diff --git a/Crypto/src/asn1/DERGenerator.cs b/Crypto/src/asn1/DERGenerator.cs
new file mode 100644
index 000000000..aab40fefa
--- /dev/null
+++ b/Crypto/src/asn1/DERGenerator.cs
@@ -0,0 +1,107 @@
+using System.IO;
+
+using Org.BouncyCastle.Utilities.IO;
+
+namespace Org.BouncyCastle.Asn1
+{
+ public abstract class DerGenerator
+ : Asn1Generator
+ {
+ private bool _tagged = false;
+ private bool _isExplicit;
+ private int _tagNo;
+
+ protected DerGenerator(
+ Stream outStream)
+ : base(outStream)
+ {
+ }
+
+ protected DerGenerator(
+ Stream outStream,
+ int tagNo,
+ bool isExplicit)
+ : base(outStream)
+ {
+ _tagged = true;
+ _isExplicit = isExplicit;
+ _tagNo = tagNo;
+ }
+
+ private static void WriteLength(
+ Stream outStr,
+ int length)
+ {
+ if (length > 127)
+ {
+ int size = 1;
+ int val = length;
+
+ while ((val >>= 8) != 0)
+ {
+ size++;
+ }
+
+ outStr.WriteByte((byte)(size | 0x80));
+
+ for (int i = (size - 1) * 8; i >= 0; i -= 8)
+ {
+ outStr.WriteByte((byte)(length >> i));
+ }
+ }
+ else
+ {
+ outStr.WriteByte((byte)length);
+ }
+ }
+
+ internal static void WriteDerEncoded(
+ Stream outStream,
+ int tag,
+ byte[] bytes)
+ {
+ outStream.WriteByte((byte) tag);
+ WriteLength(outStream, bytes.Length);
+ outStream.Write(bytes, 0, bytes.Length);
+ }
+
+ internal void WriteDerEncoded(
+ int tag,
+ byte[] bytes)
+ {
+ if (_tagged)
+ {
+ int tagNum = _tagNo | Asn1Tags.Tagged;
+
+ if (_isExplicit)
+ {
+ int newTag = _tagNo | Asn1Tags.Constructed | Asn1Tags.Tagged;
+ MemoryStream bOut = new MemoryStream();
+ WriteDerEncoded(bOut, tag, bytes);
+ WriteDerEncoded(Out, newTag, bOut.ToArray());
+ }
+ else
+ {
+ if ((tag & Asn1Tags.Constructed) != 0)
+ {
+ tagNum |= Asn1Tags.Constructed;
+ }
+
+ WriteDerEncoded(Out, tagNum, bytes);
+ }
+ }
+ else
+ {
+ WriteDerEncoded(Out, tag, bytes);
+ }
+ }
+
+ internal static void WriteDerEncoded(
+ Stream outStr,
+ int tag,
+ Stream inStr)
+ {
+ WriteDerEncoded(outStr, tag, Streams.ReadAll(inStr));
+ }
+ }
+}
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