What's the best way of saving sensitive data to a local file in Windows 8? I'm developing a C# application that needs to store oAuth tokens/passwords. I've heard it was common in .NET to encrypt/decrypt data, but I don't have any experience with those mechanics. Is encryption still recommended or necessary given that Windows 8 apps have their own personal/protected storage area similar to Windows Phone?
One more question. Are there performance issues when you encrypt or decrypt each time? Would it be better to write a custom algorithm?