diff --git a/Adler32Context.cs b/Adler32Context.cs
index a950b84..1723bcd 100644
--- a/Adler32Context.cs
+++ b/Adler32Context.cs
@@ -119,11 +119,9 @@ namespace DiscImageChef.Checksums
         public static string File(string filename, out byte[] hash)
         {
             FileStream fileStream = new FileStream(filename, FileMode.Open);
-            ushort     localSum1, localSum2;
-            uint       finalSum;
 
-            localSum1 = 1;
-            localSum2 = 0;
+            ushort localSum1 = 1;
+            ushort localSum2 = 0;
 
             for(int i = 0; i < fileStream.Length; i++)
             {
@@ -131,7 +129,7 @@ namespace DiscImageChef.Checksums
                 localSum2 = (ushort)((localSum2 + localSum1)             % ADLER_MODULE);
             }
 
-            finalSum = (uint)((localSum2 << 16) | localSum1);
+            uint finalSum = (uint)((localSum2 << 16) | localSum1);
 
             BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;
             hash                                 = BigEndianBitConverter.GetBytes(finalSum);
@@ -153,11 +151,8 @@ namespace DiscImageChef.Checksums
         /// <param name="hash">Byte array of the hash value.</param>
         public static string Data(byte[] data, uint len, out byte[] hash)
         {
-            ushort localSum1, localSum2;
-            uint   finalSum;
-
-            localSum1 = 1;
-            localSum2 = 0;
+            ushort localSum1 = 1;
+            ushort localSum2 = 0;
 
             for(int i = 0; i < len; i++)
             {
@@ -165,7 +160,7 @@ namespace DiscImageChef.Checksums
                 localSum2 = (ushort)((localSum2 + localSum1) % ADLER_MODULE);
             }
 
-            finalSum = (uint)((localSum2 << 16) | localSum1);
+            uint finalSum = (uint)((localSum2 << 16) | localSum1);
 
             BigEndianBitConverter.IsLittleEndian = BitConverter.IsLittleEndian;
             hash                                 = BigEndianBitConverter.GetBytes(finalSum);
diff --git a/CRC32Context.cs b/CRC32Context.cs
index e5c9bc3..6245815 100644
--- a/CRC32Context.cs
+++ b/CRC32Context.cs
@@ -217,9 +217,7 @@ namespace DiscImageChef.Checksums
         /// <param name="seed">CRC seed</param>
         public static string Data(byte[] data, uint len, out byte[] hash, uint polynomial, uint seed)
         {
-            uint localhashInt;
-
-            localhashInt = seed;
+            uint localhashInt = seed;
 
             uint[] localTable = new uint[256];
             for(int i = 0; i < 256; i++)
diff --git a/FletcherContext.cs b/FletcherContext.cs
index f8eb3f7..0c1edf9 100644
--- a/FletcherContext.cs
+++ b/FletcherContext.cs
@@ -173,12 +173,11 @@ namespace DiscImageChef.Checksums
         public static string File(string filename, out byte[] hash)
         {
             FileStream fileStream = new FileStream(filename, FileMode.Open);
-            ushort     localSum1, localSum2, block;
-            uint       finalSum;
+            ushort     block;
             byte[]     blockBytes;
 
-            localSum1 = 0xFFFF;
-            localSum2 = 0xFFFF;
+            ushort localSum1 = 0xFFFF;
+            ushort localSum2 = 0xFFFF;
 
             if(fileStream.Length % 2 == 0)
                 for(int i = 0; i     < fileStream.Length; i += 2)
@@ -209,7 +208,7 @@ namespace DiscImageChef.Checksums
                 localSum2 = (ushort)((localSum2 + localSum1) % 0xFFFF);
             }
 
-            finalSum = (uint)(localSum1 + (localSum2 << 16));
+            uint finalSum = (uint)(localSum1 + (localSum2 << 16));
 
             hash = BitConverter.GetBytes(finalSum);
 
