With the release of Unreal Engine 4.22, we enhanced project data security by replacing our custom RSA implementation with the industry standard OpenSSL library, which makes undetected tampering more difficult. This improves the effectiveness of pak signing support on desktop platforms, including Windows, Mac, and Linux. At this time, the OpenSSL integration for pak signing is only available on these platforms, but we are planning on extending this integration to our other supported platforms in a future engine release.
To learn more about this improvement, read about it in the Core Upgrade Notes for the 4.22 release. And if you want to learn more about pak signing in Unreal Engine, check out the Signing and Encryption section of our Packaging documentation.