iOS requires all code running on the device to be signed using a valid Apple-issued certificate, to ensure integrity and that they come from a trusted source. Unlike macOS, this rule is enforced and the sideloading of apps outside the App Store is not supported for purposes other than app development. A notable exception to this rule is code signed with enterprise program certificates, whose aim is mainly to allow the distribution of proprietary software for internal use, or beta versions for testing within an organization only. Later, we will see how this technology can be misused by malware. Usually, this is done using MDM; in this case, a special enterprise-provisioning profile is created on the device.
Once the developer joins the Apple developer program, their identity needs to be verified before the certificate can be issued. Since 2015, there is also an option for developers to sign their code for free, but it has multiple limitations, such as a short expiration...