1 files changed, 119 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/asn1/DERGenerator.java b/core/src/main/java/org/spongycastle/asn1/DERGenerator.java
new file mode 100644
index 00000000..da6d6545
--- /dev/null
+++ b/core/src/main/java/org/spongycastle/asn1/DERGenerator.java
@@ -0,0 +1,119 @@
+package org.spongycastle.asn1;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+import org.spongycastle.util.io.Streams;
+
+public abstract class DERGenerator
+    extends ASN1Generator
+{       
+    private boolean      _tagged = false;
+    private boolean      _isExplicit;
+    private int          _tagNo;
+    
+    protected DERGenerator(
+        OutputStream out)
+    {
+        super(out);
+    }
+
+    public DERGenerator(
+        OutputStream out,
+        int          tagNo,
+        boolean      isExplicit)
+    { 
+        super(out);
+        
+        _tagged = true;
+        _isExplicit = isExplicit;
+        _tagNo = tagNo;
+    }
+
+    private void writeLength(
+        OutputStream out,
+        int          length)
+        throws IOException
+    {
+        if (length > 127)
+        {
+            int size = 1;
+            int val = length;
+
+            while ((val >>>= 8) != 0)
+            {
+                size++;
+            }
+
+            out.write((byte)(size | 0x80));
+
+            for (int i = (size - 1) * 8; i >= 0; i -= 8)
+            {
+                out.write((byte)(length >> i));
+            }
+        }
+        else
+        {
+            out.write((byte)length);
+        }
+    }
+
+    void writeDEREncoded(
+        OutputStream out,
+        int          tag,
+        byte[]       bytes)
+        throws IOException
+    {
+        out.write(tag);
+        writeLength(out, bytes.length);
+        out.write(bytes);
+    }
+
+    void writeDEREncoded(
+        int       tag,
+        byte[]    bytes)
+        throws IOException
+    {
+        if (_tagged)
+        {
+            int tagNum = _tagNo | BERTags.TAGGED;
+            
+            if (_isExplicit)
+            {
+                int newTag = _tagNo | BERTags.CONSTRUCTED | BERTags.TAGGED;
+
+                ByteArrayOutputStream bOut = new ByteArrayOutputStream();
+                
+                writeDEREncoded(bOut, tag, bytes);
+                
+                writeDEREncoded(_out, newTag, bOut.toByteArray());
+            }
+            else
+            {   
+                if ((tag & BERTags.CONSTRUCTED) != 0)
+                {
+                    writeDEREncoded(_out, tagNum | BERTags.CONSTRUCTED, bytes);
+                }
+                else
+                {
+                    writeDEREncoded(_out, tagNum, bytes);
+                }
+            }
+        }
+        else
+        {
+            writeDEREncoded(_out, tag, bytes);
+        }
+    }
+    
+    void writeDEREncoded(
+        OutputStream out,
+        int          tag,
+        InputStream  in)
+        throws IOException
+    {
+        writeDEREncoded(out, tag, Streams.readAll(in));
+    }
+}