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# Windows

## Overview

While Windows does not require applications to be code signed, doing so can help ensure the authenticity and integrity of your application when a user is trying to install it. This includes preventing Windows from showing warnings to users that your application is untrusted and may be dangerous.

To code sign your application with Briefcase, you must obtain a code signing certificate from a Certificate Authority (CA) and install it in a Windows certificate store.

## Obtain a Certificate

Microsoft manages a collection of Certificate Authorities that are trusted by default in Windows. A code signing certificate from any of these included entities should be trusted by a modern Windows machine.

Of note, a certificate for code signing is different from a certificate for other cryptographic purposes. For instance, a certificate used by a website to create encrypted HTTP connections cannot be used for code signing. Therefore, a request for a code signing certificate must specifically be for code signing. Certificate Authorities offering these services will make this clear during the request process.

Additionally, it is possible to create a code signing certificate directly within Windows. However, when you create a certificate yourself, it will likely be considered “self-signed”. Using such a certificate to code sign an application will not imbue it with the trust that a certificate from a Certificate Authority provides. Therefore, a self-signed certificate should not be used to code sign applications for distribution.

## Install the Certificate

Once a code signing certificate is requested, Certificate Authorities may vary is how the certificate is actually delivered to you. In general, though, you’ll likely receive an encrypted file containing both the certificate and its private key. Depending on the exact nature of the file format, Windows provides several commands to import certificates in to one of its certificate stores.

For instance, this will a import PFX file in to the `Personal` certificate store of `Current User`:

    C:\...>certutil.exe -user -importpfx -p MySecretPassword My .\cert.pfx

    PS C:\...> Import-PfxCertificate -FilePath .\cert.pfx -CertStoreLocation Cert:\CurrentUser\My -Password MySecretPassword

Refer to your Certificate Authority’s documentation for specific instructions.

## Certificate’s SHA-1 Thumbprint

On Windows, briefcase package cannot retrieve the list of installed code signing certificates automatically. You need to retrieve the identity manually, and provide the certificates identity as a command line argument.

The certificates installed on the machine are available in the Certificate Manager. Search for “User Certificates” in the Start Menu to access certificates for `Current User` or search for “Computer Certificates” for certificates for `Local Machine`. Alternatively, the command `certmgr.msc` will open the manager for `Current User` and `certlm.msc` for `Local Machine`.

Once you locate your certificate in the certificate store it was installed in to, double-click it to access information about it. Near the bottom of the list on the Details tab, you’ll find the `Thumbprint` field with the 40 character SHA-1 hash to use as the `identity` in the Briefcase package command.

    (venv) C:\...>briefcase package --identity <certificate thumbprint>