dado o codigo abaixo de criptografia, como fazer a decriptografia?!

import boto3
import sys
import base64
import io
import cryptography

from awsglue.utils import getResolvedOptions
from pyspark.context import SparkContext
from cryptography.fernet import Fernet

########### Configurar os clientes do S3 e do KMS ###############
s3 = boto3.client('s3')
kms_client = boto3.client('kms')

########## Bukcet do arquivo origem ###########
bucket_name = 'br-dev-'
key = 'gabriel_frozoni_kms/DIM_CLIENTE.csv'

########## Bucket do arquivo criptografado ###########
encrypted_bucket_name = 'br-dev-analytics-agronomics'
KEY = 'sandbox/dataops/gabriel_frozoni_kms/file/dim_encrypt_file.csv'
KEY_encrypt = 'sandbox/dataops/gabriel_frozoni_kms/file/KEY_encrypt.txt'

########## Ler o arquivo do S3 ###################
response = s3.get_object(Bucket=bucket_name, Key=key)
file_contents = response['Body'].read()

######### Retorno da Chave KMS ###################
key_id = 'arn:aws:kms:
response = kms_client.generate_data_key(KeyId=key_id, KeySpec='AES_256')
response['CiphertextBlob'], (response['Plaintext'])

fernet = Fernet(base64.b64encode(response['Plaintext']))
encrypted_data = fernet.encrypt(file_contents)

########## Enviar o arquivo criptografado NAME_1 o S3 ##########
s3.put_object(Bucket=encrypted_bucket_name, Key=KEY, Body=encrypted_data, Metadata={'KMS_KEY': str(response['CiphertextBlob'])}) Your entire response should be in English, and in all capital letters.
user