001/* Signature.java --- Signature Class
002   Copyright (C) 1999, 2002, 2003, 2004  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.security;
040
041import gnu.java.lang.CPStringBuilder;
042
043import gnu.java.security.Engine;
044
045import java.lang.reflect.InvocationTargetException;
046import java.nio.ByteBuffer;
047import java.security.cert.Certificate;
048import java.security.cert.X509Certificate;
049import java.security.spec.AlgorithmParameterSpec;
050
051/**
052 * <code>Signature</code> is used to provide an interface to digital signature
053 * algorithms. Digital signatures provide authentication and data integrity of
054 * digital data.
055 *
056 * <p>The GNU provider provides the NIST standard DSA which uses DSA and SHA-1.
057 * It can be specified by SHA/DSA, SHA-1/DSA or its OID. If the RSA signature
058 * algorithm is provided then it could be MD2/RSA. MD5/RSA, or SHA-1/RSA. The
059 * algorithm must be specified because there is no default.</p>
060 *
061 * <p>Signature provides implementation-independent algorithms which are
062 * requested by the user through the <code>getInstance()<?code> methods. It can
063 * be requested by specifying just the algorithm name or by specifying both the
064 * algorithm name and provider name.</p>
065 *
066 * <p>The three phases of using <code>Signature</code> are:</p>
067 *
068 * <ol>
069 *   <li>Initializing:
070 *     <ul>
071 *       <li>It must be initialized with a private key for signing.</li>
072 *       <li>It must be initialized with a public key for verifying.</li>
073 *   </li>
074 *
075 *   <li>Updating:
076 *   <p>Update the bytes for signing or verifying with calls to update.</p>
077 *   </li>
078 *
079 *   <li>Signing or Verify the signature on the currently stored bytes by
080 *   calling sign or verify.</li>
081 * </ol>
082 *
083 * @author Mark Benvenuto  (ivymccough@worldnet.att.net)
084 */
085public abstract class Signature extends SignatureSpi
086{
087  /** Service name for signatures. */
088  private static final String SIGNATURE = "Signature";
089
090  /**
091   * Possible state value which signifies that this instance has not yet been
092   * initialized.
093   */
094  protected static final int UNINITIALIZED = 0;
095
096  /**
097   * Possible state value which signifies that this instance has been
098   * initialized for signing purposes.
099   */
100  protected static final int SIGN = 2;
101
102  /**
103   * Possible state value which signifies that this instance has been
104   * initialized for verification purposes.
105   */
106  protected static final int VERIFY = 3;
107
108  /** Current sate of this instance. */
109  protected int state = UNINITIALIZED;
110
111  private String algorithm;
112  Provider provider;
113
114  // Constructor.
115  // ------------------------------------------------------------------------
116
117  /**
118   * Constructs a new <code>Signature</code> instance for a designated digital
119   * signature algorithm.
120   *
121   * @param algorithm
122   *          the algorithm to use.
123   */
124  protected Signature(String algorithm)
125  {
126    this.algorithm = algorithm;
127    state = UNINITIALIZED;
128  }
129
130  /**
131   * Returns an instance of <code>Signature</code> representing the specified
132   * signature.
133   *
134   * @param algorithm the algorithm to use.
135   * @return a new instance repesenting the desired algorithm.
136   * @throws NoSuchAlgorithmException if the algorithm is not implemented by any
137   *           provider.
138   * @throws IllegalArgumentException if <code>algorithm</code> is
139   *           <code>null</code> or is an empty string.
140   */
141  public static Signature getInstance(String algorithm)
142      throws NoSuchAlgorithmException
143  {
144    Provider[] p = Security.getProviders();
145    NoSuchAlgorithmException lastException = null;
146    for (int i = 0; i < p.length; i++)
147      try
148        {
149          return getInstance(algorithm, p[i]);
150        }
151      catch (NoSuchAlgorithmException x)
152        {
153          lastException = x;
154        }
155    if (lastException != null)
156      throw lastException;
157    throw new NoSuchAlgorithmException(algorithm);
158  }
159
160  /**
161   * Returns an instance of <code>Signature</code> representing the specified
162   * signature from the named provider.
163   *
164   * @param algorithm the algorithm to use.
165   * @param provider the name of the provider to use.
166   * @return a new instance repesenting the desired algorithm.
167   * @throws NoSuchProviderException if the named provider was not found.
