How to use the buku.BukuCrypt function in buku

# Get original DB file's SHA256 hash from encrypted file
                enchash = infp.read(32)

                with open(dbfile, 'wb') as outfp:
                    while True:
                        chunk = infp.read(BukuCrypt.CHUNKSIZE)
                        if len(chunk) == 0:
                            break

                        outfp.write(decryptor.update(chunk) + decryptor.finalize())

                    outfp.truncate(size)

            # Match hash of generated file with that of original DB file
            dbhash = BukuCrypt.get_filehash(dbfile)
            if dbhash != enchash:
                os.remove(dbfile)
                logerr('Decryption failed')
                sys.exit(1)
            else:
                os.remove(encfile)
                print('File decrypted')
        except struct.error:
            logerr('Tainted file')
            sys.exit(1)
        except Exception as e:
            logerr(e)
            sys.exit(1)

for _ in range(iterations):
                    key = sha256(key).digest()

                iv = infp.read(16)
                decryptor = Cipher(
                    algorithms.AES(key),
                    modes.CBC(iv),
                    backend=default_backend(),
                ).decryptor()

                # Get original DB file's SHA256 hash from encrypted file
                enchash = infp.read(32)

                with open(dbfile, 'wb') as outfp:
                    while True:
                        chunk = infp.read(BukuCrypt.CHUNKSIZE)
                        if len(chunk) == 0:
                            break

                        outfp.write(decryptor.update(chunk) + decryptor.finalize())

                    outfp.truncate(size)

            # Match hash of generated file with that of original DB file
            dbhash = BukuCrypt.get_filehash(dbfile)
            if dbhash != enchash:
                os.remove(dbfile)
                logerr('Decryption failed')
                sys.exit(1)
            else:
                os.remove(encfile)
                print('File decrypted')

if not password or not passconfirm:
            logerr('Empty password')
            sys.exit(1)
        if password != passconfirm:
            logerr('Passwords do not match')
            sys.exit(1)

        try:
            # Get SHA256 hash of DB file
            dbhash = BukuCrypt.get_filehash(dbfile)
        except Exception as e:
            logerr(e)
            sys.exit(1)

        # Generate random 256-bit salt and key
        salt = os.urandom(BukuCrypt.SALT_SIZE)
        key = ('%s%s' % (password, salt.decode('utf-8', 'replace'))).encode('utf-8')
        for _ in range(iterations):
            key = sha256(key).digest()

        iv = os.urandom(16)
        encryptor = Cipher(
            algorithms.AES(key),
            modes.CBC(iv),
            backend=default_backend()
        ).encryptor()
        filesize = os.path.getsize(dbfile)

        try:
            with open(dbfile, 'rb') as infp, open(encfile, 'wb') as outfp:
                outfp.write(struct.pack('

Parameters
        ----------
        filepath : str
            Path to the file

        Returns
        -------
        hash : bytes
            Hash digest of file
        """

        from hashlib import sha256

        with open(filepath, 'rb') as fp:
            hasher = sha256()
            buf = fp.read(BukuCrypt.BLOCKSIZE)
            while len(buf) > 0:
                hasher.update(buf)
                buf = fp.read(BukuCrypt.BLOCKSIZE)

            return hasher.digest()