1 files changed, 85 insertions, 0 deletions
diff --git a/crypto/src/asn1/DerSequence.cs b/crypto/src/asn1/DerSequence.cs
new file mode 100644
index 000000000..b50a77962
--- /dev/null
+++ b/crypto/src/asn1/DerSequence.cs
@@ -0,0 +1,85 @@
+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);
+		}
+	}
+}