obfuscate ttf file to odttf file, asked ChatGPT4 to reverse https://gist.github.com/jacwright/40c50faa29257c8b76666c1e077352f1

obfuscate-ttf-odttf.js

const purpose = "Purpose: obfuscate ttf file (convert to Microsoft's ODTTF format)"
const usage = "Usage: node obfuscate-ttf-to-odttf.js <guid-font-file.ttf> [<output-file.odttf>]"

const obfuscatedStartOffset = 0
const obfuscatedEndOffset = 32
const guidSize = 32

const fs = require('fs')
const path = require('path')

const fontFilepath = process.argv[2]
if (fontFilepath == null) {
	console.warn(purpose)
	console.warn(usage)
	return
}

const fontFilename = path.basename(fontFilepath)
const guid = fontFilename.replace(/-/g, "").replace(/\..+$/, "")
if (guid.length !== guidSize) {
	console.warn(guid, "Error: Cannot extract GUID from font filename (ex: A5C0272A-DD4C-401C-8661-BEAD77E57818.ttf)")
	return
}

const hexStrings = guid.replace(/(..)/g,"$1 ").trim().split(" ")
const hexNumbers = hexStrings.map((hexString) => parseInt(hexString, 16))
hexNumbers.reverse()

const buf = fs.readFileSync(fontFilepath)
const bytesToObfuscate = buf.slice(obfuscatedStartOffset, obfuscatedEndOffset)
const obfuscatedBytes = bytesToObfuscate.map((byte, i) => byte ^ hexNumbers[i % hexNumbers.length] )

const out = Buffer.concat([
	buf.slice(0, obfuscatedStartOffset),
	obfuscatedBytes,
	buf.slice(obfuscatedEndOffset)
	])
const outputFilepath = process.argv[3] || fontFilepath + '.odttf'
fs.writeFile(
	outputFilepath,
	out,
	{ encoding: null },
	(error) => { if (error) throw error; }
	)