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      1 package org.bouncycastle.asn1.x509;
      2 
      3 import org.bouncycastle.asn1.ASN1Encodable;
      4 import org.bouncycastle.asn1.ASN1EncodableVector;
      5 import org.bouncycastle.asn1.ASN1Object;
      6 import org.bouncycastle.asn1.ASN1ObjectIdentifier;
      7 import org.bouncycastle.asn1.ASN1Primitive;
      8 import org.bouncycastle.asn1.ASN1Sequence;
      9 import org.bouncycastle.asn1.ASN1TaggedObject;
     10 import org.bouncycastle.asn1.DERSequence;
     11 
     12 public class AlgorithmIdentifier
     13     extends ASN1Object
     14 {
     15     private ASN1ObjectIdentifier algorithm;
     16     private ASN1Encodable       parameters;
     17 
     18     public static AlgorithmIdentifier getInstance(
     19         ASN1TaggedObject obj,
     20         boolean          explicit)
     21     {
     22         return getInstance(ASN1Sequence.getInstance(obj, explicit));
     23     }
     24 
     25     public static AlgorithmIdentifier getInstance(
     26         Object  obj)
     27     {
     28         if (obj instanceof AlgorithmIdentifier)
     29         {
     30             return (AlgorithmIdentifier)obj;
     31         }
     32         else if (obj != null)
     33         {
     34             return new AlgorithmIdentifier(ASN1Sequence.getInstance(obj));
     35         }
     36 
     37         return null;
     38     }
     39 
     40     public AlgorithmIdentifier(
     41         ASN1ObjectIdentifier algorithm)
     42     {
     43         this.algorithm = algorithm;
     44     }
     45 
     46     public AlgorithmIdentifier(
     47         ASN1ObjectIdentifier algorithm,
     48         ASN1Encodable           parameters)
     49     {
     50         this.algorithm = algorithm;
     51         this.parameters = parameters;
     52     }
     53 
     54     private AlgorithmIdentifier(
     55         ASN1Sequence   seq)
     56     {
     57         if (seq.size() < 1 || seq.size() > 2)
     58         {
     59             throw new IllegalArgumentException("Bad sequence size: "
     60                     + seq.size());
     61         }
     62 
     63         algorithm = ASN1ObjectIdentifier.getInstance(seq.getObjectAt(0));
     64 
     65         if (seq.size() == 2)
     66         {
     67             parameters = seq.getObjectAt(1);
     68         }
     69         else
     70         {
     71             parameters = null;
     72         }
     73     }
     74 
     75     public ASN1ObjectIdentifier getAlgorithm()
     76     {
     77         return algorithm;
     78     }
     79 
     80     public ASN1Encodable getParameters()
     81     {
     82         return parameters;
     83     }
     84 
     85     /**
     86      * Produce an object suitable for an ASN1OutputStream.
     87      * <pre>
     88      *      AlgorithmIdentifier ::= SEQUENCE {
     89      *                            algorithm OBJECT IDENTIFIER,
     90      *                            parameters ANY DEFINED BY algorithm OPTIONAL }
     91      * </pre>
     92      */
     93     public ASN1Primitive toASN1Primitive()
     94     {
     95         ASN1EncodableVector  v = new ASN1EncodableVector();
     96 
     97         v.add(algorithm);
     98 
     99         if (parameters != null)
    100         {
    101             v.add(parameters);
    102         }
    103 
    104         return new DERSequence(v);
    105     }
    106 }
    107