public SemanticsInformation(
			Asn1Sequence seq)
        {
            if (seq.Count < 1)
            {
                throw new ArgumentException("no objects in SemanticsInformation");
            }

			IEnumerator e = seq.GetEnumerator();
			e.MoveNext();
            object obj = e.Current;
            if (obj is DerObjectIdentifier)
            {
                semanticsIdentifier = DerObjectIdentifier.GetInstance(obj);
                if (e.MoveNext())
                {
                    obj  = e.Current;
                }
                else
                {
                    obj  = null;
                }
            }

			if (obj  != null)
            {
                Asn1Sequence generalNameSeq = Asn1Sequence.GetInstance(obj );
                nameRegistrationAuthorities = new GeneralName[generalNameSeq.Count];
                for (int i= 0; i < generalNameSeq.Count; i++)
                {
                    nameRegistrationAuthorities[i] = GeneralName.GetInstance(generalNameSeq[i]);
                }
            }
        }
		private LdsSecurityObject(
			Asn1Sequence seq)
		{
			if (seq == null || seq.Count == 0)
				throw new ArgumentException("null or empty sequence passed.");

			IEnumerator e = seq.GetEnumerator();

			// version
			e.MoveNext();
			version = DerInteger.GetInstance(e.Current);
			// digestAlgorithmIdentifier
			e.MoveNext();
			digestAlgorithmIdentifier = AlgorithmIdentifier.GetInstance(e.Current);

			e.MoveNext();
			Asn1Sequence datagroupHashSeq = Asn1Sequence.GetInstance(e.Current);

			if (version.Value.Equals(BigInteger.One))
			{
				e.MoveNext();
				versionInfo = LdsVersionInfo.GetInstance(e.Current);
			}

			CheckDatagroupHashSeqSize(datagroupHashSeq.Count);

			datagroupHash = new DataGroupHash[datagroupHashSeq.Count];
			for (int i= 0; i< datagroupHashSeq.Count; i++)
			{
				datagroupHash[i] = DataGroupHash.GetInstance(datagroupHashSeq[i]);
			}
		}
		public DHParameter(
            Asn1Sequence seq)
        {
            IEnumerator e = seq.GetEnumerator();

			e.MoveNext();
            p = (DerInteger)e.Current;

			e.MoveNext();
            g = (DerInteger)e.Current;

			if (e.MoveNext())
            {
                l = (DerInteger) e.Current;
            }
        }
		private SignedData(
            Asn1Sequence seq)
        {
            IEnumerator e = seq.GetEnumerator();

			e.MoveNext();
            version = (DerInteger) e.Current;

			e.MoveNext();
            digestAlgorithms = (Asn1Set) e.Current;

			e.MoveNext();
            contentInfo = ContentInfo.GetInstance(e.Current);

			while (e.MoveNext())
            {
                Asn1Object o = (Asn1Object) e.Current;

				//
                // an interesting feature of SignedData is that there appear to be varying implementations...
                // for the moment we ignore anything which doesn't fit.
                //
                if (o is DerTaggedObject)
                {
                    DerTaggedObject tagged = (DerTaggedObject) o;

					switch (tagged.TagNo)
                    {
						case 0:
							certificates = Asn1Set.GetInstance(tagged, false);
							break;
						case 1:
							crls = Asn1Set.GetInstance(tagged, false);
							break;
						default:
							throw new ArgumentException("unknown tag value " + tagged.TagNo);
                    }
                }
                else
                {
                    signerInfos = (Asn1Set) o;
                }
            }
        }
		public SignerInfo(
            Asn1Sequence seq)
        {
            IEnumerator e = seq.GetEnumerator();

            e.MoveNext();
            version = (DerInteger) e.Current;

			e.MoveNext();
            sid = SignerIdentifier.GetInstance(e.Current);

			e.MoveNext();
            digAlgorithm = AlgorithmIdentifier.GetInstance(e.Current);

			e.MoveNext();
            object obj = e.Current;

			if (obj is Asn1TaggedObject)
            {
                authenticatedAttributes = Asn1Set.GetInstance((Asn1TaggedObject) obj, false);

				e.MoveNext();
                digEncryptionAlgorithm = AlgorithmIdentifier.GetInstance(e.Current);
            }
            else
            {
                authenticatedAttributes = null;
                digEncryptionAlgorithm = AlgorithmIdentifier.GetInstance(obj);
            }

			e.MoveNext();
            encryptedDigest = DerOctetString.GetInstance(e.Current);

			if (e.MoveNext())
            {
                unauthenticatedAttributes = Asn1Set.GetInstance((Asn1TaggedObject) e.Current, false);
            }
            else
            {
                unauthenticatedAttributes = null;
            }
        }
        /**
         * Updates the permitted ISet of these name constraints with the intersection
         * with the given subtree.
         *
         * @param permitted The permitted subtrees
         */

        public void IntersectPermittedSubtree(Asn1Sequence permitted)
        {
            IDictionary subtreesMap = Platform.CreateHashtable();

            // group in ISets in a map ordered by tag no.
            for (IEnumerator e = permitted.GetEnumerator(); e.MoveNext(); )
            {
                GeneralSubtree subtree = GeneralSubtree.GetInstance(e.Current);

                int tagNo = subtree.Base.TagNo;
                if (subtreesMap[tagNo] == null)
                {
                    subtreesMap[tagNo] = new HashSet();
                }

                ((ISet)subtreesMap[tagNo]).Add(subtree);
            }

            for (IEnumerator it = subtreesMap.GetEnumerator(); it.MoveNext(); )
            {
                DictionaryEntry entry = (DictionaryEntry)it.Current;

                // go through all subtree groups
                switch ((int)entry.Key )
                {
                    case 1:
                        permittedSubtreesEmail = IntersectEmail(permittedSubtreesEmail,
                            (ISet)entry.Value);
                        break;
                    case 2:
                        permittedSubtreesDNS = intersectDNS(permittedSubtreesDNS,
                            (ISet)entry.Value);
                        break;
                    case 4:
                        permittedSubtreesDN = IntersectDN(permittedSubtreesDN,
                            (ISet)entry.Value);
                        break;
                    case 6:
                        permittedSubtreesURI = intersectURI(permittedSubtreesURI,
                            (ISet)entry.Value);
                        break;
                    case 7:
                        permittedSubtreesIP = IntersectIP(permittedSubtreesIP,
                            (ISet)entry.Value);
                        break;
                }
            }
        }