@@ -228,11 +227,10 @@ namespace DiscImageChef.Checksums
         /// <param name="hash">Byte array of the hash value.</param>
         public static string Data(byte[] data, uint len, out byte[] hash)
         {
-            ushort localSum1, localSum2, block;
-            uint   finalSum;
+            ushort block;
 
-            localSum1 = 0xFFFF;
-            localSum2 = 0xFFFF;
+            ushort localSum1 = 0xFFFF;
+            ushort localSum2 = 0xFFFF;
 
             if(len % 2           == 0)
                 for(int i = 0; i < len; i += 2)
@@ -259,7 +257,7 @@ namespace DiscImageChef.Checksums
                 localSum2 = (ushort)((localSum2 + localSum1) % 0xFFFF);
             }
 
-            finalSum = (uint)(localSum1 + (localSum2 << 16));
+            uint finalSum = (uint)(localSum1 + (localSum2 << 16));
 
             hash = BitConverter.GetBytes(finalSum);
 
@@ -281,14 +279,14 @@ namespace DiscImageChef.Checksums
         }
     }
 
-    public class Fletcher16Context
+    public class Fletcher16Context : IChecksum
     {
         byte sum1, sum2;
 
         /// <summary>
         ///     Initializes the Fletcher16 sums
         /// </summary>
-        public void Init()
+        public Fletcher16Context()
         {
             sum1 = 0xFF;
             sum2 = 0xFF;
@@ -358,20 +356,18 @@ namespace DiscImageChef.Checksums
         public static string File(string filename, out byte[] hash)
         {
             FileStream fileStream = new FileStream(filename, FileMode.Open);
-            byte       localSum1, localSum2, block;
-            ushort     finalSum;
 
-            localSum1 = 0xFF;
-            localSum2 = 0xFF;
+            byte localSum1 = 0xFF;
+            byte localSum2 = 0xFF;
 
             for(int i = 0; i < fileStream.Length; i += 2)
             {
-                block     = (byte)fileStream.ReadByte();
-                localSum1 = (byte)((localSum1 + block)     % 0xFF);
-                localSum2 = (byte)((localSum2 + localSum1) % 0xFF);
+                byte block = (byte)fileStream.ReadByte();
+                localSum1  = (byte)((localSum1 + block)     % 0xFF);
+                localSum2  = (byte)((localSum2 + localSum1) % 0xFF);
             }
 
-            finalSum = (ushort)(localSum1 + (localSum2 << 8));
+            ushort finalSum = (ushort)(localSum1 + (localSum2 << 8));
 
             hash = BitConverter.GetBytes(finalSum);
 
@@ -390,11 +386,8 @@ namespace DiscImageChef.Checksums
         /// <param name="hash">Byte array of the hash value.</param>
         public static string Data(byte[] data, uint len, out byte[] hash)
         {
-            byte   localSum1, localSum2;
-            ushort finalSum;
-
-            localSum1 = 0xFF;
-            localSum2 = 0xFF;
+            byte localSum1 = 0xFF;
+            byte localSum2 = 0xFF;
 
             for(int i = 0; i < len; i++)
             {
@@ -402,7 +395,7 @@ namespace DiscImageChef.Checksums
                 localSum2 = (byte)((localSum2 + localSum1) % 0xFF);
             }
 
-            finalSum = (ushort)(localSum1 + (localSum2 << 8));
+            ushort finalSum = (ushort)(localSum1 + (localSum2 << 8));
 
             hash = BitConverter.GetBytes(finalSum);
 