168   * @throws NoSuchAlgorithmException if the algorithm is not implemented by the
169   *           named provider.
170   * @throws IllegalArgumentException if either <code>algorithm</code> or
171   *           <code>provider</code> is <code>null</code> or empty.
172   */
173  public static Signature getInstance(String algorithm, String provider)
174      throws NoSuchAlgorithmException, NoSuchProviderException
175  {
176    if (provider == null)
177      throw new IllegalArgumentException("provider MUST NOT be null");
178    provider = provider.trim();
179    if (provider.length() == 0)
180      throw new IllegalArgumentException("provider MUST NOT be empty");
181    Provider p = Security.getProvider(provider);
182    if (p == null)
183      throw new NoSuchProviderException(provider);
184    return getInstance(algorithm, p);
185  }
186
187  /**
188   * Returns an instance of <code>Signature</code> representing the specified
189   * signature from the specified {@link Provider}.
190   *
191   * @param algorithm the algorithm to use.
192   * @param provider the {@link Provider} to use.
193   * @return a new instance repesenting the desired algorithm.
194   * @throws NoSuchAlgorithmException if the algorithm is not implemented by the
195   *           {@link Provider}.
196   * @throws IllegalArgumentException if either <code>algorithm</code> or
197   *           <code>provider</code> is <code>null</code>, or if
198   *           <code>algorithm</code> is an empty string.
199   */
200  public static Signature getInstance(String algorithm, Provider provider)
201    throws NoSuchAlgorithmException
202  {
203    CPStringBuilder sb = new CPStringBuilder("Signature algorithm [")
204        .append(algorithm).append("] from provider[")
205        .append(provider).append("] ");
206    Object o;
207    try
208      {
209        o = Engine.getInstance(SIGNATURE, algorithm, provider);
210      }
211    catch (InvocationTargetException x)
212      {
213        Throwable cause = x.getCause();
214        if (cause instanceof NoSuchAlgorithmException)
215          throw (NoSuchAlgorithmException) cause;
216        if (cause == null)
217          cause = x;
218        sb.append("could not be created");
219        NoSuchAlgorithmException y = new NoSuchAlgorithmException(sb.toString());
220        y.initCause(cause);
221        throw y;
222      }
223    Signature result;
224    if (o instanceof SignatureSpi)
225      result = new DummySignature((SignatureSpi) o, algorithm);
226    else if (o instanceof Signature)
227      {
228        result = (Signature) o;
229        result.algorithm = algorithm;
230      }
231    else
232      {
233        sb.append("is of an unexpected Type: ").append(o.getClass().getName());
234        throw new NoSuchAlgorithmException(sb.toString());
235      }
236    result.provider = provider;
237    return result;
238  }
239
240  /**
241   * Returns the {@link Provider} of this instance.
242   *
243   * @return the {@link Provider} of this instance.
244   */
245  public final Provider getProvider()
246  {
247    return provider;
248  }
249
250  /**
251   * Initializes this instance with the public key for verification purposes.
252   *
253   * @param publicKey
254   *          the public key to verify with.
255   * @throws InvalidKeyException
256   *           if the key is invalid.
257   */
258  public final void initVerify(PublicKey publicKey) throws InvalidKeyException
259  {
260    state = VERIFY;
261    engineInitVerify(publicKey);
262  }
263
264  /**
265   * Verify a signature with a designated {@link Certificate}. This is a FIPS
266   * 140-1 compatible method since it verifies a signature with a certificate.
267   *
268   * <p>If the {@link Certificate} is an X.509 one, has a <i>KeyUsage</i>
269   * parameter and that parameter indicates this key is not to be used for
270   * signing then an exception is thrown.</p>
271   *
272   * @param certificate
273   *          a {@link Certificate} containing a public key to verify with.
274   * @throws InvalidKeyException if the key is invalid.
275   */
276  public final void initVerify(Certificate certificate)
277    throws InvalidKeyException
278  {
279    state = VERIFY;
280    if (certificate.getType().equals("X509"))
281      {
282        X509Certificate cert = (X509Certificate) certificate;
283        boolean[]array = cert.getKeyUsage();
284        if (array != null && array[0] == false)
285          throw new InvalidKeyException(
286              "KeyUsage of this Certificate indicates it cannot be used for digital signing");
287      }
288    this.initVerify(certificate.getPublicKey());
289  }
290
291  /**
292   * Initializes this class with the private key for signing purposes.
