diff --git a/Piwik.Tracker.Tests/CryptoExtensionsTests.cs b/Piwik.Tracker.Tests/CryptoExtensionsTests.cs
new file mode 100644
index 0000000..032119a
--- /dev/null
+++ b/Piwik.Tracker.Tests/CryptoExtensionsTests.cs
@@ -0,0 +1,23 @@
+using NUnit.Framework;
+
+namespace Piwik.Tracker.Tests
+{
+    [TestFixture]
+    internal class CryptoExtensionsTests
+    {
+        [Test]
+        [TestCase("", "da39a3ee5e6b4b0d3255bfef95601890afd80709")]
+        [TestCase(" ", "b858cb282617fb0956d960215c8e84d1ccf909c6")]
+        [TestCase("1234dsfa", "644977634278d36d5f451961fe19622ab13cec87")]
+        [TestCase("1-2-3-45-6", "5c13bf8b7ff1d43869a7b4246bef897f9499833b")]
+        [TestCase("öüüä%&&", "c24eb4685cd57f32098b33066b5b08b31e378981")]
+        [TestCase("+- fdgsdgafdgffdsfddgdgdfdfgdfhdghdfghdgfhgfdgar^^°gfra7685&%§$\"$§&(=)(&=,// \\", "bde6cf181dd5bc0ef11342d5c6a4e81a934d9cb8")]
+        public void ToSha1_RegressionTests(string valueToEncrypt, string expectedHash)
+        {
+            //Act
+            var actualHash = valueToEncrypt.ToSha1();
+            //Assert
+            Assert.That(actualHash, Is.EqualTo(expectedHash));
+        }
+    }
+}
\ No newline at end of file
diff --git a/Piwik.Tracker.Tests/Piwik.Tracker.Tests.csproj b/Piwik.Tracker.Tests/Piwik.Tracker.Tests.csproj
index 2a05905..07ccdb3 100644
--- a/Piwik.Tracker.Tests/Piwik.Tracker.Tests.csproj
+++ b/Piwik.Tracker.Tests/Piwik.Tracker.Tests.csproj
@@ -84,6 +84,7 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="CryptoExtensionsTests.cs" />
     <Compile Include="PiwikTrackerTests.cs" />
     <Compile Include="PiwikTrackerWithMockedServerTests.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
diff --git a/Piwik.Tracker/CryptoExtensions.cs b/Piwik.Tracker/CryptoExtensions.cs
new file mode 100644
index 0000000..87dd984
--- /dev/null
+++ b/Piwik.Tracker/CryptoExtensions.cs
@@ -0,0 +1,47 @@
+using System;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace Piwik.Tracker
+{
+    internal static class CryptoExtensions
+    {
+        /// <summary>
+        /// Creates a sha1 hash from given <paramref name="valueToEncrypt" />.
+        /// </summary>
+        /// <param name="valueToEncrypt">The value to encrypt.</param>
+        /// <returns></returns>
+        public static string ToSha1(this string valueToEncrypt)
+        {
+            if (valueToEncrypt == null)
+            {
+                throw new ArgumentNullException(nameof(valueToEncrypt));
+            }
+            return Encoding.UTF8.GetBytes(valueToEncrypt).ToSha1();
+        }
+
+        /// <summary>
+        /// Creates a sha1 hash from given <paramref name="valueToEncrypt" />.
