# 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.


dynamodb = aws_stack.connect_to_service('dynamodb')
        aws_stack.create_dynamodb_table(TEST_DDB_TABLE_NAME, partition_key=PARTITION_KEY)
        table = self.dynamodb.Table(TEST_DDB_TABLE_NAME)
        item_id = short_uid()
        table.put_item(Item={PARTITION_KEY: item_id, 'data': 'foobar123 ✓'})
        response = dynamodb.update_item(TableName=TEST_DDB_TABLE_NAME,
            Key={PARTITION_KEY: {'S': item_id}},
            UpdateExpression='SET attr1 = :v1, attr2 = :v2',
            ExpressionAttributeValues={
                ':v1': {'S': 'value1'},
                ':v2': {'S': 'value2'}
            })
        self.assertEqual(response['ResponseMetadata']['HTTPStatusCode'], 200)
        item = table.get_item(Key={PARTITION_KEY: item_id})['Item']
        self.assertEqual(item['attr1'], 'value1')
        self.assertEqual(item['attr2'], 'value2')
    def test_return_values_in_put_item(self):