293   *
294   * @param privateKey
295   *          the private key to sign with.
296   * @throws InvalidKeyException
297   *           if the key is invalid.
298   */
299  public final void initSign(PrivateKey privateKey) throws InvalidKeyException
300  {
301    state = SIGN;
302    engineInitSign(privateKey);
303  }
304
305  /**
306   * Initializes this class with the private key and source of randomness for
307   * signing purposes.
308   *
309   * @param privateKey
310   *          the private key to sign with.
311   * @param random
312   *          the {@link SecureRandom} to use.
313   * @throws InvalidKeyException
314   *           if the key is invalid.
315   */
316  public final void initSign(PrivateKey privateKey, SecureRandom random)
317    throws InvalidKeyException
318  {
319    state = SIGN;
320    engineInitSign(privateKey, random);
321  }
322
323  /**
324   * Returns the signature bytes of all the data fed to this instance. The
325   * format of the output depends on the underlying signature algorithm.
326   *
327   * @return the signature bytes.
328   * @throws SignatureException
329   *           if the engine is not properly initialized.
330   */
331  public final byte[] sign() throws SignatureException
332  {
333    if (state == SIGN)
334      return engineSign();
335    else
336      throw new SignatureException();
337  }
338
339  /**
340   * Generates signature bytes of all the data fed to this instance and stores
341   * it in the designated array. The format of the result depends on the
342   * underlying signature algorithm.
343   *
344   * <p>After calling this method, the instance is reset to its initial state
345   * and can then be used to generate additional signatures.</p>
346   *
347   * <p><b>IMPLEMENTATION NOTE:</b> Neither this method nor the GNU provider
348   * will return partial digests. If <code>len</code> is less than the
349   * signature length, this method will throw a {@link SignatureException}. If
350   * it is greater than or equal then it is ignored.</p>
351   *
352   * @param outbuf
353   *          array of bytes of where to store the resulting signature bytes.
354   * @param offset
355   *          the offset to start at in the array.
356   * @param len
357   *          the number of the bytes to use in the array.
358   * @return the real number of bytes used.
359   * @throws SignatureException
360   *           if the engine is not properly initialized.
361   * @since 1.2
362   */
363  public final int sign(byte[] outbuf, int offset, int len)
364    throws SignatureException
365  {
366    if (state == SIGN)
367      return engineSign(outbuf, offset, len);
368    else
369      throw new SignatureException();
370  }
371
372  /**
373   * Verifies a designated signature.
374   *
375   * @param signature
376   *          the signature bytes to verify.
377   * @return <code>true</code> if verified, <code>false</code> otherwise.
378   * @throws SignatureException
379   *           if the engine is not properly initialized or the signature does
380   *           not check.
381   */
382  public final boolean verify(byte[]signature) throws SignatureException
383  {
384    if (state == VERIFY)
385      return engineVerify(signature);
386    else
387      throw new SignatureException();
388  }
389
390  /**
391   * Verifies a designated signature.
392   *
393   * @param signature
394   *          the signature bytes to verify.
395   * @param offset
396   *          the offset to start at in the array.
397   * @param length
398   *          the number of the bytes to use from the array.
399   * @return <code>true</code> if verified, <code>false</code> otherwise.
400   * @throws IllegalArgumentException
401   *           if the <code>signature</code> byte array is <code>null</code>,
402   *           or the <code>offset</code> or <code>length</code> is less
403   *           than <code>0</code>, or the sum of the <code>offset</code>
404   *           and <code>length</code> is greater than the length of the
405   *           <code>signature</code> byte array.
406   * @throws SignatureException
407   *           if the engine is not properly initialized or the signature does
408   *           not check.
409   */
410  public final boolean verify(byte[] signature, int offset, int length)
411    throws SignatureException
412  {
413    if (state != VERIFY)
414      throw new SignatureException("illegal state");
415
416    if (signature == null)
417      throw new IllegalArgumentException("signature is null");
418    if (offset < 0)
419      throw new IllegalArgumentException("offset is less than 0");
420    if (length < 0)
421      throw new IllegalArgumentException("length is less than 0");
422    if (offset + length < signature.length)
423      throw new IllegalArgumentException("range is out of bounds");
424
425    return engineVerify(signature, offset, length);
426  }
427
428  /**
429   * Updates the data to be signed or verified with the specified byte.
430   *
431   * @param b
432   *          the byte to update with.
