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DERBitString.javaAPI DocAndroid 1.5 API6751Wed May 06 22:41:06 BST 2009org.bouncycastle.asn1

DERBitString

public class DERBitString extends DERObject implements DERString

Fields Summary
private static final char[]
table
protected byte[]
data
protected int
padBits
Constructors Summary
protected DERBitString(byte data, int padBits)

        this.data = new byte[1];
        this.data[0] = data;
        this.padBits = padBits;
public DERBitString(byte[] data, int padBits)

param
data the octets making up the bit string.
param
padBits the number of extra bits at the end of the string.

        this.data = data;
        this.padBits = padBits;
public DERBitString(byte[] data)

        this(data, 0);
public DERBitString(DEREncodable obj)

        try
        {
            ByteArrayOutputStream   bOut = new ByteArrayOutputStream();
            DEROutputStream         dOut = new DEROutputStream(bOut);

            dOut.writeObject(obj);
            dOut.close();

            this.data = bOut.toByteArray();
            this.padBits = 0;
        }
        catch (IOException e)
        {
            throw new IllegalArgumentException("Error processing object : " + e.toString());
        }
Methods Summary
voidencode(DEROutputStream out)

        byte[]  bytes = new byte[getBytes().length + 1];

        bytes[0] = (byte)getPadBits();
        System.arraycopy(getBytes(), 0, bytes, 1, bytes.length - 1);

        out.writeEncoded(BIT_STRING, bytes);
public booleanequals(java.lang.Object o)

        if (!(o instanceof DERBitString))
        {
            return false;
        }

        DERBitString  other = (DERBitString)o;

        if (data.length != other.data.length)
        {
            return false;
        }

        for (int i = 0; i != data.length; i++)
        {
            if (data[i] != other.data[i])
            {
                return false;
            }
        }

        return (padBits == other.padBits);
protected static byte[]getBytes(int bitString)
return the correct number of bytes for a bit string defined in a 32 bit constant

        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;
public byte[]getBytes()

        return data;
public static org.bouncycastle.asn1.DERBitStringgetInstance(java.lang.Object obj)
return a Bit String from the passed in object

exception
IllegalArgumentException if the object cannot be converted.

        if (obj == null || obj instanceof DERBitString)
        {
            return (DERBitString)obj;
        }

        if (obj instanceof ASN1OctetString)
        {
            byte[]  bytes = ((ASN1OctetString)obj).getOctets();
            int     padBits = bytes[0];
            byte[]  data = new byte[bytes.length - 1];

            System.arraycopy(bytes, 1, data, 0, bytes.length - 1);

            return new DERBitString(data, padBits);
        }

        if (obj instanceof ASN1TaggedObject)
        {
            return getInstance(((ASN1TaggedObject)obj).getObject());
        }

        throw new IllegalArgumentException("illegal object in getInstance: " + obj.getClass().getName());
public static org.bouncycastle.asn1.DERBitStringgetInstance(ASN1TaggedObject obj, boolean explicit)
return a Bit String from a tagged object.

param
obj the tagged object holding the object we want
param
explicit true if the object is meant to be explicitly tagged false otherwise.
exception
IllegalArgumentException if the tagged object cannot be converted.

        return getInstance(obj.getObject());
protected static intgetPadBits(int bitString)
return the correct number of pad bits for a bit string defined in a 32 bit constant


                          
       
         
    
        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;
public intgetPadBits()

        return padBits;
public java.lang.StringgetString()

        StringBuffer          buf = new StringBuffer("#");
        ByteArrayOutputStream bOut = new ByteArrayOutputStream();
        ASN1OutputStream      aOut = new ASN1OutputStream(bOut);
        
        try
        {
            aOut.writeObject(this);
        }
        catch (IOException e)
        {
           throw new RuntimeException("internal error encoding BitString");
        }
        
        byte[]    string = bOut.toByteArray();
        
        for (int i = 0; i != string.length; i++)
        {
            buf.append(table[(string[i] >>> 4) % 0xf]);
            buf.append(table[string[i] & 0xf]);
        }
        
        return buf.toString();
public inthashCode()

        int     value = 0;

        for (int i = 0; i != data.length; i++)
        {
            value ^= (data[i] & 0xff) << (i % 4);
        }

        return value;
public intintValue()

return
the value of the bit string as an int (truncating if necessary)

        int value = 0;
        
        for (int i = 0; i != data.length && i != 4; i++)
        {
            value |= (data[i] & 0xff) << (8 * i);
        }
        
        return value;
public java.lang.StringtoString()

        return getString();