libjava/gnu/java/security/provider/DERReader.java

   1 /* DERReader.java
   2    Copyright (C) 1999 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package gnu.java.security.provider;
  40
  41 import java.math.BigInteger;
  42 import gnu.java.security.der.DEREncodingException;
  43
  44 public class DERReader
  45 {
  46   byte source[];
  47   int pos;
  48
  49   static final int UNIVERSAL = 1;
  50   static final int APPLICATION = 2;
  51   static final int CONTEXT_SPECIFIC = 3;
  52   static final int PRIVATE = 4;
  53
  54
  55   public DERReader()
  56   {
  57     source = null;
  58     pos = 0;
  59   }
  60
  61   public DERReader( byte source[] )
  62   {
  63     init( source );
  64   }
  65
  66   public void init( String source )
  67   {
  68     init( source.getBytes() );
  69   }
  70
  71   public void init( byte source[] )
  72   {
  73     this.source = source;
  74     pos = 0;
  75   }
  76
  77   public BigInteger getBigInteger() throws DEREncodingException
  78   {
  79     return new BigInteger( getPrimitive() );
  80   }
  81
  82   //Reads Primitive, definite-length method
  83   private byte[] getPrimitive() throws DEREncodingException
  84   {
  85     int tmp = pos;
  86
  87     //Read Identifier
  88     byte identifier = source[tmp++];
  89     if( (0x20 & identifier) != 0)
  90       throw new DEREncodingException();
  91     int type = translateLeadIdentifierByte(identifier);
  92     //System.out.println("Type: " + type);
  93
  94     //get tag
  95     int tag = (0x1f & identifier);
  96     //if( tag == 0x1f)
  97     //  tag = getIdentifier(tmp);
  98     //System.out.println("Tag: " + tag);
  99
 100     //get length
 101     byte len = source[tmp]; //may be length of length parameter
 102     long length =  0x7f & len;
 103     int i;
 104     if( (0x80 & len) != 0 ) {
 105       //System.out.println("Extra Long Length");
 106       len &= 0x7f;
 107       //System.out.println("Length of Length: " + len);
 108       //get length here
 109       length = 0;
 110       for( i = 0; i < len; i++ ) {
 111         tmp++;
 112         length <<= 8;
 113         length += (source[tmp] < 0 ) ?
 114           (256 + source[tmp]) :
 115           source[tmp];
 116         //System.out.println("Length of Length: " + length);
 117       }
 118       tmp++;
 119     } else
 120       tmp++;
 121
 122     /*System.out.println("Position: " + tmp);
 123       System.out.println("Length: " + length);
 124       for( i = 0; i < 10; i++)
 125       System.out.print(source[tmp + i] + " ");
 126       System.out.println();*/
 127
 128     byte tmpb[] = new byte[ (int)length ];
 129     System.arraycopy( source, tmp, tmpb, 0, (int)length);
 130     pos = (int)(tmp + length);
 131     return tmpb;
 132   }
 133
 134   private int translateLeadIdentifierByte(byte b)
 135   {
 136     if( (0x3f & b ) == b)
 137       return UNIVERSAL;
 138     else if( (0x7f & b ) == b)
 139       return APPLICATION;
 140     else if( (0xbf & b ) == b)
 141       return CONTEXT_SPECIFIC;
 142     else
 143       return PRIVATE;
 144   }
 145
 146   private int getIdentifier(int tpos)
 147   {
 148     while( (0x80 & source[tpos]) != 0)
 149       tpos++;
 150     return tpos;
 151   }
 152 }