diff --git a/MD5Context.cs b/MD5Context.cs
index 90a9c5b..0ef1555 100644
--- a/MD5Context.cs
+++ b/MD5Context.cs
@@ -96,10 +96,11 @@ namespace DiscImageChef.Checksums
         ///     Gets the hash of a file
         /// </summary>
         /// <param name="filename">File path.</param>
-        public byte[] File(string filename)
+        public static byte[] File(string filename)
         {
-            FileStream fileStream = new FileStream(filename, FileMode.Open);
-            byte[]     result     = md5Provider.ComputeHash(fileStream);
+            MD5        localMd5Provider = MD5.Create();
+            FileStream fileStream       = new FileStream(filename, FileMode.Open);
+            byte[]     result           = localMd5Provider.ComputeHash(fileStream);
             fileStream.Close();
             return result;
         }
@@ -109,11 +110,12 @@ namespace DiscImageChef.Checksums
         /// </summary>
         /// <param name="filename">File path.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string File(string filename, out byte[] hash)
+        public static string File(string filename, out byte[] hash)
         {
-            FileStream fileStream   = new FileStream(filename, FileMode.Open);
-            hash                    = md5Provider.ComputeHash(fileStream);
-            StringBuilder md5Output = new StringBuilder();
+            MD5        localMd5Provider = MD5.Create();
+            FileStream fileStream       = new FileStream(filename, FileMode.Open);
+            hash                        = localMd5Provider.ComputeHash(fileStream);
+            StringBuilder md5Output     = new StringBuilder();
 
             foreach(byte h in hash) md5Output.Append(h.ToString("x2"));
 
@@ -128,9 +130,10 @@ namespace DiscImageChef.Checksums
         /// <param name="data">Data buffer.</param>
         /// <param name="len">Length of the data buffer to hash.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string Data(byte[] data, uint len, out byte[] hash)
+        public static string Data(byte[] data, uint len, out byte[] hash)
         {
-            hash                    = md5Provider.ComputeHash(data, 0, (int)len);
+            MD5 localMd5Provider    = MD5.Create();
+            hash                    = localMd5Provider.ComputeHash(data, 0, (int)len);
             StringBuilder md5Output = new StringBuilder();
 
             foreach(byte h in hash) md5Output.Append(h.ToString("x2"));
@@ -143,7 +146,7 @@ namespace DiscImageChef.Checksums
         /// </summary>
         /// <param name="data">Data buffer.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string Data(byte[] data, out byte[] hash)
+        public static string Data(byte[] data, out byte[] hash)
         {
             return Data(data, (uint)data.Length, out hash);
         }
diff --git a/RIPEMD160Context.cs b/RIPEMD160Context.cs
index 404f9e3..0c40046 100644
--- a/RIPEMD160Context.cs
+++ b/RIPEMD160Context.cs
@@ -96,10 +96,11 @@ namespace DiscImageChef.Checksums
         ///     Gets the hash of a file
         /// </summary>
         /// <param name="filename">File path.</param>
-        public byte[] File(string filename)
+        public static byte[] File(string filename)
         {
-            FileStream fileStream = new FileStream(filename, FileMode.Open);
-            byte[]     result     = ripemd160Provider.ComputeHash(fileStream);
+            RIPEMD160  localRipemd160Provider = RIPEMD160.Create();
+            FileStream fileStream             = new FileStream(filename, FileMode.Open);
+            byte[]     result                 = localRipemd160Provider.ComputeHash(fileStream);
             fileStream.Close();
             return result;
         }
@@ -109,11 +110,12 @@ namespace DiscImageChef.Checksums
         /// </summary>
         /// <param name="filename">File path.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string File(string filename, out byte[] hash)
+        public static string File(string filename, out byte[] hash)
         {
-            FileStream fileStream         = new FileStream(filename, FileMode.Open);
-            hash                          = ripemd160Provider.ComputeHash(fileStream);
-            StringBuilder ripemd160Output = new StringBuilder();
+            RIPEMD160  localRipemd160Provider = RIPEMD160.Create();
+            FileStream fileStream             = new FileStream(filename, FileMode.Open);
+            hash                              = localRipemd160Provider.ComputeHash(fileStream);
+            StringBuilder ripemd160Output     = new StringBuilder();
 
             foreach(byte h in hash) ripemd160Output.Append(h.ToString("x2"));
 
