input = open('policy.txt', 'rb')
policy = input.read()
policy_encoded = base64.b64encode(policy)
signature = base64.b64encode(hmac.new(private_key, policy_encoded, sha).
    digest())
print('Your policy base-64 encoded is %s.' % policy_encoded)
print('Your signature base-64 encoded is %s.' % signature)
print('Your signature encoded should be 2qCp0odXe7A9IYyUVqn0w2adtCA=')
Сгенерированная Python подпись для сообщения S3