package com.lowagie.bc.asn1; import java.io.ByteArrayOutputStream; import java.io.IOException; public class DERBitString extends DERObject implements DERString { private static final char[] table = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' }; protected byte[] data; protected int padBits; /** * return the correct number of pad bits for a bit string defined in * a 32 bit constant */ static protected 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 protected 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 IllegalArgumentException if the object cannot be converted. */ public static DERBitString getInstance( Object obj) { 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()); } /** * 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. */ public static DERBitString getInstance( ASN1TaggedObject obj, boolean explicit) { return getInstance(obj.getObject()); } protected DERBitString( byte data, int padBits) { this.data = new byte[1]; this.data[0] = 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) { 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()); } } public byte[] getBytes() { return data; } public int getPadBits() { return padBits; } void encode( DEROutputStream out) throws IOException { 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 int hashCode() { int value = 0; for (int i = 0; i != data.length; i++) { value ^= (data[i] & 0xff) << (i % 4); } return value; } public boolean equals( Object o) { if (o == null || !(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); } public String getString() { 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(); } }