@@ -128,10 +130,11 @@ namespace DiscImageChef.Checksums
         /// <param name="data">Data buffer.</param>
         /// <param name="len">Length of the data buffer to hash.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string Data(byte[] data, uint len, out byte[] hash)
+        public static string Data(byte[] data, uint len, out byte[] hash)
         {
-            hash                          = ripemd160Provider.ComputeHash(data, 0, (int)len);
-            StringBuilder ripemd160Output = new StringBuilder();
+            RIPEMD160 localRipemd160Provider = RIPEMD160.Create();
+            hash                             = localRipemd160Provider.ComputeHash(data, 0, (int)len);
+            StringBuilder ripemd160Output    = new StringBuilder();
 
             foreach(byte h in hash) ripemd160Output.Append(h.ToString("x2"));
 
@@ -143,7 +146,7 @@ namespace DiscImageChef.Checksums
         /// </summary>
         /// <param name="data">Data buffer.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string Data(byte[] data, out byte[] hash)
+        public static string Data(byte[] data, out byte[] hash)
         {
             return Data(data, (uint)data.Length, out hash);
         }
diff --git a/SHA1Context.cs b/SHA1Context.cs
index 23c5cc8..c232d36 100644
--- a/SHA1Context.cs
+++ b/SHA1Context.cs
@@ -96,10 +96,11 @@ namespace DiscImageChef.Checksums
         ///     Gets the hash of a file
         /// </summary>
         /// <param name="filename">File path.</param>
-        public byte[] File(string filename)
+        public static byte[] File(string filename)
         {
-            FileStream fileStream = new FileStream(filename, FileMode.Open);
-            byte[]     result     = sha1Provider.ComputeHash(fileStream);
+            SHA1       localSha1Provider = SHA1.Create();
+            FileStream fileStream        = new FileStream(filename, FileMode.Open);
+            byte[]     result            = localSha1Provider.ComputeHash(fileStream);
             fileStream.Close();
             return result;
         }
@@ -109,11 +110,12 @@ namespace DiscImageChef.Checksums
         /// </summary>
         /// <param name="filename">File path.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string File(string filename, out byte[] hash)
+        public static string File(string filename, out byte[] hash)
         {
-            FileStream fileStream    = new FileStream(filename, FileMode.Open);
-            hash                     = sha1Provider.ComputeHash(fileStream);
-            StringBuilder sha1Output = new StringBuilder();
+            SHA1       localSha1Provider = SHA1.Create();
+            FileStream fileStream        = new FileStream(filename, FileMode.Open);
+            hash                         = localSha1Provider.ComputeHash(fileStream);
+            StringBuilder sha1Output     = new StringBuilder();
 
             foreach(byte h in hash) sha1Output.Append(h.ToString("x2"));
 
@@ -128,9 +130,10 @@ namespace DiscImageChef.Checksums
         /// <param name="data">Data buffer.</param>
         /// <param name="len">Length of the data buffer to hash.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string Data(byte[] data, uint len, out byte[] hash)
+        public static string Data(byte[] data, uint len, out byte[] hash)
         {
-            hash                     = sha1Provider.ComputeHash(data, 0, (int)len);
+            SHA1 localSha1Provider   = SHA1.Create();
+            hash                     = localSha1Provider.ComputeHash(data, 0, (int)len);
             StringBuilder sha1Output = new StringBuilder();
 
