1 /*
2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
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24 */
25
26 package java.security;
27
28 import java.io.*;
29 import java.security.spec.AlgorithmParameterSpec;
30 import java.security.spec.InvalidParameterSpecException;
31 import java.util.Objects;
32
33 /**
34 * This class is used as an opaque representation of cryptographic parameters.
35 *
36 * <p>An {@code AlgorithmParameters} object for managing the parameters
37 * for a particular algorithm can be obtained by
38 * calling one of the {@code getInstance} factory methods
39 * (static methods that return instances of a given class).
40 *
41 * <p>Once an {@code AlgorithmParameters} object is obtained, it must be
42 * initialized via a call to {@code init}, using an appropriate parameter
43 * specification or parameter encoding.
44 *
45 * <p>A transparent parameter specification is obtained from an
46 * {@code AlgorithmParameters} object via a call to
47 * {@code getParameterSpec}, and a byte encoding of the parameters is
48 * obtained via a call to {@code getEncoded}.
49 *
50 * <p> Every implementation of the Java platform is required to support the
51 * following standard {@code AlgorithmParameters} algorithms:
52 * <ul>
53 * <li>{@code AES}</li>
54 * <li>{@code DES}</li>
55 * <li>{@code DESede}</li>
56 * <li>{@code DiffieHellman}</li>
57 * <li>{@code DSA}</li>
58 * </ul>
59 * These algorithms are described in the <a href=
60 * "{@docRoot}/../specs/security/standard-names.html#algorithmparameters-algorithms">
61 * AlgorithmParameters section</a> of the
62 * Java Security Standard Algorithm Names Specification.
63 * Consult the release documentation for your implementation to see if any
64 * other algorithms are supported.
65 *
66 * @author Jan Luehe
67 *
68 *
69 * @see java.security.spec.AlgorithmParameterSpec
70 * @see java.security.spec.DSAParameterSpec
71 * @see KeyPairGenerator
72 *
73 * @since 1.2
74 */
75
76 public class AlgorithmParameters {
77
78 // The provider
79 private Provider provider;
80
81 // The provider implementation (delegate)
82 private AlgorithmParametersSpi paramSpi;
83
84 // The algorithm
85 private String algorithm;
86
87 // Has this object been initialized?
88 private boolean initialized = false;
89
90 /**
91 * Creates an AlgorithmParameters object.
92 *
93 * @param paramSpi the delegate
94 * @param provider the provider
95 * @param algorithm the algorithm
96 */
97 protected AlgorithmParameters(AlgorithmParametersSpi paramSpi,
98 Provider provider, String algorithm)
99 {
100 this.paramSpi = paramSpi;
101 this.provider = provider;
102 this.algorithm = algorithm;
103 }
104
105 /**
106 * Returns the name of the algorithm associated with this parameter object.
107 *
108 * @return the algorithm name.
109 */
110 public final String getAlgorithm() {
111 return this.algorithm;
112 }
113
114 /**
115 * Returns a parameter object for the specified algorithm.
116 *
117 * <p> This method traverses the list of registered security Providers,
118 * starting with the most preferred Provider.
119 * A new AlgorithmParameters object encapsulating the
120 * AlgorithmParametersSpi implementation from the first
121 * Provider that supports the specified algorithm is returned.
122 *
123 * <p> Note that the list of registered providers may be retrieved via
124 * the {@link Security#getProviders() Security.getProviders()} method.
125 *
126 * <p> The returned parameter object must be initialized via a call to
127 * {@code init}, using an appropriate parameter specification or
128 * parameter encoding.
129 *
130 * @implNote
131 * The JDK Reference Implementation additionally uses the
132 * {@code jdk.security.provider.preferred}
133 * {@link Security#getProperty(String) Security} property to determine
134 * the preferred provider order for the specified algorithm. This
135 * may be different than the order of providers returned by
136 * {@link Security#getProviders() Security.getProviders()}.
137 *
138 * @param algorithm the name of the algorithm requested.
139 * See the AlgorithmParameters section in the <a href=
140 * "{@docRoot}/../specs/security/standard-names.html#algorithmparameters-algorithms">
141 * Java Security Standard Algorithm Names Specification</a>
142 * for information about standard algorithm names.
