Initial Commit

iTechSharp/srcbc/crypto/paddings/ISO7816d4Padding.cs

@@ -0,0 +1,79 @@
+using System;
+
+using Org.BouncyCastle.Crypto;
+using Org.BouncyCastle.Security;
+
+namespace Org.BouncyCastle.Crypto.Paddings
+{
+	/**
+	 * A padder that adds the padding according to the scheme referenced in
+	 * ISO 7814-4 - scheme 2 from ISO 9797-1. The first byte is 0x80, rest is 0x00
+	 */
+	public class ISO7816d4Padding
+		: 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 padder implements.
+		 *
+		 * @return the name of the algorithm the padder implements.
+		 */
+		public string PaddingName
+		{
+			get { return "ISO7816-4"; }
+		}
+
+		/**
+		 * add the pad bytes to the passed in block, returning the
+		 * number of bytes added.
+		 */
+		public int AddPadding(
+			byte[]	input,
+			int		inOff)
+		{
+			int added = (input.Length - inOff);
+
+			input[inOff]= (byte) 0x80;
+			inOff ++;
+
+			while (inOff < input.Length)
+			{
+				input[inOff] = (byte) 0;
+				inOff++;
+			}
+
+			return added;
+		}
+
+		/**
+		 * return the number of pad bytes present in the block.
+		 */
+		public int PadCount(
+			byte[] input)
+		{
+			int count = input.Length - 1;
+
+			while (count > 0 && input[count] == 0)
+			{
+				count--;
+			}
+
+			if (input[count] != (byte)0x80)
+			{
+				throw new InvalidCipherTextException("pad block corrupted");
+			}
+
+			return input.Length - count;
+		}
+	}
+}