             foreach(byte h in hash) sha1Output.Append(h.ToString("x2"));
@@ -143,7 +146,7 @@ namespace DiscImageChef.Checksums
         /// </summary>
         /// <param name="data">Data buffer.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string Data(byte[] data, out byte[] hash)
+        public static string Data(byte[] data, out byte[] hash)
         {
             return Data(data, (uint)data.Length, out hash);
         }
diff --git a/SHA256Context.cs b/SHA256Context.cs
index e0056fb..f2e6142 100644
--- a/SHA256Context.cs
+++ b/SHA256Context.cs
@@ -96,10 +96,11 @@ namespace DiscImageChef.Checksums
         ///     Gets the hash of a file
         /// </summary>
         /// <param name="filename">File path.</param>
-        public byte[] File(string filename)
+        public static byte[] File(string filename)
         {
-            FileStream fileStream = new FileStream(filename, FileMode.Open);
-            byte[]     result     = sha256Provider.ComputeHash(fileStream);
+            SHA256     localSha256Provider = SHA256.Create();
+            FileStream fileStream          = new FileStream(filename, FileMode.Open);
+            byte[]     result              = localSha256Provider.ComputeHash(fileStream);
             fileStream.Close();
             return result;
         }
@@ -109,11 +110,12 @@ namespace DiscImageChef.Checksums
         /// </summary>
         /// <param name="filename">File path.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string File(string filename, out byte[] hash)
+        public static string File(string filename, out byte[] hash)
         {
-            FileStream fileStream      = new FileStream(filename, FileMode.Open);
-            hash                       = sha256Provider.ComputeHash(fileStream);
-            StringBuilder sha256Output = new StringBuilder();
+            SHA256     localSha256Provider = SHA256.Create();
+            FileStream fileStream          = new FileStream(filename, FileMode.Open);
+            hash                           = localSha256Provider.ComputeHash(fileStream);
+            StringBuilder sha256Output     = new StringBuilder();
 
             foreach(byte h in hash) sha256Output.Append(h.ToString("x2"));
 
@@ -128,9 +130,10 @@ namespace DiscImageChef.Checksums
         /// <param name="data">Data buffer.</param>
         /// <param name="len">Length of the data buffer to hash.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string Data(byte[] data, uint len, out byte[] hash)
+        public static string Data(byte[] data, uint len, out byte[] hash)
         {
-            hash                       = sha256Provider.ComputeHash(data, 0, (int)len);
+            SHA256 localSha256Provider = SHA256.Create();
+            hash                       = localSha256Provider.ComputeHash(data, 0, (int)len);
             StringBuilder sha256Output = new StringBuilder();
 
             foreach(byte h in hash) sha256Output.Append(h.ToString("x2"));
@@ -143,7 +146,7 @@ namespace DiscImageChef.Checksums
         /// </summary>
         /// <param name="data">Data buffer.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string Data(byte[] data, out byte[] hash)
+        public static string Data(byte[] data, out byte[] hash)
         {
             return Data(data, (uint)data.Length, out hash);
         }
diff --git a/SHA384Context.cs b/SHA384Context.cs
index cd66c8b..7e669c5 100644
--- a/SHA384Context.cs
+++ b/SHA384Context.cs
@@ -96,10 +96,11 @@ namespace DiscImageChef.Checksums
         ///     Gets the hash of a file
         /// </summary>
         /// <param name="filename">File path.</param>
-        public byte[] File(string filename)
+        public static byte[] File(string filename)
         {
-            FileStream fileStream = new FileStream(filename, FileMode.Open);
-            byte[]     result     = sha384Provider.ComputeHash(fileStream);
+            SHA384     localSha384Provider = SHA384.Create();
+            FileStream fileStream          = new FileStream(filename, FileMode.Open);
+            byte[]     result              = localSha384Provider.ComputeHash(fileStream);
             fileStream.Close();
             return result;
         }
@@ -109,11 +110,12 @@ namespace DiscImageChef.Checksums
         /// </summary>
         /// <param name="filename">File path.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string File(string filename, out byte[] hash)
+        public static string File(string filename, out byte[] hash)
         {
-            FileStream fileStream      = new FileStream(filename, FileMode.Open);
-            hash                       = sha384Provider.ComputeHash(fileStream);
-            StringBuilder sha384Output = new StringBuilder();
+            SHA384     localSha384Provider = SHA384.Create();
+            FileStream fileStream          = new FileStream(filename, FileMode.Open);
+            hash                           = localSha384Provider.ComputeHash(fileStream);
+            StringBuilder sha384Output     = new StringBuilder();
 
             foreach(byte h in hash) sha384Output.Append(h.ToString("x2"));
 
