1 files changed, 248 insertions, 0 deletions
diff --git a/crypto/src/asn1/DerBitString.cs b/crypto/src/asn1/DerBitString.cs
new file mode 100644
index 000000000..d5cb872bc
--- /dev/null
+++ b/crypto/src/asn1/DerBitString.cs
@@ -0,0 +1,248 @@
+using System;
+using System.Text;
+
+using Org.BouncyCastle.Utilities;
+
+namespace Org.BouncyCastle.Asn1
+{
+	public class DerBitString
+		: DerStringBase
+	{
+		private static readonly char[] table
+			= { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
+
+		private readonly byte[]	data;
+		private readonly int	padBits;
+
+		/**
+		 * return the correct number of pad bits for a bit string defined in
+		 * a 32 bit constant
+		 */
+		static internal int GetPadBits(
+			int bitString)
+		{
+			int val = 0;
+			for (int i = 3; i >= 0; i--)
+			{
+				//
+				// this may look a little odd, but if it isn't done like this pre jdk1.2
+				// JVM's break!
+				//
+				if (i != 0)
+				{
+					if ((bitString >> (i * 8)) != 0)
+					{
+						val = (bitString >> (i * 8)) & 0xFF;
+						break;
+					}
+				}
+				else
+				{
+					if (bitString != 0)
+					{
+						val = bitString & 0xFF;
+						break;
+					}
+				}
+			}
+
+			if (val == 0)
+			{
+				return 7;
+			}
+
+			int bits = 1;
+
+			while (((val <<= 1) & 0xFF) != 0)
+			{
+				bits++;
+			}
+
+			return 8 - bits;
+		}
+
+		/**
+		 * return the correct number of bytes for a bit string defined in
+		 * a 32 bit constant
+		 */
+		static internal byte[] GetBytes(
+			int bitString)
+		{
+			int bytes = 4;
+			for (int i = 3; i >= 1; i--)
+			{
+				if ((bitString & (0xFF << (i * 8))) != 0)
+				{
+					break;
+				}
+				bytes--;
+			}
+
+			byte[] result = new byte[bytes];
+			for (int i = 0; i < bytes; i++)
+			{
+				result[i] = (byte) ((bitString >> (i * 8)) & 0xFF);
+			}
+
+			return result;
+		}
+
+		/**
+		 * return a Bit string from the passed in object
+		 *
+		 * @exception ArgumentException if the object cannot be converted.
+		 */
+		public static DerBitString GetInstance(
+			object obj)
+		{
+			if (obj == null || obj is DerBitString)
+			{
+				return (DerBitString) obj;
+			}
+
+			throw new ArgumentException("illegal object in GetInstance: " + obj.GetType().Name);
+		}
+
+		/**
+		 * return a Bit string from a tagged object.
+		 *
+		 * @param obj the tagged object holding the object we want
+		 * @param explicitly true if the object is meant to be explicitly
+		 *              tagged false otherwise.
+		 * @exception ArgumentException if the tagged object cannot
+		 *               be converted.
+		 */
+		public static DerBitString GetInstance(
+			Asn1TaggedObject	obj,
+			bool				isExplicit)
+		{
+			Asn1Object o = obj.GetObject();
+
+			if (isExplicit || o is DerBitString)
+			{
+				return GetInstance(o);
+			}
+
+			return FromAsn1Octets(((Asn1OctetString)o).GetOctets());
+		}
+
+		internal DerBitString(
+			byte	data,
+			int		padBits)
+		{
+			this.data = new byte[]{ data };
+			this.padBits = padBits;
+		}
+
+		/**
+		 * @param data the octets making up the bit string.
+		 * @param padBits the number of extra bits at the end of the string.
+		 */
+		public DerBitString(
+			byte[]	data,
+			int		padBits)
+		{
+			// TODO Deep copy?
+			this.data = data;
+			this.padBits = padBits;
+		}
+
+		public DerBitString(
+			byte[] data)
+		{
+			// TODO Deep copy?
+			this.data = data;
+		}
+
+		public DerBitString(
+			Asn1Encodable obj)
+		{
+			this.data = obj.GetDerEncoded();
+			//this.padBits = 0;
+		}
+
+		public byte[] GetBytes()
+		{
+			return data;
+		}
+
+		public int PadBits
+		{
+			get { return padBits; }
+		}
+
+		/**
+		 * @return the value of the bit string as an int (truncating if necessary)
+		 */
+		public int IntValue
+		{
+			get
+			{
+				int value = 0;
+
+				for (int i = 0; i != data.Length && i != 4; i++)
+				{
+					value |= (data[i] & 0xff) << (8 * i);
+				}
+
+				return value;
+			}
+		}
+
+		internal override void Encode(
+			DerOutputStream derOut)
+		{
+			byte[] bytes = new byte[GetBytes().Length + 1];
+
+			bytes[0] = (byte) PadBits;
+			Array.Copy(GetBytes(), 0, bytes, 1, bytes.Length - 1);
+
+			derOut.WriteEncoded(Asn1Tags.BitString, bytes);
+		}
+
+		protected override int Asn1GetHashCode()
+		{
+			return padBits.GetHashCode() ^ Arrays.GetHashCode(data);
+		}
+
+		protected override bool Asn1Equals(
+			Asn1Object asn1Object)
+		{
+			DerBitString other = asn1Object as DerBitString;
+
+			if (other == null)
+				return false;
+
+			return this.padBits == other.padBits
+				&& Arrays.AreEqual(this.data, other.data);
+		}
+
+		public override string GetString()
+		{
+			StringBuilder buffer = new StringBuilder("#");
+
+			byte[] str = GetDerEncoded();
+
+			for (int i = 0; i != str.Length; i++)
+			{
+				uint ubyte = str[i];
+				buffer.Append(table[(ubyte >> 4) & 0xf]);
+				buffer.Append(table[str[i] & 0xf]);
+			}
+
+			return buffer.ToString();
+		}
+
+		internal static DerBitString FromAsn1Octets(byte[] octets)
+		{
+	        if (octets.Length < 1)
+	            throw new ArgumentException("truncated BIT STRING detected");
+
+			int padBits = octets[0];
+			byte[] data = new byte[octets.Length - 1];
+			Array.Copy(octets, 1, data, 0, data.Length);
+			return new DerBitString(data, padBits);
+		}
+	}
+}
+