Some Mac owners experience the unrusted_cert_title error when trying to reinstall macOS. This problem occurs when the Mac system clock is not set correctly, and you may encounter a chicken-and-egg problem: without a macro program installed, there is no easy way to set the clock that will allow the macro program to be installed.
To establish a secure connection, many encryption algorithms require an up-to-date clock. The encryption system wants to check if the digital certificate confirming the integrity of the software has not yet expired. If the data embedded in the certificate is earlier than the release date or later than the expiration date, the software is properly locked – and MacOS, unfortunately, spits out an error, since this feature has not yet been accounted for in Mojave.