# 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.


bucket_name = 'test-presigned-%s' % short_uid()
        self.s3_client.create_bucket(Bucket=bucket_name)
        body = 'something body'
        
        object_key = 'test-presigned-post-key'
        presigned_request = self.s3_client.generate_presigned_post(
            Bucket=bucket_name, Key=object_key, ExpiresIn=60)
        
        files = {'file': body}
        response = requests.post(presigned_request['url'], data=presigned_request['fields'], files=files, verify=False)
        self.assertIn(response.status_code, [200, 204])
        
        downloaded_object = self.s3_client.get_object(Bucket=bucket_name, Key=object_key)
        download_object = downloaded_object['Body'].read()
        self.assertEqual(to_str(body), to_str(download_object))
        
        self._delete_bucket(bucket_name, [object_key])
    def test_s3_presigned_post_expires(self):