143 *
144 * @return the new parameter object
145 *
146 * @throws NoSuchAlgorithmException if no {@code Provider} supports an
147 * {@code AlgorithmParametersSpi} implementation for the
148 * specified algorithm
149 *
150 * @throws NullPointerException if {@code algorithm} is {@code null}
151 *
152 * @see Provider
153 */
154 public static AlgorithmParameters getInstance(String algorithm)
155 throws NoSuchAlgorithmException {
156 Objects.requireNonNull(algorithm, "null algorithm name");
157 try {
158 Object[] objs = Security.getImpl(algorithm, "AlgorithmParameters",
159 (String)null);
160 return new AlgorithmParameters((AlgorithmParametersSpi)objs[0],
161 (Provider)objs[1],
162 algorithm);
163 } catch(NoSuchProviderException e) {
164 throw new NoSuchAlgorithmException(algorithm + " not found");
165 }
166 }
167
168 /**
169 * Returns a parameter object for the specified algorithm.
170 *
171 * <p> A new AlgorithmParameters object encapsulating the
172 * AlgorithmParametersSpi implementation from the specified provider
173 * is returned. The specified provider must be registered
174 * in the security provider list.
175 *
176 * <p> Note that the list of registered providers may be retrieved via
177 * the {@link Security#getProviders() Security.getProviders()} method.
178 *
179 * <p>The returned parameter object must be initialized via a call to
180 * {@code init}, using an appropriate parameter specification or
181 * parameter encoding.
182 *
183 * @param algorithm the name of the algorithm requested.
184 * See the AlgorithmParameters section in the <a href=
185 * "{@docRoot}/../specs/security/standard-names.html#algorithmparameters-algorithms">
186 * Java Security Standard Algorithm Names Specification</a>
187 * for information about standard algorithm names.
188 *
189 * @param provider the name of the provider.
190 *
191 * @return the new parameter object
192 *
193 * @throws IllegalArgumentException if the provider name is {@code null}
194 * or empty
195 *
196 * @throws NoSuchAlgorithmException if an {@code AlgorithmParametersSpi}
197 * implementation for the specified algorithm is not
198 * available from the specified provider
199 *
200 * @throws NoSuchProviderException if the specified provider is not
201 * registered in the security provider list
202 *
203 * @throws NullPointerException if {@code algorithm} is {@code null}
204 *
205 * @see Provider
206 */
207 public static AlgorithmParameters getInstance(String algorithm,
208 String provider)
209 throws NoSuchAlgorithmException, NoSuchProviderException
210 {
211 Objects.requireNonNull(algorithm, "null algorithm name");
212 if (provider == null || provider.length() == 0)
213 throw new IllegalArgumentException("missing provider");
214 Object[] objs = Security.getImpl(algorithm, "AlgorithmParameters",
215 provider);
216 return new AlgorithmParameters((AlgorithmParametersSpi)objs[0],
217 (Provider)objs[1],
218 algorithm);
219 }
220
221 /**
222 * Returns a parameter object for the specified algorithm.
223 *
224 * <p> A new AlgorithmParameters object encapsulating the
225 * AlgorithmParametersSpi implementation from the specified Provider
226 * object is returned. Note that the specified Provider object
227 * does not have to be registered in the provider list.
228 *
229 * <p>The returned parameter object must be initialized via a call to
230 * {@code init}, using an appropriate parameter specification or
231 * parameter encoding.
232 *
233 * @param algorithm the name of the algorithm requested.
234 * See the AlgorithmParameters section in the <a href=
235 * "{@docRoot}/../specs/security/standard-names.html#algorithmparameters-algorithms">
236 * Java Security Standard Algorithm Names Specification</a>
237 * for information about standard algorithm names.
238 *
239 * @param provider the name of the provider.
240 *
241 * @return the new parameter object
242 *
243 * @throws IllegalArgumentException if the provider is {@code null}
244 *
245 * @throws NoSuchAlgorithmException if an
246 * {@code AlgorithmParameterGeneratorSpi}
247 * implementation for the specified algorithm is not available
248 * from the specified {@code Provider} object
249 *
250 * @throws NullPointerException if {@code algorithm} is {@code null}
251 *
252 * @see Provider
253 *
254 * @since 1.4
255 */
256 public static AlgorithmParameters getInstance(String algorithm,
257 Provider provider)
258 throws NoSuchAlgorithmException
259 {
260 Objects.requireNonNull(algorithm, "null algorithm name");
261 if (provider == null)
262 throw new IllegalArgumentException("missing provider");
263 Object[] objs = Security.getImpl(algorithm, "AlgorithmParameters",
264 provider);
265 return new AlgorithmParameters((AlgorithmParametersSpi)objs[0],
266 (Provider)objs[1],
267 algorithm);
268 }
269
270 /**
271 * Returns the provider of this parameter object.
