i just tried it to decrypt a EDAT file from Jetpack Joyride , seems to be not working . Probably flag 0x3C and 0x3D are unsupported yet.
E:\rpcs3-master\npdtool>make_npdata -d jet.pak.edat output.edat UP4249-NPUB31097_00-JETPACKJOYRIDE00.rap
NPD HEADER
NPD version: 4
NPD license: 2
NPD type: 0
EDAT HEADER
EDAT flags: 0x0000003C
EDAT block size: 0x00004000
EDAT file size: 0x00BAB567
ERROR: A valid RAP file is needed for this EDAT file!
E:\rpcs3-master\npdtool>make_npdata -d jet.pak.edat output.edat UP4249-NPUB31097_00-JETPACKJOYRIDE00.rap
NPD HEADER
NPD version: 4
NPD license: 2
NPD type: 0
EDAT HEADER
EDAT flags: 0x0000003C
EDAT block size: 0x00004000
EDAT file size: 0x00BAB567
ERROR: A valid RAP file is needed for this EDAT file!