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SQL Server provides a robust set of advanced security features designed to protect data from unauthorized access and malicious attacks. It does so through the implementation of a number of security technologies, including Transparent Data Encryption, Always Encrypted, and Row-Level Security, among others. This guide will explore these security features, providing example SQL Server code to illustrate their application.
Transparent Data Encryption (TDE)
Transparent Data Encryption (TDE) is a security feature that provides at-rest encryption for database files. TDE prevents unauthorized access from people who gain access to the database file or backups.
The following SQL code example shows how to enable TDE on your database:
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USE master; GO CREATE MASTER KEY ENCRYPTION BY PASSWORD = '<UseStrongPasswordHere>'; GO CREATE CERTIFICATE MyServerCert WITH SUBJECT = 'My DEK Certificate'; GO USE AdventureWorks2012; GO CREATE DATABASE ENCRYPTION KEY WITH ALGORITHM = AES_128 ENCRYPTION BY SERVER CERTIFICATE MyServerCert; GO ALTER DATABASE AdventureWorks2012 SET ENCRYPTION ON; GO |
Always Encrypted
Always Encrypted is a security feature designed to ensure sensitive data, such as credit card numbers or national identification numbers, remain encrypted both at rest and in transit between the application and SQL Server.
Here’s an example of parameterizing a query to use Always Encrypted:
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SqlParameter parameter = new SqlParameter(); parameter.ParameterName = "@AccountNumber"; parameter.SqlDbType = SqlDbType.NVarChar; parameter.Direction = ParameterDirection.Input; parameter.Value = accountNumber; parameter.IsNullable = false; command.Parameters.Add(parameter); |
Row-Level Security
Row-Level Security (RLS) is a feature that allows SQL Server to restrict access to rows of data based on user identity or security context. This restriction happens transparently to the application, ensuring that users only access the data they’re authorized to see.
Here’s a sample SQL code demonstrating how to implement RLS:
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CREATE SCHEMA Security; GO CREATE FUNCTION Security.fn_securitypredicate(@SalesRep AS sysname) RETURNS TABLE WITH SCHEMABINDING AS RETURN SELECT 1 AS fn_securitypredicate_result WHERE @SalesRep = USER_NAME(); GO CREATE SECURITY POLICY SalesFilter ADD FILTER PREDICATE Security.fn_securitypredicate(SalesRep) ON dbo.Sales WITH (STATE = ON); |
In conclusion, SQL Server has robust security features that can safeguard your data against malicious attacks. It is important to understand these features and apply them as necessary in your data environment.