A Mutable Log

A blog by Devendra Tewari

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Self-signed code signing certificates

Some setup and application executables need to be signed so that they are not flagged as a security risk by security software on Windows. Especially those that have virus-like behavior such as embedded executable resources that are extracted, and executed.

The following steps were performed on Windows, from the Developer Command Prompt installed by Visual Studio.

To generate self-signed certificate for code signing, run

makecert.exe -n CN=Test.org(Test) -r -h 0 -eku "1.3.6.1.5.5.7.3.3,1.3.6.1.4.1.311.10.3.13" -e 12/31/2017 -pe -sv Test.pvk Test.cer

Here’s a brief overview of the command line -n subject name -r create self-signed certificate -h max height of tree below this cert -eku comma separated enhanced key usage ids -e expiration date -pe private key is exportable -sv private key file name

You may specify a password or leave it empty.

To convert self-signed certificate to PFX format for usage with SignTool, run

Pvk2Pfx -pvk Test.pvk -spc Test.cer -pfx Test.pfx

To use SignTool to sign an executable, run

SignTool sign /fd SHA256 /a /f Test.pfx filepath.exe

Install certificate (Test.cer) to local machine before running executable.

Signing a Wix Toolset setup bundle

You cannot just sign the setup bundle executable and get it to work, because the embedded executable (engine.exe) remains unsigned and will be flagged as a security risk. Use the following steps to prepare setup bundle for installation without being flagged as a security risk.

First, detach the engine from setup as follows

insignia -ib setup.exe -o engine.exe

Sign engine.exe with your certificate using SignTool

SignTool sign /fd SHA256 /a /f Test.pfx engine.exe

Re-attach the signed engine.exe to the bundle

insignia -ab engine.exe setup.exe -o setup.exe

Sign setup.exe with your certificate

SignTool sign /fd SHA256 /a /f Test.pfx setup.exe