This tool allows you to generate random keys for validation and ecnryption/decryption of the view state (and other purposes). It builds a <machineKey> element which you need to include in your web.config file.

The tool creates a 256-bit decryption key and a 512-bit validation key, with Rijndael as the data validation algorithm.

Once the keys are generated, they are converted into a string of hexadecimal characters.

For more information about the <machineKey> section, see machineKey Element external link on MSDN.