How to Enforce Encryption in Transit in SQL Server

How do I enable TLS encryption in transit on SQL Server?

Encrypts the wire protocol (TDS) so every client-server packet is protected by TLS.

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Description

Why require TLS for SQL Server connections?

Encrypting in transit thwarts packet sniffing, keeps customer emails, order totals, and product prices unreadable, and satisfies PCI-DSS, HIPAA, and SOC2 controls.

How do I create a server certificate quickly?

What T-SQL generates a self-signed cert?

Run CREATE CERTIFICATE to spin up a short-lived test certificate while waiting on a CA-signed one.

How do I bind the certificate to the TDS endpoint?

Use CREATE ENDPOINT or ALTER ENDPOINT with the CERTIFICATE option, then force encryption using STATE = STARTED and ENCRYPTION = REQUIRED.

Which driver flags enable encryption?

Add Encrypt=True and TrustServerCertificate=False to ADO.NET, ODBC, or JDBC connection strings so clients negotiate TLS automatically.

How can I confirm the session is encrypted?

Query sys.dm_exec_connections; the encrypt_option column shows TRUE when TLS is active.

Best practices for production certificates

Use a CA-signed certificate whose CN or SAN matches the server’s DNS name, set a 1-2 year expiry, and store the private key in the Windows certificate store with minimal ACLs.

How do I roll certificates with zero downtime?

Import the new certificate, bind it to the endpoint, then restart the SQL Server service during a maintenance window; clients reconnect automatically.

Why How to Enforce Encryption in Transit in SQL Server is important

How to Enforce Encryption in Transit in SQL Server Example Usage


--Verify encryption and return all paid orders
SELECT encrypt_option
FROM sys.dm_exec_connections
WHERE session_id = @@SPID;

SELECT o.id, c.name, o.total_amount
FROM Orders o
JOIN Customers c ON c.id = o.customer_id
WHERE o.total_amount > 0;

How to Enforce Encryption in Transit in SQL Server Syntax


--1. Create a database master key
CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'Str0ngP@ss!';

--2. Generate a self-signed certificate on the server
CREATE CERTIFICATE SalesTLSCert
    WITH SUBJECT = 'TLS for ecommerce traffic',
         EXPIRY_DATE = '2030-12-31';

--3. Expose a secure endpoint (uses default TCP 1433)
CREATE ENDPOINT [TdsTls]
    STATE = STARTED
    AS TSQL()
    FOR TSQL()
    ENCRYPTION ( ALGORITHM = AES, CERTIFICATE = SalesTLSCert, ENCRYPTION = REQUIRED );

--4. Force the SQL Server service to use the cert (SQL Server Configuration Manager)
--   SQL Server Network Configuration → Protocols → Properties → Flags → Force Encryption = Yes

--5. Client connection string (ADO.NET)
Server=tcp:prod-sql.acme.com,1433;Database=StoreDB;Encrypt=True;TrustServerCertificate=False;User ID=app;Password=*****;

Common Mistakes

Installing a certificate whose CN does not match the server’s DNS name. Clients then refuse the connection unless TrustServerCertificate=True, defeating security. Always request a cert for the exact FQDN.
Leaving TrustServerCertificate=True in production connection strings. This bypasses certificate chain validation and allows man-in-the-middle attacks. Set it to False once a valid cert is installed.