@@ -128,9 +130,10 @@ namespace DiscImageChef.Checksums
         /// <param name="data">Data buffer.</param>
         /// <param name="len">Length of the data buffer to hash.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string Data(byte[] data, uint len, out byte[] hash)
+        public static string Data(byte[] data, uint len, out byte[] hash)
         {
-            hash                       = sha384Provider.ComputeHash(data, 0, (int)len);
+            SHA384 localSha384Provider = SHA384.Create();
+            hash                       = localSha384Provider.ComputeHash(data, 0, (int)len);
             StringBuilder sha384Output = new StringBuilder();
 
             foreach(byte h in hash) sha384Output.Append(h.ToString("x2"));
@@ -143,7 +146,7 @@ namespace DiscImageChef.Checksums
         /// </summary>
         /// <param name="data">Data buffer.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string Data(byte[] data, out byte[] hash)
+        public static string Data(byte[] data, out byte[] hash)
         {
             return Data(data, (uint)data.Length, out hash);
         }
diff --git a/SHA512Context.cs b/SHA512Context.cs
index d90e0ff..2a9a4df 100644
--- a/SHA512Context.cs
+++ b/SHA512Context.cs
@@ -96,10 +96,11 @@ namespace DiscImageChef.Checksums
         ///     Gets the hash of a file
         /// </summary>
         /// <param name="filename">File path.</param>
-        public byte[] File(string filename)
+        public static byte[] File(string filename)
         {
-            FileStream fileStream = new FileStream(filename, FileMode.Open);
-            byte[]     result     = sha512Provider.ComputeHash(fileStream);
+            SHA512     localSha512Provider = SHA512.Create();
+            FileStream fileStream          = new FileStream(filename, FileMode.Open);
+            byte[]     result              = localSha512Provider.ComputeHash(fileStream);
             fileStream.Close();
             return result;
         }
@@ -109,11 +110,12 @@ namespace DiscImageChef.Checksums
         /// </summary>
         /// <param name="filename">File path.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string File(string filename, out byte[] hash)
+        public static string File(string filename, out byte[] hash)
         {
-            FileStream fileStream      = new FileStream(filename, FileMode.Open);
-            hash                       = sha512Provider.ComputeHash(fileStream);
-            StringBuilder sha512Output = new StringBuilder();
+            SHA512     localSha512Provider = SHA512.Create();
+            FileStream fileStream          = new FileStream(filename, FileMode.Open);
+            hash                           = localSha512Provider.ComputeHash(fileStream);
+            StringBuilder sha512Output     = new StringBuilder();
 
             foreach(byte h in hash) sha512Output.Append(h.ToString("x2"));
 
@@ -128,9 +130,10 @@ namespace DiscImageChef.Checksums
         /// <param name="data">Data buffer.</param>
         /// <param name="len">Length of the data buffer to hash.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string Data(byte[] data, uint len, out byte[] hash)
+        public static string Data(byte[] data, uint len, out byte[] hash)
         {
-            hash                       = sha512Provider.ComputeHash(data, 0, (int)len);
+            SHA512 localSha512Provider = SHA512.Create();
+            hash                       = localSha512Provider.ComputeHash(data, 0, (int)len);
             StringBuilder sha512Output = new StringBuilder();
 
             foreach(byte h in hash) sha512Output.Append(h.ToString("x2"));
@@ -143,7 +146,7 @@ namespace DiscImageChef.Checksums
         /// </summary>
         /// <param name="data">Data buffer.</param>
         /// <param name="hash">Byte array of the hash value.</param>
-        public string Data(byte[] data, out byte[] hash)
+        public static string Data(byte[] data, out byte[] hash)
         {
             return Data(data, (uint)data.Length, out hash);
         }