windows\v7.1`). Your mileage may vary.

MakeCert is available from the Visual Studio Command Prompt. Visual Studio 2015 does have it, and it can be launched from the Start Menu in Windows 7 under "Developer Command Prompt for VS 2015" or "VS2015 x64 Native Tools Command Prompt" (probably all of them in the same folder).

Grajeda answered 14/10, 2008 at 14:3 Comment(19)

Is there any way to populate the certificate's email address field using this method? Right click exe>properties>digital signatures shows email as "not available" after signing. – Sideslip 17/5, 2012 at 10:52

If you get "too many parameters" errors then you check you didn't edit out one of the hyphens accidentally. Failing that - retype the hyphens - don't copy paste. – Olnek 14/8, 2012 at 0:8

@Sideslip To populate the email field of the certificate, simply add E=your@email. Eg: makecert -pe -n "CN=My SPC,E=email@domain" ........ – Hailee 2/2, 2013 at 11:41

Don't you need the Extended Use key flag -eku 1.3.6.1.5.5.7.3.3 so the cert can be used for code signing (I know powershell fails to sign scripts if it is missing it) – Thebault 20/2, 2013 at 23:2

Yes. Set-AuthenticodeSignature is much more picky about which certificates it will accept. It also requires separate CA and SPC certificates. – Grajeda 21/2, 2013 at 12:24

@Scott and Roger: Either of you know why Set-AuthenticodeSignature won't work with a self-signed (or issuer signed for that matter) certificate with 'All applications' and ' All purposes' in Certificate MMC? – Godman 13/7, 2013 at 5:24

@MikeCheel As to "why" only Microsoft can say. You may be better off asking on their forums for an answer. – Thebault 13/7, 2013 at 5:26

It's not necessary to get the Windows SDK to get these files. They are quite small and self contained so they can be downloaded individually. – Butanol 1/8, 2013 at 22:25

I noticed you commented that your example is good for "test/internal purposes" is this method acceptable for distribution? (Allowing enough people to click "run anyway" so windows can learn to trust your certificate?) – Rhyolite 10/3, 2014 at 7:58

@AdamPhelps, Windows won't "learn" to trust your certificate. Your users need to install the CA certificate in the Root store. This is, generally speaking, a bad idea (because root CA certificates can be used for nefarious purposes). It can make sense in an enterprise scenario, though. – Grajeda 10/3, 2014 at 8:11

@RogerLipscombe Thanks for the help. I read this bit from Microsoft about Smartscreen and code signing. I understood it to apply to self-signed code as well. So to clarify, this is only for Authenticode CAs? – Rhyolite 10/3, 2014 at 9:30

I think there's a typo, and that you may have switched the /n and /s flags in the last example. The first line should probably read: signtool sign /v /s Me /n SPC /d http://www.me.me ^, right? – Foetor 29/10, 2014 at 17:35

@OskarLindberg I guess that it's correct and not switched. The /n is used for the subject name and the /s is used for the store name according to the documentation – Amaleta 24/7, 2016 at 6:17

It's in the answer: "MakeCert is available from the Visual Studio Command Prompt" – Grajeda 28/11, 2016 at 18:54

I tried this method to avoid my .exe to be recognized as "This file might be dangerous" by antivirus software, but it didn't help. Should I use a paid CA provider instead? Any experience about this? – Diner 29/7, 2017 at 14:2

Hi @RogerLipscombe, I used this process to sign an XLL. All seems to be fine for the certificates, but Excel still won't accept the Add-In. I wrote a description here #47547887. Would you mind taking a look and seeing if you could spot something wrong? I'd be very grateful! – Tucky 29/11, 2017 at 7:41

Looks like the Windows 8 version of New-SelfSignedCertificate does not allow a -Type parameter. I cannot generate a code signing certificate with this :/ – Mosira 25/1, 2019 at 0:23

I tried on Windows10. All commands still work except for the signing using the pfx. I got SignTool Error: No certificates were found that met all the given criteria. – Fritzsche 27/2, 2020 at 9:5

I'm having big problems with the new and recommended New-SelfSignedCertificate with which I'm trying to clone an existing expired certificate using -CloneCert. It is documented to use the same key algorithm as the original certificate, instead it resets the algorithm to rsa1 from rsa256. – Heliozoan 30/11, 2020 at 16:16

113

As stated in the answer, in order to use a non deprecated way to sign your own script, one should use New-SelfSignedCertificate.

