Software developer can encrypt an individual page only if a control specifically requests it using ViewStateEncryption-Mode property of the Page directive:
<%@Page ViewStateEncryptionMode=”Auto”>
The developer can set the same attribute in a configuration file:
<configuration xmlns =https://scemas.microsoft.com/.NetConfiguration/v2.0>
<system.web>
<pages viewStateEncryptionMode=”Auto”>
…
</system.web>
</configuration>
Note: Encryption imposes a performance penalty, because the web server will perform the encryption and decryption with each postback. Don’t encrypt view state if you don’t need to do it.