diff options
Diffstat (limited to 'src/com/trilead/ssh2/crypto/SimpleDERReader.java')
| -rw-r--r-- | src/com/trilead/ssh2/crypto/SimpleDERReader.java | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/src/com/trilead/ssh2/crypto/SimpleDERReader.java b/src/com/trilead/ssh2/crypto/SimpleDERReader.java new file mode 100644 index 0000000..55c6c6a --- /dev/null +++ b/src/com/trilead/ssh2/crypto/SimpleDERReader.java @@ -0,0 +1,160 @@ +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
+{
+ 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 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 byte[] readOctetString() throws IOException
+ {
+ int type = readByte() & 0xff;
+
+ if (type != 0x04)
+ 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;
+ }
+
+}
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