DerSequence.cs :  » PDF » iTextSharp » Org » BouncyCastle » Asn1 » C# / CSharp Open Source

using System.Collections;
using System.IO;

namespace Org.BouncyCastle.Asn1{
  public class DerSequence
    : Asn1Sequence
  {
    public static readonly DerSequence Empty = new DerSequence();

    public static DerSequence FromVector(
      Asn1EncodableVector v)
    {
      return v.Count < 1 ? Empty : new DerSequence(v);
    }

    /**
     * create an empty sequence
     */
    public DerSequence()
      : base(0)
    {
    }

    /**
     * create a sequence containing one object
     */
    public DerSequence(
      Asn1Encodable obj)
      : base(1)
    {
      AddObject(obj);
    }

    public DerSequence(
      params Asn1Encodable[] v)
      : base(v.Length)
    {
      foreach (Asn1Encodable ae in v)
      {
        AddObject(ae);
      }
    }

    /**
     * create a sequence containing a vector of objects.
     */
    public DerSequence(
      Asn1EncodableVector v)
      : base(v.Count)
    {
      foreach (Asn1Encodable ae in v)
      {
        AddObject(ae);
      }
    }

    /*
     * A note on the implementation:
     * <p>
     * As Der requires the constructed, definite-length model to
     * be used for structured types, this varies slightly from the
     * ASN.1 descriptions given. Rather than just outputing Sequence,
     * we also have to specify Constructed, and the objects length.
     */
    internal override void Encode(
      DerOutputStream derOut)
    {
      // TODO Intermediate buffer could be avoided if we could calculate expected length
      MemoryStream bOut = new MemoryStream();
      DerOutputStream dOut = new DerOutputStream(bOut);

      foreach (Asn1Encodable obj in this)
      {
        dOut.WriteObject(obj);
      }

      dOut.Close();

      byte[] bytes = bOut.ToArray();

      derOut.WriteEncoded(Asn1Tags.Sequence | Asn1Tags.Constructed, bytes);
    }
  }
}