+        /// </summary>
+        /// <param name="valueToEncrypt">The value to encrypt.</param>
+        /// <returns></returns>
+        public static string ToSha1(this byte[] valueToEncrypt)
+        {
+            if (valueToEncrypt == null)
+            {
+                throw new ArgumentNullException(nameof(valueToEncrypt));
+            }
+            using (var provider = new SHA1CryptoServiceProvider())
+            {
+                var encodedBytes = provider.ComputeHash(valueToEncrypt);
+                var sb = new StringBuilder();
+                foreach (byte b in encodedBytes)
+                {
+                    var hex = b.ToString("x2");
+                    sb.Append(hex);
+                }
+                return sb.ToString();
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/Piwik.Tracker/Piwik.Tracker.csproj b/Piwik.Tracker/Piwik.Tracker.csproj
index 2c152b9..9ab6c6d 100644
--- a/Piwik.Tracker/Piwik.Tracker.csproj
+++ b/Piwik.Tracker/Piwik.Tracker.csproj
@@ -46,6 +46,7 @@
   <ItemGroup>
     <Compile Include="AttributionInfo.cs" />
     <Compile Include="BrowserPlugins.cs" />
+    <Compile Include="CryptoExtensions.cs" />
     <Compile Include="CustomVar.cs" />
     <Compile Include="Enums.cs" />
     <Compile Include="PiwikTracker.cs" />
diff --git a/Piwik.Tracker/PiwikTracker.cs b/Piwik.Tracker/PiwikTracker.cs
index 0f6d0fb..5ebe865 100644
--- a/Piwik.Tracker/PiwikTracker.cs
+++ b/Piwik.Tracker/PiwikTracker.cs
@@ -17,8 +17,6 @@ namespace Piwik.Tracker
     using System.Linq;
     using System.Net;
     using System.Globalization;
-    using System.Text;
-    using System.Security.Cryptography;
     using System.Web;
     using System.Web.Script.Serialization;
     using System.Text.RegularExpressions;
@@ -431,8 +429,7 @@ public void ClearCustomTrackingParameters()
         /// </summary>
         public void SetNewVisitorId()
         {
-            var encodedGuidBytes = new MD5CryptoServiceProvider().ComputeHash(Encoding.Default.GetBytes(Guid.NewGuid().ToString()));
-            _randomVisitorId = BitConverter.ToString(encodedGuidBytes).Replace("-", "").Substring(0, LengthVisitorId).ToLower();
+            _randomVisitorId = Guid.NewGuid().ToByteArray().ToSha1().Substring(0, LengthVisitorId);
             _userId = null;
             _forcedVisitorId = null;
             _cookieVisitorId = null;
@@ -575,26 +572,14 @@ protected static string DomainFixup(string domain)
         protected string GetCookieName(string cookieName)
         {
             // NOTE: If the cookie name is changed, we must also update the method in piwik.js with the same name.
-            var hash = GetHexStringFromBytes(new SHA1CryptoServiceProvider().ComputeHash(Encoding.UTF8.GetBytes((string.IsNullOrWhiteSpace(_configCookieDomain) ? GetCurrentHost() : _configCookieDomain) + _configCookiePath))).Substring(0, 4);
+            var cookieDomain = (string.IsNullOrWhiteSpace(_configCookieDomain)
+                ? GetCurrentHost()
+                : _configCookieDomain)
+                + _configCookiePath;
+            var hash = cookieDomain.ToSha1().Substring(0, 4);
             return FirstPartyCookiesPrefix + cookieName + "." + IdSite + "." + hash;
         }
 
-        /// <summary>
-        /// Gets the hexadecimal string from bytes.
-        /// </summary>
-        /// <param name="bytes">The bytes.</param>
-        /// <returns></returns>
-        protected static string GetHexStringFromBytes(byte[] bytes)
-        {
-            var sb = new StringBuilder();
-            foreach (byte b in bytes)
-            {
-                var hex = b.ToString("x2");
-                sb.Append(hex);
-            }
-            return sb.ToString();
-        }
-
         /// <summary>
         /// Tracks a page view
         /// </summary>
@@ -1177,8 +1162,8 @@ public void SetUserId(string userId)
         /// <returns></returns>
         public static string GetUserIdHashed(string id)
         {
-            var encodedIdBytes = new SHA1CryptoServiceProvider().ComputeHash(Encoding.Default.GetBytes(id));
-            return BitConverter.ToString(encodedIdBytes).Substring(0, 16);
+            var hash = (id ?? string.Empty).ToSha1();
+            return hash.Substring(0, 16);
         }
 
         /// <summary>