1 files changed, 229 insertions, 0 deletions
diff --git a/app/src/main/java/com/trilead/ssh2/crypto/SimpleDERReader.java b/app/src/main/java/com/trilead/ssh2/crypto/SimpleDERReader.java
new file mode 100644
index 0000000..ff8112a
--- /dev/null
+++ b/app/src/main/java/com/trilead/ssh2/crypto/SimpleDERReader.java
@@ -0,0 +1,229 @@
+package com.trilead.ssh2.crypto;
+
+import java.io.IOException;
+
+import java.math.BigInteger;
+
+/**
+ * SimpleDERReader.
+ * 
+ * @author Christian Plattner, plattner@trilead.com
+ * @version $Id: SimpleDERReader.java,v 1.1 2007/10/15 12:49:56 cplattne Exp $
+ */
+public class SimpleDERReader
+{
+	private static final int CONSTRUCTED = 0x20;
+
+	byte[] buffer;
+	int pos;
+	int count;
+
+	public SimpleDERReader(byte[] b)
+	{
+		resetInput(b);
+	}
+	
+	public SimpleDERReader(byte[] b, int off, int len)
+	{
+		resetInput(b, off, len);
+	}
+
+	public void resetInput(byte[] b)
+	{
+		resetInput(b, 0, b.length);
+	}
+	
+	public void resetInput(byte[] b, int off, int len)
+	{
+		buffer = b;
+		pos = off;
+		count = len;
+	}
+
+	private byte readByte() throws IOException
+	{
+		if (count <= 0)
+			throw new IOException("DER byte array: out of data");
+		count--;
+		return buffer[pos++];
+	}
+
+	private byte[] readBytes(int len) throws IOException
+	{
+		if (len > count)
+			throw new IOException("DER byte array: out of data");
+
+		byte[] b = new byte[len];
+
+		System.arraycopy(buffer, pos, b, 0, len);
+
+		pos += len;
+		count -= len;
+
+		return b;
+	}
+
+	public int available()
+	{
+		return count;
+	}
+
+	private int readLength() throws IOException
+	{
+		int len = readByte() & 0xff;
+
+		if ((len & 0x80) == 0)
+			return len;
+
+		int remain = len & 0x7F;
+
+		if (remain == 0)
+			return -1;
+
+		len = 0;
+		
+		while (remain > 0)
+		{
+			len = len << 8;
+			len = len | (readByte() & 0xff);
+			remain--;
+		}
+
+		return len;
+	}
+
+	public int ignoreNextObject() throws IOException
+	{
+		int type = readByte() & 0xff;
+
+		int len = readLength();
+
+		if ((len < 0) || len > available())
+			throw new IOException("Illegal len in DER object (" + len  + ")");
+
+		readBytes(len);
+		
+		return type;
+	}
+	
+	public BigInteger readInt() throws IOException
+	{
+		int type = readByte() & 0xff;
+		
+		if (type != 0x02)
+			throw new IOException("Expected DER Integer, but found type " + type);
+		
+		int len = readLength();
+
+		if ((len < 0) || len > available())
+			throw new IOException("Illegal len in DER object (" + len  + ")");
+
+		byte[] b = readBytes(len);
+		
+		BigInteger bi = new BigInteger(b);
+		
+		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;
+		
+		if (type != 0x30)
+			throw new IOException("Expected DER Sequence, but found type " + type);
+		
+		int len = readLength();
+
+		if ((len < 0) || len > available())
+			throw new IOException("Illegal len in DER object (" + len  + ")");
+
+		byte[] b = readBytes(len);
+
+		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 && type != 0x03)
+			throw new IOException("Expected DER Octetstring, but found type " + type);
+		
+		int len = readLength();
+
+		if ((len < 0) || len > available())
+			throw new IOException("Illegal len in DER object (" + len  + ")");
+
+		byte[] b = readBytes(len);
+
+		return b;
+	}
+
+}