Subversion Repositories openrisc

/* DERReader.java --

   Copyright (C) 1999, 2006  Free Software Foundation, Inc.

This file is a part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2 of the License, or (at

your option) any later version.

GNU Classpath is distributed in the hope that it will be useful, but

WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

General Public License for more details.

You should have received a copy of the GNU General Public License

along with GNU Classpath; if not, write to the Free Software

Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301

USA

Linking this library statically or dynamically with other modules is

making a combined work based on this library.  Thus, the terms and

conditions of the GNU General Public License cover the whole

combination.

As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

executable, regardless of the license terms of these independent

modules, and to copy and distribute the resulting executable under

terms of your choice, provided that you also meet, for each linked

independent module, the terms and conditions of the license of that

module.  An independent module is a module which is not derived from

or based on this library.  If you modify this library, you may extend

this exception to your version of the library, but you are not

obligated to do so.  If you do not wish to do so, delete this

exception statement from your version.  */

package gnu.javax.crypto.jce.params;

import java.math.BigInteger;

class DERReader

{

  byte source[];

  int pos;

  static final int UNIVERSAL = 1;

  static final int APPLICATION = 2;

  static final int CONTEXT_SPECIFIC = 3;

  static final int PRIVATE = 4;

  public DERReader()

  {

    source = null;

    pos = 0;

  }

  public DERReader(byte source[])

  {

    init(source);

  }

  public void init(String source)

  {

    init(source.getBytes());

  }

  public void init(byte source[])

  {

    this.source = source;

    pos = 0;

  }

  public boolean hasMorePrimitives()

  {

    return pos < source.length;

  }

  public BigInteger getBigInteger() throws DEREncodingException

  {

    return new BigInteger(getPrimitive());

  }

  // Reads Primitive, definite-length method

  private byte[] getPrimitive() throws DEREncodingException

  {

    int tmp = pos;

    // Read Identifier

    byte identifier = source[tmp++];

    if ((0x20 & identifier) != 0)

      throw new DEREncodingException();

    int type = translateLeadIdentifierByte(identifier);

    // get tag

    int tag = (0x1f & identifier);

    // get length

    byte len = source[tmp]; // may be length of length parameter

    long length = 0x7f & len;

    int i;

    if ((0x80 & len) != 0)

      {

        len &= 0x7f;

        // get length here

        length = 0;

        for (i = 0; i < len; i++)

          {

            tmp++;

            length <<= 8;

            length += (source[tmp] < 0) ? (256 + source[tmp]) : source[tmp];

          }

        tmp++;

      }

    else

      tmp++;

    byte tmpb[] = new byte[(int) length];

    System.arraycopy(source, tmp, tmpb, 0, (int) length);

    pos = (int) (tmp + length);

    return tmpb;

  }

  private int translateLeadIdentifierByte(byte b)

  {

    if ((0x3f & b) == b)

      return UNIVERSAL;

    else if ((0x7f & b) == b)

      return APPLICATION;

    else if ((0xbf & b) == b)

      return CONTEXT_SPECIFIC;

    else

      return PRIVATE;

  }

  private int getIdentifier(int tpos)

  {

    while ((0x80 & source[tpos]) != 0)

      tpos++;

    return tpos;

  }

}