1 /*
2 * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation. Oracle designates this
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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
32 /**
33 * This class is used as an opaque representation of cryptographic parameters.
34 *
35 * <p>An {@code AlgorithmParameters} object for managing the parameters
36 * for a particular algorithm can be obtained by
37 * calling one of the {@code getInstance} factory methods
38 * (static methods that return instances of a given class).
39 *
40 * <p>Once an {@code AlgorithmParameters} object is obtained, it must be
41 * initialized via a call to {@code init}, using an appropriate parameter
42 * specification or parameter encoding.
43 *
44 * <p>A transparent parameter specification is obtained from an
45 * {@code AlgorithmParameters} object via a call to
46 * {@code getParameterSpec}, and a byte encoding of the parameters is
47 * obtained via a call to {@code getEncoded}.
48 *
49 * <p> Every implementation of the Java platform is required to support the
50 * following standard {@code AlgorithmParameters} algorithms:
51 * <ul>
52 * <li>{@code AES}</li>
53 * <li>{@code DES}</li>
54 * <li>{@code DESede}</li>
55 * <li>{@code DiffieHellman}</li>
56 * <li>{@code DSA}</li>
57 * </ul>
58 * These algorithms are described in the <a href=
59 * "{@docRoot}/../technotes/guides/security/StandardNames.html#AlgorithmParameters">
60 * AlgorithmParameters section</a> of the
61 * Java Cryptography Architecture Standard Algorithm Name Documentation.
62 * Consult the release documentation for your implementation to see if any
63 * other algorithms are supported.
64 *
65 * @author Jan Luehe
66 *
67 *
68 * @see java.security.spec.AlgorithmParameterSpec
69 * @see java.security.spec.DSAParameterSpec
70 * @see KeyPairGenerator
71 *
72 * @since 1.2
73 */
74
75 public class AlgorithmParameters {
76
77 // The provider
78 private Provider provider;
79
80 // The provider implementation (delegate)
81 private AlgorithmParametersSpi paramSpi;
82
83 // The algorithm
84 private String algorithm;
85
86 // Has this object been initialized?
87 private boolean initialized = false;
88
89 /**
90 * Creates an AlgorithmParameters object.
91 *
92 * @param paramSpi the delegate
93 * @param provider the provider
94 * @param algorithm the algorithm
95 */
96 protected AlgorithmParameters(AlgorithmParametersSpi paramSpi,
97 Provider provider, String algorithm)
98 {
99 this.paramSpi = paramSpi;
100 this.provider = provider;
101 this.algorithm = algorithm;
102 }
103
104 /**
105 * Returns the name of the algorithm associated with this parameter object.
106 *
107 * @return the algorithm name.
108 */
109 public final String getAlgorithm() {
110 return this.algorithm;
111 }
112
113 /**
114 * Returns a parameter object for the specified algorithm.
115 *
116 * <p> This method traverses the list of registered security Providers,
117 * starting with the most preferred Provider.
118 * A new AlgorithmParameters object encapsulating the
119 * AlgorithmParametersSpi implementation from the first
120 * Provider that supports the specified algorithm is returned.
121 *
122 * <p> Note that the list of registered providers may be retrieved via
123 * the {@link Security#getProviders() Security.getProviders()} method.
124 *
125 * <p> The returned parameter object must be initialized via a call to
126 * {@code init}, using an appropriate parameter specification or
127 * parameter encoding.
128 *
129 * @implNote
130 * The JDK Reference Implementation additionally uses the
131 * {@code jdk.security.provider.preferred}
132 * {@link Security#getProperty(String) Security} property to determine
133 * the preferred provider order for the specified algorithm. This
134 * may be different than the order of providers returned by
135 * {@link Security#getProviders() Security.getProviders()}.
136 *
137 * @param algorithm the name of the algorithm requested.
138 * See the AlgorithmParameters section in the <a href=
139 * "{@docRoot}/../technotes/guides/security/StandardNames.html#AlgorithmParameters">
140 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
141 * for information about standard algorithm names.
142 *
143 * @return the new parameter object.
144 *
145 * @exception NoSuchAlgorithmException if no Provider supports an
146 * AlgorithmParametersSpi implementation for the
147 * specified algorithm.
