Pentru criptarea comunicării cu serverul MSSQL, folosește un connection string cu encrypt=true:
<connectionStrings>
<add name="MyConnection"
connectionString="Data Source=tcp:numeserver;Initial Catalog=DB_XXX_db1;User ID=DB1_user;Password=*****;encrypt=true"
providerName="System.Data.SqlClient" />
</connectionStrings>