Well you're right about the files not being in the SDK. But I checked the keys against the ones I managed to extract from the SDK, and they are some of the real dev keys. You can sign DEV CIAs, ROMs, CFAs and CRRs with these keys. Though I don't know why someone would leak these, they're of no use to those without developer 3DSs.I returned, just to confirm, that this is all fake.
Every single file in that 7z file, cannot be found in the actual 3DS SDK, and I'm probably the only person here who can know that.
EDIT: You're a dev now Congrats