148 *
149 * @see Provider
150 */
151 public static AlgorithmParameters getInstance(String algorithm)
152 throws NoSuchAlgorithmException {
153 try {
154 Object[] objs = Security.getImpl(algorithm, "AlgorithmParameters",
155 (String)null);
156 return new AlgorithmParameters((AlgorithmParametersSpi)objs[0],
157 (Provider)objs[1],
158 algorithm);
159 } catch(NoSuchProviderException e) {
160 throw new NoSuchAlgorithmException(algorithm + " not found");
161 }
162 }
163
164 /**
165 * Returns a parameter object for the specified algorithm.
166 *
167 * <p> A new AlgorithmParameters object encapsulating the
168 * AlgorithmParametersSpi implementation from the specified provider
169 * is returned. The specified provider must be registered
170 * in the security provider list.
171 *
172 * <p> Note that the list of registered providers may be retrieved via
173 * the {@link Security#getProviders() Security.getProviders()} method.
174 *
175 * <p>The returned parameter object must be initialized via a call to
176 * {@code init}, using an appropriate parameter specification or
177 * parameter encoding.
178 *
179 * @param algorithm the name of the algorithm requested.
180 * See the AlgorithmParameters section in the <a href=
181 * "{@docRoot}/../technotes/guides/security/StandardNames.html#AlgorithmParameters">
182 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
183 * for information about standard algorithm names.
184 *
185 * @param provider the name of the provider.
186 *
187 * @return the new parameter object.
188 *
189 * @exception NoSuchAlgorithmException if an AlgorithmParametersSpi
190 * implementation for the specified algorithm is not
191 * available from the specified provider.
192 *
193 * @exception NoSuchProviderException if the specified provider is not
194 * registered in the security provider list.
195 *
196 * @exception IllegalArgumentException if the provider name is null
197 * or empty.
198 *
199 * @see Provider
200 */
201 public static AlgorithmParameters getInstance(String algorithm,
202 String provider)
203 throws NoSuchAlgorithmException, NoSuchProviderException
204 {
205 if (provider == null || provider.length() == 0)
206 throw new IllegalArgumentException("missing provider");
207 Object[] objs = Security.getImpl(algorithm, "AlgorithmParameters",
208 provider);
209 return new AlgorithmParameters((AlgorithmParametersSpi)objs[0],
210 (Provider)objs[1],
211 algorithm);
212 }
213
214 /**
215 * Returns a parameter object for the specified algorithm.
216 *
217 * <p> A new AlgorithmParameters object encapsulating the
218 * AlgorithmParametersSpi implementation from the specified Provider
219 * object is returned. Note that the specified Provider object
220 * does not have to be registered in the provider list.
221 *
222 * <p>The returned parameter object must be initialized via a call to
223 * {@code init}, using an appropriate parameter specification or
224 * parameter encoding.
225 *
226 * @param algorithm the name of the algorithm requested.
227 * See the AlgorithmParameters section in the <a href=
228 * "{@docRoot}/../technotes/guides/security/StandardNames.html#AlgorithmParameters">
229 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
230 * for information about standard algorithm names.
231 *
232 * @param provider the name of the provider.
233 *
234 * @return the new parameter object.
235 *
236 * @exception NoSuchAlgorithmException if an AlgorithmParameterGeneratorSpi
237 * implementation for the specified algorithm is not available
238 * from the specified Provider object.
239 *
240 * @exception IllegalArgumentException if the provider is null.
241 *
242 * @see Provider
243 *
244 * @since 1.4
245 */
246 public static AlgorithmParameters getInstance(String algorithm,
247 Provider provider)
248 throws NoSuchAlgorithmException
249 {
250 if (provider == null)
251 throw new IllegalArgumentException("missing provider");
252 Object[] objs = Security.getImpl(algorithm, "AlgorithmParameters",
253 provider);
254 return new AlgorithmParameters((AlgorithmParametersSpi)objs[0],
255 (Provider)objs[1],
256 algorithm);
257 }
258
259 /**
260 * Returns the provider of this parameter object.
