How to use the @aws-crypto/serialize.der2raw function in @aws-crypto/serialize

const info = kdfInfo(suiteId, messageId)
  const getSubtleDecrypt = kdfGetSubtleDecrypt(info)

  // The tag is appended to the Data
  await getSubtleDecrypt(headerIv, rawHeader)(headerAuthTag) // will throw if invalid

  const { plaintext, readPos } = await bodyDecrypt({ buffer: ciphertext, getSubtleDecrypt, headerInfo })

  dispose()

  if (subtleVerify) {
    const data = ciphertext.slice(0, readPos)
    const signatureInfo = ciphertext.slice(readPos)

    const derSignature = deserializeSignature(signatureInfo)
    const rawSignature = der2raw(derSignature, material.suite)

    const isValid = await subtleVerify(rawSignature, data)
    /* Postcondition: subtleVerify must validate the signature. */
    needs(isValid, 'Invalid Signature')
    return { messageHeader, plaintext }
  } else {
    return { messageHeader, plaintext }
  }
}