If you select FormsProtectionEnum.None, cookies might be subject to plaintext attacks.
If you select FormsProtectionEnum.Validation, the cookie is created using cookie validation by concatenating a validation key with the cookie data, computing a Message Authentication Code (MAC), and appending the MAC to the outgoing cookie.
Specifies that the application use both data validation and encryption to help protect cookies. This option uses the configured data-validation algorithm (based on the machineKey element). Triple-DES (3DES) is used for encryption, if it is available and if the key is at least 48 bytes long. All is the default (and recommended) value.
Specifies that cookies are encrypted using Triple-DES or DES, but data validation is not performed on cookies. Cookies used this way might be subject to chosen plaintext security attacks.
Specifies that the application use a validation scheme to verify that the contents of an encrypted cookie have not been altered in transit. The cookie is created by concatenating a validation key with the cookie data, computing a Message Authentication Code (MAC), and appending the MAC to the outgoing cookie.