Tested on game 1.0.0.5 from the Epic Games Store. The hash is recorded in the save so that the game accepts it.

Default saves: Documents/Salt and Sacrifice/savedata/*.slv

The program converts .slv saves into .json files and vice versa. You just need to pass them to the program at startup, i.e. drag and drop onto the application or run from the command line with the path to the file.