zecoxao ported flat_z’s EID Root Key Dumper to CFW 4.21, 4.46 and 4.53, allowing root EID key extraction without need for downgrade.
Update: zecoxao added a port to 4.65 (also in the links).
You will find your root key at dev_hdd0/game/FLTZ00010/USRDIR.
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