I was working with porting the sample from the link below to a Windows 8 Metro styled app

<http://aws.amazon.com/code/Product-Advertising-API/2480>

Looks like many features from the web model are removed (or moved) in WinRT:

```
HttpUtility.UrlEncode
HttpUtility.UrlDecode
HMAC / HMACSHA256 

```

to name a few, I was wondering if anyone could help with finding alternatives to these on WInRT? I looked online and there's very little insight.