问题
Is there any way to obscure the schema of a database on SQL Server?
If I have SQL Server Express installed on a client site, is there a way to obscure the schema and data so that someone else cannot come along and learn the schema in order to extract data out of it and into another product?
回答1:
This is a tricky one and may not even be 100% possible. However, there are a few tricks to setting it up:
- Install a new named instance of SQL server with a custom SA account (both name and password). There is an installation method for SQL server call "Unattended Installation" which allows you to specify all the installation parameters for SQL server in an ini file and then run the install silently. Check out the documentation here: Unattended Installation of SQL Server 2008 r2
- Create your database, tables, procedures, etc. with your magic SQL install script (use encrypted stored procs if you want, but they too are crackable)
- Add/Verify the schema permissions for the custom SA account and Drop all schema permissions for all Administrator roles. The goal here is that no roles have any schema permissions to your database and only your custom SA user has permission (not assigned by role, but directly to the user).
There are several commercial applications that I know of that don't even tell you they are installing an instance of MS SQL express. They too will create their own named instance with a named SA account. I can't say I like that as a customer (as SQL takes a hit on the CPU and I don't want "secret" instances running on my workstation). But so long as you disclose this to your customers upfront, they may understand.
**Keep in mind a skilled DBA may have the knowledge to mess with system tables and what not to manually grant access to your database. These techniques really are just "obfuscation" and won't be 100% bullet proof.
As a side note: With the plethora of available 3rd party datalayers and webservice technologies, I think many companies are finding their database schema alone isn't so proprietary or valuable anymore. There was a time when the database schema alone could have represented hundreds of hours of coding. But today tools like EntityFramework, NHibernate, Linq-to-SQL, XPO, etc all create your database schema for you based on your software class definitions and in code attributes. So just seeing a DB table isn't really very valuable. Plus you might write a bunch of business logic, statistical analysis or other helper methods in your software that aren't in your database schema. In my opinion, this is where today's "value add" is found, in the business logic, analysis and reporting functionality of your software - not in the raw datatables.
This is also why another poster recommended obfuscating stored procedures, because these could be many times the work of the database schema itself if you have some nice analysis and reporting procedures written up. Its also what customer's would most likely want to customize for their own reporting needs. You may be inclined to have a policy that custom reporting can only be done by your company (hey, even the big guys like SAP are sticky with who can modify what).
回答2:
The best way to obscure your database schema is to not let it leave your servers.
Even if you encrypt the schema you still will have to provide the key somewhere, and if the client is determined to get it, they'll spend time and money to do so.
So you're better off either offering your product as service or making your client loyal by doing good job.
回答3:
AFAIK, "no".
The best way to "lock down" your database is:
1) Install with appropriate roles and users (ideally, SQL roles and SQL users you create)
2) Explicitly restrict object permissions in SQL Server
3) Code your application to use SQL Server stored procedures (instead of raw T-SQL) as much as possible
4) Encrypt your stored procedures
Here's a good link on "SQL Server Best Practices" that might be of interest. It discusses security issues and a (relatively) new feature, "User Schema Separation":
- http://msdn.microsoft.com/en-us/library/dd283095%28v=sql.100%29.aspx
回答4:
There is a way, it's convoluted and ugly but it works.
You have a master table that acts as a lookup table for your other tables. This master table would look sort of like this:
id, guid, entityname, parent_id
then all of your table names and column names get renamed to be guids. after that you put an entry in the lookup table for each of them. When you want to select data you have to do so by pulling the guid's out of the lookup table by their entitynames which then give you the obscured table and column names.
There is a major software vendor out there that does something very similar to this, so it has been done before.
来源：https://stackoverflow.com/questions/8265664/way-to-obscure-sql-server-database-schema