Generate the key:

New-SelfSignedCertificate -DnsName [email protected] -Type CodeSigning -CertStoreLocation cert:\CurrentUser\My

Export the certificate without the private key:

Export-Certificate -Cert (Get-ChildItem Cert:\CurrentUser\My -CodeSigningCert)[0] -FilePath code_signing.crt

The [0] will make this work for cases when you have more than one certificate... Obviously make the index match the certificate you want to use... or use a way to filtrate (by thumprint or issuer).

Import it as Trusted Publisher

Import-Certificate -FilePath .\code_signing.crt -Cert Cert:\CurrentUser\TrustedPublisher

Import it as a Root certificate authority.

Import-Certificate -FilePath .\code_signing.crt -Cert Cert:\CurrentUser\Root

Sign the script (assuming here it's named script.ps1, fix the path accordingly).

Set-AuthenticodeSignature .\script.ps1 -Certificate (Get-ChildItem Cert:\CurrentUser\My -CodeSigningCert)

Obviously once you have setup the key, you can simply sign any other scripts with it.
You can get more detailed information and some troubleshooting help in this article.

Picky answered 20/7, 2018 at 13:14 Comment(9)

Brilliant except for script.ps1 which comes out of nowhere even though it must be self-evident to everyone but me. Darn thing. I get the error File script.ps1 was not found and that's that. – Brion 4/12, 2019 at 4:49

@Lara thanks for the feedback I have added some contextual info to make it easier even when trying on low caffeine ;-) – Picky 5/12, 2019 at 13:27

@chammi, the quick reply is much appreciated. Though, for some reason, all I see now is empty gray rectangles. All the code is gone from the 'code' blocks. Just the gray background is shown. – Brion 6/12, 2019 at 19:53

@Lara thanks for signaling, I hadn't payed close attention while editing, It seems StackOverflow is now more picky about the syntax of the blocks and now requires a new line before the beginning of the code. – Picky 7/12, 2019 at 23:33

I was able to use this answer to sign a .exe that was compiled from python code. and windows SIGNTOOL shows verified, but when I share other users still get a windows defender pop up, any ideas? – Wennerholn 12/5, 2020 at 17:31

@Tyger, have you tried to give the other users the .crt and asked them to add it as trusted publisher as explained in step 3 ? – Picky 25/5, 2020 at 13:12

last command should also have a proper index : Set-AuthenticodeSignature ... -Certificate (Get-ChildItem Cert:\CurrentUser\My -CodeSigningCert)[1] – Pogonia 30/4, 2022 at 0:56

Well, that was a complete waste of time - "Your connection is not private" – Myself 3/2 at 17:19

Anyone struggling with the script.ps1... That is ONLY if you are signing a PowerShell script. Omit that command, as your certificate is already created in the current folder and ready to be used for your application. – Bane 20/2 at 19:26

It's fairly easy using the New-SelfSignedCertificate command in Powershell. Open powershell and run these 3 commands.

Create certificate:

$cert = New-SelfSignedCertificate -DnsName www.yourwebsite.com -Type CodeSigning -CertStoreLocation Cert:\CurrentUser\My

Set the password for it:

$CertPassword = ConvertTo-SecureString -String "my_passowrd" -Force -AsPlainText

Export it:

Export-PfxCertificate -Cert "cert:\CurrentUser\My\$($cert.Thumbprint)" -FilePath "d:\selfsigncert.pfx" -Password $CertPassword

Your certificate selfsigncert.pfx will be located @ D:/

Optional step: You would also require to add certificate password to system environment variables. do so by entering below in cmd:

setx CSC_KEY_PASSWORD "my_password"

Ataraxia answered 6/11, 2017 at 19:15 Comment(2)

JerryGoyal do you know how to convert a self signed certificate into a CA Root Trusted Certificate? – Proliferate 29/11, 2017 at 9:59

There was a typo in the last script. I should be

Export-PfxCertificate -Cert "cert:\CurrentUser\My\$($cert.Thumbprint)" -FilePath "d:\selfsigncert.pfx" -Password $CertPassword

– Begley 17/5, 2022 at 7:28

Roger's answer was very helpful.

