1 files changed, 72 insertions, 3 deletions

diff --git a/lib/src/main/java/com/trilead/ssh2/crypto/SimpleDERReader.java b/lib/src/main/java/com/trilead/ssh2/crypto/SimpleDERReader.java
index 9f626ad..ff8112a 100644
--- a/lib/src/main/java/com/trilead/ssh2/crypto/SimpleDERReader.java
+++ b/lib/src/main/java/com/trilead/ssh2/crypto/SimpleDERReader.java
@@ -12,6 +12,8 @@ import java.math.BigInteger;
  */
 public class SimpleDERReader
 {
+	private static final int CONSTRUCTED = 0x20;
+
 	byte[] buffer;
 	int pos;
 	int count;
@@ -123,6 +125,30 @@ public class SimpleDERReader
 		return bi;
 	}
 
+	public int readConstructedType() throws IOException {
+		int type = readByte() & 0xff;
+
+		if ((type & CONSTRUCTED) != CONSTRUCTED)
+			throw new IOException("Expected constructed type, but was " + type);
+
+		return type & 0x1f;
+	}
+
+	public SimpleDERReader readConstructed() throws IOException
+	{
+		int len = readLength();
+
+		if ((len < 0) || len > available())
+			throw new IOException("Illegal len in DER object (" + len  + ")");
+
+		SimpleDERReader cr = new SimpleDERReader(buffer, pos, len);
+
+		pos += len;
+		count -= len;
+
+		return cr;
+	}
+
 	public byte[] readSequenceAsByteArray() throws IOException
 	{
 		int type = readByte() & 0xff;
@@ -139,12 +165,55 @@ public class SimpleDERReader
 
 		return b;
 	}
-	
+
+	public String readOid() throws IOException
+	{
+		int type = readByte() & 0xff;
+
+		if (type != 0x06)
+		   throw new IOException("Expected DER OID, but found type " + type);
+
+		int len = readLength();
+
+		if ((len < 1) || len > available())
+			throw new IOException("Illegal len in DER object (" + len  + ")");
+
+		byte[] b = readBytes(len);
+
+		long value = 0;
+
+		StringBuilder sb = new StringBuilder(64);
+		switch(b[0] / 40) {
+		case 0:
+			sb.append('0');
+			break;
+		case 1:
+			sb.append('1');
+			b[0] -= 40;
+			break;
+		default:
+			sb.append('2');
+			b[0] -= 80;
+			break;
+		}
+
+		for (int i = 0; i < len; i++) {
+			value = (value << 7) + (b[i] & 0x7F);
+			if ((b[i] & 0x80) == 0) {
+				sb.append('.');
+				sb.append(value);
+				value = 0;
+			}
+		}
+
+		return sb.toString();
+	}
+
 	public byte[] readOctetString() throws IOException
 	{
 		int type = readByte() & 0xff;
-		
-		if (type != 0x04)
+
+		if (type != 0x04 && type != 0x03)
 			throw new IOException("Expected DER Octetstring, but found type " + type);
 		
 		int len = readLength();