How post an image to Tumblr via their V2 API, inside Unity

Image2Tumblr.cs

using UnityEngine;
using System;
using System.Text;
using System.Collections;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using System.Globalization;
using System.Security.Cryptography;
using System.IO;

public class URLUtils {
	private static string _UnreservedChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_.~";
	public static string URLEncodeBytes(byte[] value, bool encodePercent)
	{
		var osb = new StringBuilder(value.Length * 3);
		for (var x = 0; x < value.Length; x++)
		{
			var b = value[x];


			if( (char)b == '%') {
				osb.Append ("%25");
			} else if ((_UnreservedChars.IndexOf((char)b) == -1) && ((char)b) != '~' && (((char)b) != '%'))
			{
				osb.AppendFormat("%{0:X2}", b);
			}
			else
			{
				osb.Append((char)b);
			}
			
		}
		
		if(encodePercent)	{
			osb = osb.Replace("%", "%25");// Revisit to encode actual %'s
		}
		
		return osb.ToString();
	}
}

public class TumblrOAuth : MonoBehaviour {
	
	private string consumerKey = "";
	private string consumerSecret = "";

	private string accessToken = "";
	private string accessTokenSecret = "";

	void Start () {
		string imagePath = "file://"+Application.dataPath + "/../image.png";
		StartCoroutine(UploadImage("xxxx.tumblr.com", imagePath));
	}

	private static string GenerateTimeStamp()
	{
		// Default implementation of UNIX time of the current UTC time
		TimeSpan ts = DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, 0);
		return Convert.ToInt64(ts.TotalSeconds, CultureInfo.CurrentCulture).ToString(CultureInfo.CurrentCulture);
	}
	
	private static string GenerateNonce()
	{
		// Just a simple implementation of a random number between 123400 and 9999999
		return new System.Random().Next(123400, int.MaxValue).ToString();
	}

	
	IEnumerator UploadImage(string blogAddress, string imagePath) {
		string uri =  string.Format("http://api.tumblr.com/v2/blog/{0}/post",blogAddress);

		// download image
		WWW img = new WWW(imagePath);
		yield return img;


		// signature
		Dictionary<string, string> options = new Dictionary<string, string>();
		
		string timestamp = GenerateTimeStamp();
		string nonce = timestamp+GenerateNonce();
		string method = "POST";

		options.Add("oauth_nonce", nonce);
		options.Add("oauth_timestamp", timestamp);

		var stringBuilder = new StringBuilder();
		
		stringBuilder.Append(method+"&");
		stringBuilder.Append(Uri.EscapeDataString(uri));
		stringBuilder.Append("&");
		
		//the key value pairs have to be sorted by encoded key
		var dictionary = new SortedDictionary<string, string>
		{
			//oauth
			{"oauth_token", accessToken},
			{"oauth_consumer_key", consumerKey},
			{"oauth_timestamp", timestamp},
			{"oauth_nonce", nonce},
			{"oauth_signature_method", "HMAC-SHA1"},
			{"oauth_version", "1.0"},

			// post params
			{"type","photo"},
			{"data[0]",""}
		};


		// encode all params
		foreach (var keyValuePair in dictionary)
		{
			
			byte[] bytesValue = System.Text.Encoding.ASCII.GetBytes(keyValuePair.Value);
			string encodedValue;
			
			if(keyValuePair.Key.IndexOf("data") > -1) {
				// encode image data directly from the image bytes
				// when creating the signature the % must be changed with %25, hence the true param for URLEncodeBytes
	
				encodedValue = URLUtils.URLEncodeBytes(img.bytes, true);
			} else {
				encodedValue = URLUtils.URLEncodeBytes(bytesValue,false);
			}
			
			byte[] bytesKey = System.Text.Encoding.ASCII.GetBytes(keyValuePair.Key);
			string encodedKey = URLUtils.URLEncodeBytes(bytesKey,false);
			
			//append a = between the key and the value and a & after the value
			stringBuilder.Append(string.Format("{0}%3D{1}%26", encodedKey, encodedValue));
		}


		// the holy signature base!
		string signatureBaseString = stringBuilder.ToString().Substring(0, stringBuilder.Length - 3);

		string signatureKey =
			Uri.EscapeDataString(consumerSecret) + "&" +
				Uri.EscapeDataString(accessTokenSecret);
		
		var hmacsha1 = new HMACSHA1(
			System.Text.Encoding.ASCII.GetBytes(signatureKey)
			);
		
		// teh signature string
		string signatureString = Convert.ToBase64String(
			hmacsha1.ComputeHash(
			System.Text.Encoding.ASCII.GetBytes(signatureBaseString)));

		signatureString = Uri.EscapeDataString(signatureString);


		// the authorize header
		string auth =  "OAuth oauth_token=\""+accessToken+"\", oauth_consumer_key=\""+consumerKey+"\", oauth_signature_method=\"HMAC-SHA1\", oauth_timestamp=\""+timestamp+"\", oauth_nonce=\""+nonce+"\", oauth_version=\"1.0\", oauth_signature=\""+signatureString+"\"";


		// the post data
		// we have to build it ourselves, because if we use WWWForm, it will enforce it's own way of
		// encoding the image data, and it will break things

		// we don't change % to %25 when adding the post data
		string imgDataEncoded = URLUtils.URLEncodeBytes(img.bytes, false);

		StringBuilder postData = new StringBuilder();
		postData.Append("data%5B0%5D=");
		postData.Append (imgDataEncoded);
		postData.Append ("&type=photo");


		// send request
		Hashtable headers = new Hashtable();
		headers["Authorization"] = auth;
		headers["Content-type"] = "application/x-www-form-urlencoded";

		WWW web = new WWW(uri, System.Text.Encoding.ASCII.GetBytes(postData.ToString()), headers);
		
		yield return web;
		
		if (!string.IsNullOrEmpty(web.error))
		{
			Debug.Log(string.Format("GetAccessToken - failed. error : {0}", web.error));
		} else {
			Debug.Log (web.text);
		}

	}
}