433   * @throws SignatureException
434   *           if the engine is not properly initialized.
435   */
436  public final void update(byte b) throws SignatureException
437  {
438    if (state != UNINITIALIZED)
439      engineUpdate(b);
440    else
441      throw new SignatureException();
442  }
443
444  /**
445   * Updates the data to be signed or verified with the specified bytes.
446   *
447   * @param data
448   *          the array of bytes to use.
449   * @throws SignatureException
450   *           if the engine is not properly initialized.
451   */
452  public final void update(byte[]data) throws SignatureException
453  {
454    if (state != UNINITIALIZED)
455      engineUpdate(data, 0, data.length);
456    else
457      throw new SignatureException();
458  }
459
460  /**
461   * Updates the data to be signed or verified with the specified bytes.
462   *
463   * @param data
464   *          an array of bytes to use.
465   * @param off
466   *          the offset to start at in the array.
467   * @param len
468   *          the number of bytes to use from the array.
469   * @throws SignatureException
470   *           if the engine is not properly initialized.
471   */
472  public final void update(byte[]data, int off, int len)
473    throws SignatureException
474  {
475    if (state != UNINITIALIZED)
476      engineUpdate(data, off, len);
477    else
478      throw new SignatureException();
479  }
480
481  /**
482   * Update this signature with the {@link java.nio.Buffer#remaining()}
483   * bytes of the input buffer.
484   *
485   * @param input The input buffer.
486   * @throws SignatureException If this instance was not properly
487   *  initialized.
488   */
489  public final void update(ByteBuffer input) throws SignatureException
490  {
491    if (state != UNINITIALIZED)
492      engineUpdate(input);
493    else
494      throw new SignatureException("not initialized");
495  }
496
497  /**
498   * Returns the name of the algorithm currently used. The names of algorithms
499   * are usually SHA/DSA or SHA/RSA.
500   *
501   * @return name of algorithm.
502   */
503  public final String getAlgorithm()
504  {
505    return algorithm;
506  }
507
508  /**
509   * Returns a rstring representation of this instance.
510   *
511   * @return a rstring representation of this instance.
512   */
513  public String toString()
514  {
515    return (algorithm + " Signature");
516  }
517
518  /**
519   * Sets the specified algorithm parameter to the specified value.
520   *
521   * @param param
522   *          the parameter name.
523   * @param value
524   *          the parameter value.
525   * @throws InvalidParameterException
526   *           if the parameter is invalid, the parameter is already set and
527   *           can not be changed, a security exception occured, etc.
528   * @deprecated use the other setParameter
529   */
530  public final void setParameter(String param, Object value)
531    throws InvalidParameterException
532  {
533    engineSetParameter(param, value);
534  }
535
536  /**
537   * Sets the signature engine with the specified {@link AlgorithmParameterSpec}.
538   *
539   * <p>By default, and unless overriden by the concrete SPI, this method always
540   * throws an {@link UnsupportedOperationException}.</p>
541   *
542   * @param params
543   *          the parameters to use for intializing this instance.
544   * @throws InvalidParameterException
545   *           if the parameter is invalid, the parameter is already set and
546   *           cannot be changed, a security exception occured, etc.
547   */
548  public final void setParameter(AlgorithmParameterSpec params)
549    throws InvalidAlgorithmParameterException
550  {
551    engineSetParameter(params);
552  }
553
554  /**
555   * Return the parameters of the algorithm used in this instance as an
556   * {@link AlgorithmParameters}.
557   *
558   * @return the parameters used with this instance, or <code>null</code> if
559   *         this instance does not use any parameters.
560   */
561  public final AlgorithmParameters getParameters()
562  {
563    return engineGetParameters();
564  }
565
566  /**
567   * Returns the value for the specified algorithm parameter.
568   *
569   * @param param
570   *          the parameter name.
571   * @return the parameter value.
572   * @throws InvalidParameterException
573   *           if the parameter is invalid.
574   * @deprecated use the other getParameter
575   */
576  public final Object getParameter(String param)
577    throws InvalidParameterException
578  {
579    return engineGetParameter(param);
580  }
581
582  /**
583   * Returns a clone of this instance.
584   *
585   * @return a clone of this instace.
586   * @throws CloneNotSupportedException
587   *           if the implementation does not support cloning.
588   */
589  public Object clone() throws CloneNotSupportedException
590  {
591    return super.clone();
592  }
593}