I had a little trouble using it, though, and kept getting the red "Windows can't verify the publisher of this driver software" error dialog. The key was to install the test root certificate with

certutil -addstore Root Demo_CA.cer

which Roger's answer didn't quite cover.

Here is a batch file that worked for me (with my .inf file, not included). It shows how to do it all from start to finish, with no GUI tools at all (except for a few password prompts).

REM Demo of signing a printer driver with a self-signed test certificate.
REM Run as administrator (else devcon won't be able to try installing the driver)
REM Use a single 'x' as the password for all certificates for simplicity.

PATH %PATH%;"c:\Program Files\Microsoft SDKs\Windows\v7.1\Bin";"c:\Program Files\Microsoft SDKs\Windows\v7.0\Bin";c:\WinDDK\7600.16385.1\bin\selfsign;c:\WinDDK\7600.16385.1\Tools\devcon\amd64

makecert -r -pe -n "CN=Demo_CA" -ss CA -sr CurrentUser ^
   -a sha256 -cy authority -sky signature ^
   -sv Demo_CA.pvk Demo_CA.cer

makecert -pe -n "CN=Demo_SPC" -a sha256 -cy end ^
   -sky signature ^
   -ic Demo_CA.cer -iv Demo_CA.pvk ^
   -sv Demo_SPC.pvk Demo_SPC.cer

pvk2pfx -pvk Demo_SPC.pvk -spc Demo_SPC.cer ^
   -pfx Demo_SPC.pfx ^
   -po x

inf2cat /drv:driver /os:XP_X86,Vista_X64,Vista_X86,7_X64,7_X86 /v

signtool sign /d "description" /du "www.yoyodyne.com" ^
   /f Demo_SPC.pfx ^
   /p x ^
   /v driver\demoprinter.cat

certutil -addstore Root Demo_CA.cer

rem Needs administrator. If this command works, the driver is properly signed.
devcon install driver\demoprinter.inf LPTENUM\Yoyodyne_IndustriesDemoPrinter_F84F

rem Now uninstall the test driver and certificate.
devcon remove driver\demoprinter.inf LPTENUM\Yoyodyne_IndustriesDemoPrinter_F84F

certutil -delstore Root Demo_CA

Crusade answered 16/4, 2013 at 1:16 Comment(1)

If you want to use this for signing drivers, you need to import the CA certificate into the machine store. My example imports it into the user store, which is fine for most software, for test/internal purposes. – Grajeda 5/10, 2013 at 8:25

As of PowerShell 4.0 (Windows 8.1/Server 2012 R2) it is possible to make a certificate in Windows without makecert.exe.

The commands you need are New-SelfSignedCertificate and Export-PfxCertificate.

Instructions are in Creating Self Signed Certificates with PowerShell.

Electromechanical answered 28/2, 2016 at 16:12 Comment(1)

It's worth mentioning that, even if you install the WMF update to get PowerShell 4.0 on Windows 7, you won't have access to this command. It seems to be Win8 or Server 2012 or later. – Chisholm 19/4, 2016 at 21:48

You can generate one in Visual Studio 2019, in the project properties. In the Driver Signing section, the Test Certificate field has a drop-down. Generating a test certificate is one of the options. The certificate will be in a file with the 'cer' extension typically in the same output directory as your executable or driver.

Accelerate answered 12/10, 2021 at 1:23 Comment(0)

This post will only answer the "how to sign an EXE file if you have the crtificate" part:

To sign the exe file, I used MS "signtool.exe". For this you will need to download the bloated MS Windows SDK which has a whooping 1GB. FORTUNATELY, you don't have to install it. Just open the ISO and extract "Windows SDK Signing Tools-x86_en-us.msi". It has a merely 400 KB.

Then I built this tiny script file:

prompt $
echo off
cls

copy "my.exe" "my.bak.exe"

"c:\Program Files (x86)\Windows Kits\10\bin\10.0.22000.0\x64\signtool.exe" sign /fd SHA256 /f MyCertificate.pfx /p MyPassword My.exe

pause

Details

Natalyanataniel answered 6/4, 2022 at 16:1 Comment(0)

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