272 *
273 * @return the provider of this parameter object
274 */
275 public final Provider getProvider() {
276 return this.provider;
277 }
278
279 /**
280 * Initializes this parameter object using the parameters
281 * specified in {@code paramSpec}.
282 *
283 * @param paramSpec the parameter specification.
284 *
285 * @exception InvalidParameterSpecException if the given parameter
286 * specification is inappropriate for the initialization of this parameter
287 * object, or if this parameter object has already been initialized.
288 */
289 public final void init(AlgorithmParameterSpec paramSpec)
290 throws InvalidParameterSpecException
291 {
292 if (this.initialized)
293 throw new InvalidParameterSpecException("already initialized");
294 paramSpi.engineInit(paramSpec);
295 this.initialized = true;
296 }
297
298 /**
299 * Imports the specified parameters and decodes them according to the
300 * primary decoding format for parameters. The primary decoding
301 * format for parameters is ASN.1, if an ASN.1 specification for this type
302 * of parameters exists.
303 *
304 * @param params the encoded parameters.
305 *
306 * @exception IOException on decoding errors, or if this parameter object
307 * has already been initialized.
308 */
309 public final void init(byte[] params) throws IOException {
310 if (this.initialized)
311 throw new IOException("already initialized");
312 paramSpi.engineInit(params);
313 this.initialized = true;
314 }
315
316 /**
317 * Imports the parameters from {@code params} and decodes them
318 * according to the specified decoding scheme.
319 * If {@code format} is null, the
320 * primary decoding format for parameters is used. The primary decoding
321 * format is ASN.1, if an ASN.1 specification for these parameters
322 * exists.
323 *
324 * @param params the encoded parameters.
325 *
326 * @param format the name of the decoding scheme.
327 *
328 * @exception IOException on decoding errors, or if this parameter object
329 * has already been initialized.
330 */
331 public final void init(byte[] params, String format) throws IOException {
332 if (this.initialized)
333 throw new IOException("already initialized");
334 paramSpi.engineInit(params, format);
335 this.initialized = true;
336 }
337
338 /**
339 * Returns a (transparent) specification of this parameter object.
340 * {@code paramSpec} identifies the specification class in which
341 * the parameters should be returned. It could, for example, be
342 * {@code DSAParameterSpec.class}, to indicate that the
343 * parameters should be returned in an instance of the
344 * {@code DSAParameterSpec} class.
345 *
346 * @param <T> the type of the parameter specification to be returrned
347 * @param paramSpec the specification class in which
348 * the parameters should be returned.
349 *
350 * @return the parameter specification.
351 *
352 * @exception InvalidParameterSpecException if the requested parameter
353 * specification is inappropriate for this parameter object, or if this
354 * parameter object has not been initialized.
355 */
356 public final <T extends AlgorithmParameterSpec>
357 T getParameterSpec(Class<T> paramSpec)
358 throws InvalidParameterSpecException
359 {
360 if (this.initialized == false) {
361 throw new InvalidParameterSpecException("not initialized");
362 }
363 return paramSpi.engineGetParameterSpec(paramSpec);
364 }
365
366 /**
367 * Returns the parameters in their primary encoding format.
368 * The primary encoding format for parameters is ASN.1, if an ASN.1
369 * specification for this type of parameters exists.
370 *
371 * @return the parameters encoded using their primary encoding format.
372 *
373 * @exception IOException on encoding errors, or if this parameter object
374 * has not been initialized.
375 */
376 public final byte[] getEncoded() throws IOException
377 {
378 if (this.initialized == false) {
379 throw new IOException("not initialized");
380 }
381 return paramSpi.engineGetEncoded();
382 }
383
384 /**
385 * Returns the parameters encoded in the specified scheme.
386 * If {@code format} is null, the
387 * primary encoding format for parameters is used. The primary encoding
388 * format is ASN.1, if an ASN.1 specification for these parameters
389 * exists.
390 *
391 * @param format the name of the encoding format.
392 *
393 * @return the parameters encoded using the specified encoding scheme.
394 *
395 * @exception IOException on encoding errors, or if this parameter object
396 * has not been initialized.
397 */
398 public final byte[] getEncoded(String format) throws IOException
399 {
400 if (this.initialized == false) {
401 throw new IOException("not initialized");
402 }
403 return paramSpi.engineGetEncoded(format);
404 }
405
406 /**
407 * Returns a formatted string describing the parameters.
408 *
409 * @return a formatted string describing the parameters, or null if this
410 * parameter object has not been initialized.
411 */
412 public final String toString() {
413 if (this.initialized == false) {
414 return null;
415 }
416 return paramSpi.engineToString();
417 }
418 }