Data commit

Task/Substitution-cipher/C-sharp/substitution-cipher.cs

@@ -0,0 +1,144 @@
+using System;
+using System.IO;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace SubstitutionCipherProject
+{
+    class SubstitutionCipher
+    {
+        static void Main(string[] args)
+        {
+            doEncDec("e:\\source.txt", "enc.txt", true);
+            doEncDec("enc.txt", "dec.txt", false);
+            Console.WriteLine("Done");
+            Console.ReadKey();
+        }
+        static void doEncDec(String source, String target, bool IsEncrypt)
+        {
+            ITransform trans;
+
+            if (IsEncrypt)
+                trans = new Encrypt();
+            else
+                trans = new Decrypt();
+
+            FileInfo sfi = new FileInfo(source);
+            FileStream sstream = sfi.OpenRead();
+            StreamReader sr = new StreamReader(sstream);
+
+            FileInfo tfi = new FileInfo(target);
+            FileStream tstream = tfi.OpenWrite();
+            TransformWriter tw = new TransformWriter(tstream, trans);
+            StreamWriter sw = new StreamWriter(tw);
+
+            String line;
+            while ((line = sr.ReadLine()) != null)
+                sw.WriteLine(line);
+            sw.Close();
+        }
+    }
+    public interface ITransform
+    {
+        byte transform(byte ch);
+    }
+    public class Encrypt : ITransform
+    {
+        const String str = "xyfagchbimpourvnqsdewtkjzl";
+        byte ITransform.transform(byte ch)
+        {
+            if (char.IsLower((char)ch))
+                ch = (byte)str[ch - (byte)'a'];
+            return ch;
+        }
+    }
+    class Decrypt : ITransform
+    {
+        const String str = "xyfagchbimpourvnqsdewtkjzl";
+        byte ITransform.transform(byte ch)
+        {
+            if (char.IsLower((char)ch))
+                ch = (byte)(str.IndexOf((char)ch) + 'a');
+            return ch;
+        }
+    }
+    class TransformWriter : Stream, IDisposable
+    {
+        private Stream outs;
+        private ITransform trans;
+
+        public TransformWriter(Stream s, ITransform t)
+        {
+            this.outs = s;
+            this.trans = t;
+        }
+
+        public override bool CanRead
+        {
+            get { return false; }
+        }
+
+        public override bool CanSeek
+        {
+            get { return false; }
+        }
+
+        public override bool CanWrite
+        {
+            get { return true; }
+        }
+        public override void Flush()
+        {
+            outs.Flush();
+        }
+
+        public override long Length
+        {
+            get { return outs.Length; }
+        }
+        public override long Position
+        {
+            get
+            {
+                return outs.Position;
+            }
+            set
+            {
+                outs.Position = value;
+            }
+        }
+        public override long Seek(long offset, SeekOrigin origin)
+        {
+            return outs.Seek(offset, origin);
+        }
+
+        public override void SetLength(long value)
+        {
+            outs.SetLength(value);
+        }
+
+        public override void Write(byte[] buf, int off, int len)
+        {
+            for (int i = off; i < off + len; i++)
+                buf[i] = trans.transform(buf[i]);
+            outs.Write(buf, off, len);
+        }
+
+        void IDisposable.Dispose()
+        {
+            outs.Dispose();
+        }
+
+        public override void Close()
+        {
+            outs.Close();
+        }
+
+        public override int Read(byte[] cbuf, int off, int count)
+        {
+            return outs.Read(cbuf, off, count);
+        }
+    }
+}