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      1 package org.bouncycastle.asn1;
      2 
      3 import java.io.IOException;
      4 import java.math.BigInteger;
      5 
      6 import org.bouncycastle.util.Arrays;
      7 
      8 public class DERInteger
      9     extends ASN1Object
     10 {
     11     byte[]      bytes;
     12 
     13     /**
     14      * return an integer from the passed in object
     15      *
     16      * @exception IllegalArgumentException if the object cannot be converted.
     17      */
     18     public static DERInteger getInstance(
     19         Object  obj)
     20     {
     21         if (obj == null || obj instanceof DERInteger)
     22         {
     23             return (DERInteger)obj;
     24         }
     25 
     26         if (obj instanceof ASN1OctetString)
     27         {
     28             return new DERInteger(((ASN1OctetString)obj).getOctets());
     29         }
     30 
     31         if (obj instanceof ASN1TaggedObject)
     32         {
     33             return getInstance(((ASN1TaggedObject)obj).getObject());
     34         }
     35 
     36         throw new IllegalArgumentException("illegal object in getInstance: " + obj.getClass().getName());
     37     }
     38 
     39     /**
     40      * return an Integer from a tagged object.
     41      *
     42      * @param obj the tagged object holding the object we want
     43      * @param explicit true if the object is meant to be explicitly
     44      *              tagged false otherwise.
     45      * @exception IllegalArgumentException if the tagged object cannot
     46      *               be converted.
     47      */
     48     public static DERInteger getInstance(
     49         ASN1TaggedObject obj,
     50         boolean          explicit)
     51     {
     52         return getInstance(obj.getObject());
     53     }
     54 
     55     public DERInteger(
     56         int         value)
     57     {
     58         bytes = BigInteger.valueOf(value).toByteArray();
     59     }
     60 
     61     public DERInteger(
     62         BigInteger   value)
     63     {
     64         bytes = value.toByteArray();
     65     }
     66 
     67     public DERInteger(
     68         byte[]   bytes)
     69     {
     70         this.bytes = bytes;
     71     }
     72 
     73     public BigInteger getValue()
     74     {
     75         return new BigInteger(bytes);
     76     }
     77 
     78     /**
     79      * in some cases positive values get crammed into a space,
     80      * that's not quite big enough...
     81      */
     82     public BigInteger getPositiveValue()
     83     {
     84         return new BigInteger(1, bytes);
     85     }
     86 
     87     void encode(
     88         DEROutputStream out)
     89         throws IOException
     90     {
     91         out.writeEncoded(INTEGER, bytes);
     92     }
     93 
     94     public int hashCode()
     95     {
     96          int     value = 0;
     97 
     98          for (int i = 0; i != bytes.length; i++)
     99          {
    100              value ^= (bytes[i] & 0xff) << (i % 4);
    101          }
    102 
    103          return value;
    104     }
    105 
    106     boolean asn1Equals(
    107         DERObject  o)
    108     {
    109         if (!(o instanceof DERInteger))
    110         {
    111             return false;
    112         }
    113 
    114         DERInteger other = (DERInteger)o;
    115 
    116         return Arrays.areEqual(bytes, other.bytes);
    117     }
    118 
    119     public String toString()
    120     {
    121       return getValue().toString();
    122     }
    123 }
    124