Basic implementation of the Booli API rest-service using C#

booli.cs

using RestSharp;
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Security.Cryptography;
using System.Text;

namespace api.Services
{
    public class BooliServices
    {
	readonly string key = "YOUR-API-KEY";
	readonly string callerId = "YOUR-CALLER-ID";
	readonly string refererUrl = "YOUR-REFERER-URL";
	    
        public IRestResponse GetBooliProperties(string requestQuery, int? requestOffset, string objectType)
        {
	    //CREATE YOUR MODEL TO DESERIALIZE THE JSON-RESPONSE
            var Json = new BooliPropertyListing();

            var timestamp = UnixTimestamp();
            var unique = Unique16();

	    var hash = HashFactory.createHash(stringToHash(timestamp, unique, callerId));
            int requestLimit = 400;
            var requestClient = new RestClient("https://api.booli.se/");
            var Request = new RestRequest("listings?bbox=" + requestQuery + "&objectType=" + objectType + "&limit=" + requestLimit + "&offset=" + requestOffset + "&callerId=" + callerId + "&time=" + timestamp + "&unique=" + unique + "&hash=" + hash, Method.GET);
            Request.AddHeader("Referer", refererUrl);
            return requestClient.Execute<BooliPropertyListing>(Request);
        }

        private int UnixTimestamp()
        {
            Int32 unixTimestamp = (Int32)(DateTime.UtcNow.Subtract(new DateTime(1970, 1, 1))).TotalSeconds;
            return unixTimestamp;
        }

        private string Unique16()
        {
            var chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
            var stringChars = new char[16];
            var random = new Random();

            for (int i = 0; i < stringChars.Length; i++)
            {
                stringChars[i] = chars[random.Next(chars.Length)];
            }

            return new String(stringChars);
        }

        private string stringToHash(int timestamp, string unique, string callerId)
        {
            return string.Format("{0}{1}{2}{3}",callerId,timestamp,key,unique);
        }

        public static class HashFactory
        {
            public static string createHash(string s)
            {
                byte[] bytes = Encoding.UTF8.GetBytes(s);

                var sha1 = SHA1.Create();
                byte[] hashBytes = sha1.ComputeHash(bytes);

                return HexStringFromBytes(hashBytes);
            }

            public static string HexStringFromBytes(byte[] bytes)
            {
                var sb = new StringBuilder();
                foreach (byte b in bytes)
                {
                    var hex = b.ToString("x2");
                    sb.Append(hex);
                }
                return sb.ToString();
            }
        }
	}
	
}