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

using System;

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Utilities;

namespace Org.BouncyCastle.Asn1.Sec{
  /**
   * the elliptic curve private key object from SEC 1
   */
  public class ECPrivateKeyStructure
    : Asn1Encodable
  {
    private readonly Asn1Sequence seq;

    public ECPrivateKeyStructure(
      Asn1Sequence seq)
    {
      if (seq == null)
        throw new ArgumentNullException("seq");

      this.seq = seq;
    }

    public ECPrivateKeyStructure(
      BigInteger key)
    {
      if (key == null)
        throw new ArgumentNullException("key");

      this.seq = new DerSequence(
        new DerInteger(1),
        new DerOctetString(key.ToByteArrayUnsigned()));
    }

    public ECPrivateKeyStructure(
      BigInteger    key,
      Asn1Encodable  parameters)
      : this(key, null, parameters)
    {
    }

    public ECPrivateKeyStructure(
      BigInteger    key,
      DerBitString  publicKey,
      Asn1Encodable  parameters)
    {
      if (key == null)
        throw new ArgumentNullException("key");

      Asn1EncodableVector v = new Asn1EncodableVector(
        new DerInteger(1),
        new DerOctetString(key.ToByteArrayUnsigned()));

      if (parameters != null)
      {
        v.Add(new DerTaggedObject(true, 0, parameters));
      }

      if (publicKey != null)
      {
        v.Add(new DerTaggedObject(true, 1, publicKey));
      }

      this.seq = new DerSequence(v);
    }

    public BigInteger GetKey()
    {
      Asn1OctetString octs = (Asn1OctetString) seq[1];

      return new BigInteger(1, octs.GetOctets());
    }

    public DerBitString GetPublicKey()
    {
      return (DerBitString) GetObjectInTag(1);
    }

    public Asn1Object GetParameters()
    {
      return GetObjectInTag(0);
    }

    private Asn1Object GetObjectInTag(
      int tagNo)
    {
      foreach (Asn1Encodable ae in seq)
      {
        Asn1Object obj = ae.ToAsn1Object();

        if (obj is Asn1TaggedObject)
        {
          Asn1TaggedObject tag = (Asn1TaggedObject) obj;
          if (tag.TagNo == tagNo)
          {
            return tag.GetObject();
          }
        }
      }

      return null;
    }

    /**
     * ECPrivateKey ::= SEQUENCE {
     *     version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1),
     *     privateKey OCTET STRING,
     *     parameters [0] Parameters OPTIONAL,
     *     publicKey [1] BIT STRING OPTIONAL }
     */
    public override Asn1Object ToAsn1Object()
    {
      return seq;
    }
  }
}