As part of rooting a device, I need to generate a 256-byte RSASSA-PSS signature using SHA256 as the hash and MGF1-SHA256 as the mask function, for an update file I created. I can choose any 32-byte key; moreover, I am provided with a default key, namely
However, I have no clue what those terms mean (e.g. mask function???). The rooting guide refers to a specification sheet online, that details how these encryption algorithms work. Would I have to follow all the steps in that file one by one, or has this algorithm already been programmed somewhere, in a way that I can provide the file and the key, and it can give me the 256-byte hash?
I apologize in advance if this is not the type of questions that are typically asked on the crypto site; but I asked on the meta, and did not get a response about where I can ask this; and, this is the last step of a day-long root, so I really wish to get this done.