C:\WINDOWS\Microsoft.NET\Framework\<.Net Version Folder>\aspnet_regiis.exe -pef "<Secton to encrypt in Web.Config>" "<Path to Web.Config>" -prov "DataProtectionConfigurationProvider"
C:\WINDOWS\Microsoft.NET\Framework\<.Net Version Folder>\aspnet_regiis.exe -pdf "<Secton to decrypt in Web.Config>" "<Path to Web.Config>"
Note: Only certain sections can be encrypted.