code: def encrypt_buf_automation(
      ip,
      port,
      buf: io.BytesIO,
      encrypted_buf: io.BytesIO,
      encrypted_primary_key_path,
      encrypted_data_key_path,
  ):
      data_key = retrieve_data_key_plaintext(
          ip, port, encrypted_primary_key_path, encrypted_data_key_path
      )
      fernet = Fernet(data_key)
      content = buf.getvalue()
      encrypted_content = fernet.encrypt(content)
      encrypted_buf.write(encrypted_content)
  
file_path: BigDL/python/ppml/src/bigdl/ppml/kms/ehsm/file_operator.py
imports: from key_manager import retrieve_data_key_plaintext
  from cryptography.fernet import Fernet
  import os, csv, io
label_desc: Use image node_id 7 for calling a global function with example usage: encrypt_buf_automation(ip, port, buf, encrypted_buf, encrypted_primary_key_path, encrypted_data_key_path) without return types