SignatureSubpacketsReader.cs :  » PDF » iTextSharp » Org » BouncyCastle » Bcpg » C# / CSharp Open Source

using System;
using System.IO;
using Org.BouncyCastle.Bcpg.Sig;
using Org.BouncyCastle.Utilities.IO;

namespace Org.BouncyCastle.Bcpg{
  /**
  * reader for signature sub-packets
  */
  public class SignatureSubpacketsParser
  {
    private readonly Stream input;

    public SignatureSubpacketsParser(
      Stream input)
    {
      this.input = input;
    }

    public SignatureSubpacket ReadPacket()
    {
      int l = input.ReadByte();
      if (l < 0)
        return null;

      int bodyLen = 0;
      if (l < 192)
      {
        bodyLen = l;
      }
      else if (l <= 223)
      {
        bodyLen = ((l - 192) << 8) + (input.ReadByte()) + 192;
      }
      else if (l == 255)
      {
        bodyLen = (input.ReadByte() << 24) | (input.ReadByte() << 16)
          |  (input.ReadByte() << 8)  | input.ReadByte();
      }
      else
      {
        // TODO Error?
      }

      int tag = input.ReadByte();
      if (tag < 0)
        throw new EndOfStreamException("unexpected EOF reading signature sub packet");

      byte[] data = new byte[bodyLen - 1];
      if (Streams.ReadFully(input, data) < data.Length)
        throw new EndOfStreamException();

      bool isCritical = ((tag & 0x80) != 0);
      SignatureSubpacketTag type = (SignatureSubpacketTag)(tag & 0x7f);
      switch (type)
      {
        case SignatureSubpacketTag.CreationTime:
          return new SignatureCreationTime(isCritical, data);
        case SignatureSubpacketTag.KeyExpireTime:
          return new KeyExpirationTime(isCritical, data);
        case SignatureSubpacketTag.ExpireTime:
          return new SignatureExpirationTime(isCritical, data);
        case SignatureSubpacketTag.Revocable:
          return new Revocable(isCritical, data);
        case SignatureSubpacketTag.Exportable:
          return new Exportable(isCritical, data);
        case SignatureSubpacketTag.IssuerKeyId:
          return new IssuerKeyId(isCritical, data);
        case SignatureSubpacketTag.TrustSig:
          return new TrustSignature(isCritical, data);
        case SignatureSubpacketTag.PreferredCompressionAlgorithms:
        case SignatureSubpacketTag.PreferredHashAlgorithms:
        case SignatureSubpacketTag.PreferredSymmetricAlgorithms:
          return new PreferredAlgorithms(type, isCritical, data);
        case SignatureSubpacketTag.KeyFlags:
          return new KeyFlags(isCritical, data);
        case SignatureSubpacketTag.PrimaryUserId:
          return new PrimaryUserId(isCritical, data);
        case SignatureSubpacketTag.SignerUserId:
          return new SignerUserId(isCritical, data);
        case SignatureSubpacketTag.NotationData:
          return new NotationData(isCritical, data);
      }
      return new SignatureSubpacket(type, isCritical, data);
    }
  }
}