Encoding a hexidecimal Ed25519 verify key to DER format using Node.

ed25519.js

const crypto = require('crypto')

{
  const verifyKey = 'e8601e48b69383ba520245fd07971e983d06d22c4257cfd82304601479cee788'
  const licenseKey = 'key/Njg1ZjkwMDY5OGZkOWNiZTYwODRlNmRhZDdmMGU3NjI=.V0MIuqrUfTnPrCAPqi8YfnpGHNluoGs1QG0XqZ67D8q9dQvtuEaKVz_7w5cZkcYvOkNbvE28w8P4xVemXbBqAA=='

  // Encode hexidecimal key into DER format (Node doesn't accept hex format)
  const oid = Buffer.from([0x06, 0x03, 0x2B, 0x65, 0x70])
  const key = Buffer.from(verifyKey, 'hex')
  const elements = Buffer.concat([
    Buffer.concat([
      Buffer.from([0x30]), // Sequence tag
      Buffer.from([oid.length]),
      oid,
    ]),
    Buffer.concat([
      Buffer.from([0x03]), // Bit tag
      Buffer.from([key.length + 1]),
      Buffer.from([0x00]), // Zero bit
      key,
    ]),
  ])

  const der = Buffer.concat([
    Buffer.from([0x30]), // Sequence tag
    Buffer.from([elements.length]),
    elements,
  ])
  
  // Initialize our public key
  const publicKey = crypto.createPublicKey({ key: der, type: 'spki', format: 'der' })
  
  // Decode and verify the license key
  const [signingData, encodedSignature] = licenseKey.split('.')
  const [signingPrefix, encodedData] = signingData.split('/')
  const signature = Buffer.from(encodedSignature, 'base64')
  const data = Buffer.from(encodedData, 'base64').toString()

  const ok = crypto.verify(null, Buffer.from(signingData), publicKey, signature)

  console.log({ ok, data })
}