OAuth-WinRT

A quick sample demonstrating migrating a simple .NET library to Windows Runtime.

This is the original source: http://oauth.googlecode.com/svn/code/csharp/OAuthBase.cs.

Notable changes

Cryptography API Changes

These are a little bit more verbose now...

Setting up the hash algorithm

Before:

HMACSHA1 hmacsha1 = new HMACSHA1();
hmacsha1.Key = Encoding.ASCII.GetBytes(string.Format("{0}&{1}", UrlEncode(consumerSecret), string.IsNullOrEmpty(tokenSecret) ? "" : UrlEncode(tokenSecret)));

After:

var algorithm = MacAlgorithmProvider.OpenAlgorithm(MacAlgorithmNames.HmacSha1);
var value = string.Format("{0}&{1}", UrlEncode(consumerSecret), string.IsNullOrEmpty(tokenSecret) ? "" : UrlEncode(tokenSecret));

var keymaterial = CryptographicBuffer.ConvertStringToBinary(value, BinaryStringEncoding.Utf8);
var hmacKey = algorithm.CreateKey(keymaterial);

Computing the hash

Before:

byte[] dataBuffer = System.Text.Encoding.ASCII.GetBytes(data);
byte[] hashBytes = hashAlgorithm.ComputeHash(dataBuffer);

return Convert.ToBase64String(hashBytes);

After:

var signature = CryptographicEngine.Sign(
            hashAlgorithm,
            CryptographicBuffer.ConvertStringToBinary(data, BinaryStringEncoding.Utf8));

return signature;

Working with Streams

Windows.Storage.Streams.IBuffer is a new interface to represent an array of bytes. This gets used in much of the cryptography APIs (pass in a buffer, receieve a buffer) rather than working with primitive structures.

Its actually very plain:

public interface IBuffer
{
    uint Capacity { get; }
    uint Length { get; set; }
}

I need to do some more digging into this class, I'm sure there's more to it than this...

Access Modifiers

No public fields allowed

This requires some notes on how the Windows Runtime type system works...

protected and virtual are frowned upon

Consider a class which is intended to be overriden:

protected class QueryParameter
{
    public QueryParameter(string key, string value)
    {
        Name = key;
        Value = val;
    }

    ...
}

This will raise a compiler error:

Elements defined in a namespace cannot be explicitly declared as private, protected, or protected internal

And the fix for that is fairly easy:

internal class QueryParameter
{
    public QueryParameter(string key, string value)
    {
        Name = key;
        Value = val;
    }

    ...
}

public classes must be sealed

public class QueryParameter
{
    public QueryParameter(string key, string value)
    {
        Name = key;
        Value = val;
    }

    ...
}

This code raises a compiler error:

Exporting unsealed types is not supported. Please mark type 'OAuth.QueryParameter' as sealed.

And the fix for that is fairly easy:

public sealed class QueryParameter
{
    public QueryParameter(string key, string value)
    {
        Name = key;
        Value = val;
    }

    ...
}

TODO: other samples

"value" is a dirty word

This code was valid before:

public sealed class QueryParameter
{
    public QueryParameter(string key, string value)
    {
        Name = key;
        Value = val;
    }

    ...
}

But now it spits out a compiler error in RTM:

The parameterized constructor 'OAuth.QueryParameter..ctor(System.String, System.String)' has a parameter named 'value' which is the same as the default return value name. Consider using another name for the parameter.

And the fix is reasonably simple:

public sealed class QueryParameter
{
    public QueryParameter(string key, string val)
    {
        Name = key;
        Value = val;
    }

    ...
}