Initial Commit

iTechSharp/srcbc/crypto/paddings/Pkcs7Padding.cs

@@ -0,0 +1,77 @@
+using System;
+using Org.BouncyCastle.Crypto;
+using Org.BouncyCastle.Security;
+
+
+namespace Org.BouncyCastle.Crypto.Paddings
+{
+    /**
+    * A padder that adds Pkcs7/Pkcs5 padding to a block.
+    */
+    public class Pkcs7Padding: IBlockCipherPadding
+    {
+        /**
+        * Initialise the padder.
+        *
+        * @param random - a SecureRandom if available.
+        */
+        public void Init(SecureRandom random)
+        {
+            // nothing to do.
+        }
+
+        /**
+        * Return the name of the algorithm the cipher implements.
+        *
+        * @return the name of the algorithm the cipher implements.
+        */
+        public string PaddingName
+        {
+            get { return "PKCS7"; }
+        }
+
+		/**
+        * add the pad bytes to the passed in block, returning the
+        * number of bytes added.
+        */
+        public int AddPadding(
+            byte[]  input,
+            int     inOff)
+        {
+            byte code = (byte)(input.Length - inOff);
+
+            while (inOff < input.Length)
+            {
+                input[inOff] = code;
+                inOff++;
+            }
+
+            return code;
+        }
+
+        /**
+        * return the number of pad bytes present in the block.
+        */
+        public int PadCount(
+			byte[] input)
+        {
+            int count = (int) input[input.Length - 1];
+
+			if (count < 1 || count > input.Length)
+            {
+                throw new InvalidCipherTextException("pad block corrupted");
+            }
+
+			for (int i = 1; i <= count; i++)
+            {
+                if (input[input.Length - i] != count)
+                {
+                    throw new InvalidCipherTextException("pad block corrupted");
+                }
+            }
+
+            return count;
+        }
+    }
+
+}