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

Security Problem Overview

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

Security Solutions

Solution 1 - Security

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 (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).

Solution 2 - Security

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@yourdomain.com -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.

Solution 3 - Security

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

> 1) Create certificate:
$cert = New-SelfSignedCertificate -DnsName www.yourwebsite.com > -Type CodeSigning -CertStoreLocation Cert:\CurrentUser\My > > 2) set the password for it:
$CertPassword = ConvertTo-SecureString > -String "my_passowrd" -Force -AsPlainText > > >3) Export it:
Export-PfxCertificate -Cert "cert:\CurrentUser\My$($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"

Solution 4 - Security

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

Solution 5 - Security

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.

Solution 6 - Security

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.

Solution 7 - Security

This post will only answer the "how to sing 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

Content Type	Original Author	Original Content on Stackoverflow
Question	Roger Lipscombe	View Question on Stackoverflow
Solution 1 - Security	Roger Lipscombe	View Answer on Stackoverflow
Solution 2 - Security	chaami	View Answer on Stackoverflow
Solution 3 - Security	GorvGoyl	View Answer on Stackoverflow
Solution 4 - Security	Dan Kegel	View Answer on Stackoverflow
Solution 5 - Security	Yishai	View Answer on Stackoverflow
Solution 6 - Security	trindflo	View Answer on Stackoverflow
Solution 7 - Security	Server Overflow	View Answer on Stackoverflow