How to use the esptool.ESP32FirmwareImage function in esptool

def __init__(self, load_file=None):
        super(ESP32FirmwareImage, self).__init__()
        self.secure_pad = False
        self.flash_mode = 0
        self.flash_size_freq = 0
        self.version = 1
        self.wp_pin = self.WP_PIN_DISABLED
        # SPI pin drive levels
        self.clk_drv = 0
        self.q_drv = 0
        self.d_drv = 0
        self.cs_drv = 0
        self.hd_drv = 0
        self.wp_drv = 0

        self.append_digest = True

        if load_file is not None:

def digest_secure_bootloader(args):
    """ Calculate the digest of a bootloader image, in the same way the hardware
    secure boot engine would do so. Can be used with a pre-loaded key to update a
    secure bootloader. """
    if args.iv is not None:
        print("WARNING: --iv argument is for TESTING PURPOSES ONLY")
        iv = args.iv.read(128)
    else:
        iv = os.urandom(128)
    plaintext_image = args.image.read()
    args.image.seek(0)

    # secure boot engine reads in 128 byte blocks (ie SHA512 block
    # size), but also doesn't look for any appended SHA-256 digest
    fw_image = esptool.ESP32FirmwareImage(args.image)
    if fw_image.append_digest:
        if len(plaintext_image) % 128 <= 32:
            # ROM bootloader will read to the end of the 128 byte block, but not
            # to the end of the SHA-256 digest at the end
            new_len = len(plaintext_image) - (len(plaintext_image) % 128)
            plaintext_image = plaintext_image[:new_len]

    # if image isn't 128 byte multiple then pad with 0xFF (ie unwritten flash)
    # as this is what the secure boot engine will see
    if len(plaintext_image) % 128 != 0:
        plaintext_image += b"\xFF" * (128 - (len(plaintext_image) % 128))

    plaintext = iv + plaintext_image

    # Secure Boot digest algorithm in hardware uses AES256 ECB to
    # produce a ciphertext, then feeds output through SHA-512 to

def elf2image(args):
    e = ELFFile(args.input)
    if args.chip == 'auto':  # Default to ESP8266 for backwards compatibility
        print("Creating image for ESP8266...")
        args.chip = 'esp8266'

    if args.chip == 'esp32':
        image = ESP32FirmwareImage()
        image.secure_pad = args.secure_pad
    elif args.version == '1':  # ESP8266
        image = ESP8266ROMFirmwareImage()
    else:
        image = ESP8266V2FirmwareImage()
    image.entrypoint = e.entrypoint
    image.segments = e.sections  # ELFSection is a subclass of ImageSegment
    image.flash_mode = {'qio':0, 'qout':1, 'dio':2, 'dout': 3}[args.flash_mode]
    image.flash_size_freq = image.ROM_LOADER.FLASH_SIZES[args.flash_size]
    image.flash_size_freq += {'40m':0, '26m':1, '20m':2, '80m': 0xf}[args.flash_freq]

    if args.output is None:
        args.output = image.default_output_name(args.input)
    image.save(args.output)

def LoadFirmwareImage(chip, filename):
    """ Load a firmware image. Can be for ESP8266 or ESP32. ESP8266 images will be examined to determine if they are
        original ROM firmware images (ESP8266ROMFirmwareImage) or "v2" OTA bootloader images.

        Returns a BaseFirmwareImage subclass, either ESP8266ROMFirmwareImage (v1) or ESP8266V2FirmwareImage (v2).
    """
    with open(filename, 'rb') as f:
        if chip.lower() == 'esp32':
            return ESP32FirmwareImage(f)
        else:  # Otherwise, ESP8266 so look at magic to determine the image type
            magic = ord(f.read(1))
            f.seek(0)
            if magic == ESPLoader.ESP_IMAGE_MAGIC:
                return ESP8266ROMFirmwareImage(f)
            elif magic == ESPBOOTLOADER.IMAGE_V2_MAGIC:
                return ESP8266V2FirmwareImage(f)
            else:
                raise FatalError("Invalid image magic number: %d" % magic)

def elf2image(args):
    e = ELFFile(args.input)
    if args.chip == 'auto':  # Default to ESP8266 for backwards compatibility
        print("Creating image for ESP8266...")
        args.chip = 'esp8266'

    if args.chip == 'esp32':
        image = ESP32FirmwareImage()
        image.secure_pad = args.secure_pad
    elif args.version == '1':  # ESP8266
        image = ESP8266ROMFirmwareImage()
    else:
        image = ESP8266V2FirmwareImage()
    image.entrypoint = e.entrypoint
    image.segments = e.sections  # ELFSection is a subclass of ImageSegment
    image.flash_mode = {'qio':0, 'qout':1, 'dio':2, 'dout': 3}[args.flash_mode]
    image.flash_size_freq = image.ROM_LOADER.FLASH_SIZES[args.flash_size]
    image.flash_size_freq += {'40m':0, '26m':1, '20m':2, '80m': 0xf}[args.flash_freq]

    if args.elf_sha256_offset:
        image.elf_sha256 = e.sha256()
        image.elf_sha256_offset = args.elf_sha256_offset

    image.verify()

def LoadFirmwareImage(chip, filename):
    """ Load a firmware image. Can be for ESP8266 or ESP32. ESP8266 images will be examined to determine if they are
        original ROM firmware images (ESP8266ROMFirmwareImage) or "v2" OTA bootloader images.

        Returns a BaseFirmwareImage subclass, either ESP8266ROMFirmwareImage (v1) or ESP8266V2FirmwareImage (v2).
    """
    with open(filename, 'rb') as f:
        if chip.lower() == 'esp32':
            return ESP32FirmwareImage(f)
        else:  # Otherwise, ESP8266 so look at magic to determine the image type
            magic = ord(f.read(1))
            f.seek(0)
            if magic == ESPLoader.ESP_IMAGE_MAGIC:
                return ESP8266ROMFirmwareImage(f)
            elif magic == ESPBOOTLOADER.IMAGE_V2_MAGIC:
                return ESP8266V2FirmwareImage(f)
            else:
                raise FatalError("Invalid image magic number: %d" % magic)

def digest_secure_bootloader(args):
    """ Calculate the digest of a bootloader image, in the same way the hardware
    secure boot engine would do so. Can be used with a pre-loaded key to update a
    secure bootloader. """
    if args.iv is not None:
        print("WARNING: --iv argument is for TESTING PURPOSES ONLY")
        iv = args.iv.read(128)
    else:
        iv = os.urandom(128)
    plaintext_image = args.image.read()
    args.image.seek(0)

    # secure boot engine reads in 128 byte blocks (ie SHA512 block
    # size), but also doesn't look for any appended SHA-256 digest
    fw_image = esptool.ESP32FirmwareImage(args.image)
    if fw_image.append_digest:
        if len(plaintext_image) % 128 <= 32:
            # ROM bootloader will read to the end of the 128 byte block, but not
            # to the end of the SHA-256 digest at the end
            new_len = len(plaintext_image) - (len(plaintext_image) % 128)
            plaintext_image = plaintext_image[:new_len]

    # if image isn't 128 byte multiple then pad with 0xFF (ie unwritten flash)
    # as this is what the secure boot engine will see
    if len(plaintext_image) % 128 != 0:
        plaintext_image += b"\xFF" * (128 - (len(plaintext_image) % 128))

    plaintext = iv + plaintext_image

    # Secure Boot digest algorithm in hardware uses AES256 ECB to
    # produce a ciphertext, then feeds output through SHA-512 to