gcc/libjava/classpath/gnu/javax/crypto/pad/PKCS1_V1_5.java

/* PKCS1_V1_5.java --
   Copyright (C) 2003, 2006, 2010 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.

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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
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permission to link this library with independent modules to produce an
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this exception to your version of the library, but you are not
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exception statement from your version.  */


package gnu.javax.crypto.pad;

import gnu.java.security.Configuration;
import gnu.java.security.Registry;
import gnu.java.security.sig.rsa.EME_PKCS1_V1_5;
import gnu.java.security.util.PRNG;
import gnu.java.security.util.Util;

import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * A padding algorithm implementation of the EME-PKCS1-V1.5 encoding/decoding
 * algorithm as described in section 7.2 of RFC-3447. This is effectively an
 * <i>Adapter</i> over an instance of {@link EME_PKCS1_V1_5} initialised with
 * the RSA public shared modulus length (in bytes).
 * <p>
 * References:
 * <ol>
 * <li><a href="http://www.ietf.org/rfc/rfc3447.txt">Public-Key Cryptography
 * Standards (PKCS) #1:</a><br>
 * RSA Cryptography Specifications Version 2.1.<br>
 * Jakob Jonsson and Burt Kaliski.</li>
 * </ol>
 *
 * @see EME_PKCS1_V1_5
 */
public class PKCS1_V1_5
    extends BasePad
{
  private static final Logger log = Configuration.DEBUG ?
                        Logger.getLogger(PKCS1_V1_5.class.getName()) : null;
  private EME_PKCS1_V1_5 codec;

  /**
   * Trivial package-private constructor for use by the <i>Factory</i> class.
   *
   * @see PadFactory
   */
  PKCS1_V1_5()
  {
    super(Registry.EME_PKCS1_V1_5_PAD);
  }

  public void setup()
  {
    codec = EME_PKCS1_V1_5.getInstance(blockSize);
  }

  public byte[] pad(final byte[] in, final int offset, final int length)
  {
    final byte[] M = new byte[length];
    System.arraycopy(in, offset, M, 0, length);
    final byte[] EM = codec.encode(M);
    final byte[] result = new byte[blockSize - length];
    System.arraycopy(EM, 0, result, 0, result.length);
    if (Configuration.DEBUG)
      log.fine("padding: 0x" + Util.toString(result));
    return result;
  }

  public int unpad(final byte[] in, final int offset, final int length)
      throws WrongPaddingException
  {
    final byte[] EM = new byte[length];
    System.arraycopy(in, offset, EM, 0, length);
    final int result = length - codec.decode(EM).length;
    if (Configuration.DEBUG)
      log.fine("padding length: " + String.valueOf(result));
    return result;
  }

  public boolean selfTest()
  {
    final int[] mLen = new int[] { 16, 20, 32, 48, 64 };
    final byte[] M = new byte[mLen[mLen.length - 1]];
    PRNG.getInstance().nextBytes(M);
    final byte[] EM = new byte[1024];
    byte[] p;
    int bs, i, j;
    for (bs = 256; bs < 1025; bs += 256)
      {
        init(bs);
        for (i = 0; i < mLen.length; i++)
          {
            j = mLen[i];
            p = pad(M, 0, j);
            if (j + p.length != blockSize)
              {
                if (Configuration.DEBUG)
                  log.log(Level.SEVERE,
                          "Length of padded text MUST be a multiple of "
                          + blockSize, new RuntimeException(name()));
                return false;
              }
            System.arraycopy(p, 0, EM, 0, p.length);
            System.arraycopy(M, 0, EM, p.length, j);
            try
              {
                if (p.length != unpad(EM, 0, blockSize))
                  {
                    if (Configuration.DEBUG)
                      log.log(Level.SEVERE, "Failed symmetric operation",
                              new RuntimeException(name()));
                    return false;
                  }
              }
            catch (WrongPaddingException x)
              {
                if (Configuration.DEBUG)
                  log.throwing(this.getClass().getName(), "selfTest", x);
                return false;
              }
          }
        reset();
      }
    return true;
  }
}