extract LBP PSP 128-bit decryption kley

extract.js

const fs = require("fs");

//key.bin is a file containing the extracted 64-byte region starting from 0x003d9f30 in the decrypted LBP PSP US 2.0.5 EBOOT.BIN
let block = fs.readFileSync('key.bin');
let key = Buffer.alloc(16);
for (let i = 0; i < 16; ++i)
    key[i] = block[(i * 4) + (i % 4)];

//psp.key is the output key.
fs.writeFileSync('psp.key', key);