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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);
}
}
}
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