# Type of request: This is a ...
[ ] bug report
[x] feature request

# Detailed description
As a Developer,
I want to be able to simulate BadDigest and InvalidDigest errors,
So that I can test the error handling logic

## Expected behavior
https://docs.aws.amazon.com/AmazonS3/latest/API/ErrorResponses.html
BadDigest: The Content-MD5 you specified did not match what we received.
InvalidDigest: The Content-MD5 you specified is not valid.

## Actual behavior
localstack returns InvalidDigest when MD5 does not match payload.


import functools
from io import BytesIO
from contextlib import closing
from datetime import datetime, date
from six import with_metaclass
from six.moves import cStringIO as StringIO
from six.moves.urllib.parse import urlparse
from multiprocessing.dummy import Pool
from localstack import config
from localstack.config import DEFAULT_ENCODING
from localstack.constants import ENV_DEV
from localstack.utils import bootstrap
from localstack.utils.bootstrap import FuncThread
TMP_FILES = []
TMP_THREADS = []
TMP_PROCESSES = []
CACHE_CLEAN_TIMEOUT = 60 * 5
CACHE_MAX_AGE = 60 * 60
CACHE_FILE_PATTERN = os.path.join(tempfile.gettempdir(), '_random_dir_', 'cache.*.json')
last_cache_clean_time = {'time': 0}
mutex_clean = threading.Semaphore(1)
TIMESTAMP_FORMAT = '%Y-%m-%dT%H:%M:%S'
TIMESTAMP_FORMAT_MICROS = '%Y-%m-%dT%H:%M:%S.%fZ'
CODEC_HANDLER_UNDERSCORE = 'underscore'
DOWNLOAD_CHUNK_SIZE = 1024 * 1024
LOG = logging.getLogger(__name__)
INFRA_STOPPED = False
CACHE = {}
SSL_CERT_LOCK = threading.RLock()
class CustomEncoder(json.JSONEncoder):