Let's assume I want to use an open-source software, the developer says that the software is open-source and provides the source code.
Now my question is, how can I be 100% sure that the given binary files are compiled from the given source code?
Of course I could always compile the source code of every open source project I want to make use of but that is quite time-consuming if I want to use more than just one program or even not possible if I want to use for example an iPhone and do not have a macbook.
So do I have to trust the developer that the binary files are truly from that source code or is there another way?
For example: Let's assume I want to use the messenger app Signal. How can I be sure that there is not a built-in backdoor in the binary files which is not in the provided source code?