261 *
262 * @return the provider of this parameter object
263 */
264 public final Provider getProvider() {
265 return this.provider;
266 }
267
268 /**
269 * Initializes this parameter object using the parameters
270 * specified in {@code paramSpec}.
271 *
272 * @param paramSpec the parameter specification.
273 *
274 * @exception InvalidParameterSpecException if the given parameter
275 * specification is inappropriate for the initialization of this parameter
276 * object, or if this parameter object has already been initialized.
277 */
278 public final void init(AlgorithmParameterSpec paramSpec)
279 throws InvalidParameterSpecException
280 {
281 if (this.initialized)
282 throw new InvalidParameterSpecException("already initialized");
283 paramSpi.engineInit(paramSpec);
284 this.initialized = true;
285 }
286
287 /**
288 * Imports the specified parameters and decodes them according to the
289 * primary decoding format for parameters. The primary decoding
290 * format for parameters is ASN.1, if an ASN.1 specification for this type
291 * of parameters exists.
292 *
293 * @param params the encoded parameters.
294 *
295 * @exception IOException on decoding errors, or if this parameter object
296 * has already been initialized.
297 */
298 public final void init(byte[] params) throws IOException {
299 if (this.initialized)
300 throw new IOException("already initialized");
301 paramSpi.engineInit(params);
302 this.initialized = true;
303 }
304
305 /**
306 * Imports the parameters from {@code params} and decodes them
307 * according to the specified decoding scheme.
308 * If {@code format} is null, the
309 * primary decoding format for parameters is used. The primary decoding
310 * format is ASN.1, if an ASN.1 specification for these parameters
311 * exists.
312 *
313 * @param params the encoded parameters.
314 *
315 * @param format the name of the decoding scheme.
316 *
317 * @exception IOException on decoding errors, or if this parameter object
318 * has already been initialized.
319 */
320 public final void init(byte[] params, String format) throws IOException {
321 if (this.initialized)
322 throw new IOException("already initialized");
323 paramSpi.engineInit(params, format);
324 this.initialized = true;
325 }
326
327 /**
328 * Returns a (transparent) specification of this parameter object.
329 * {@code paramSpec} identifies the specification class in which
330 * the parameters should be returned. It could, for example, be
331 * {@code DSAParameterSpec.class}, to indicate that the
332 * parameters should be returned in an instance of the
333 * {@code DSAParameterSpec} class.
334 *
335 * @param <T> the type of the parameter specification to be returrned
336 * @param paramSpec the specification class in which
337 * the parameters should be returned.
338 *
339 * @return the parameter specification.
340 *
341 * @exception InvalidParameterSpecException if the requested parameter
342 * specification is inappropriate for this parameter object, or if this
343 * parameter object has not been initialized.
344 */
345 public final <T extends AlgorithmParameterSpec>
346 T getParameterSpec(Class<T> paramSpec)
347 throws InvalidParameterSpecException
348 {
349 if (this.initialized == false) {
350 throw new InvalidParameterSpecException("not initialized");
351 }
352 return paramSpi.engineGetParameterSpec(paramSpec);
353 }
354
355 /**
356 * Returns the parameters in their primary encoding format.
357 * The primary encoding format for parameters is ASN.1, if an ASN.1
358 * specification for this type of parameters exists.
359 *
360 * @return the parameters encoded using their primary encoding format.
361 *
362 * @exception IOException on encoding errors, or if this parameter object
363 * has not been initialized.
364 */
365 public final byte[] getEncoded() throws IOException
366 {
367 if (this.initialized == false) {
368 throw new IOException("not initialized");
369 }
370 return paramSpi.engineGetEncoded();
371 }
372
373 /**
374 * Returns the parameters encoded in the specified scheme.
375 * If {@code format} is null, the
376 * primary encoding format for parameters is used. The primary encoding
377 * format is ASN.1, if an ASN.1 specification for these parameters
378 * exists.
379 *
380 * @param format the name of the encoding format.
381 *
382 * @return the parameters encoded using the specified encoding scheme.
383 *
384 * @exception IOException on encoding errors, or if this parameter object
385 * has not been initialized.
386 */
387 public final byte[] getEncoded(String format) throws IOException
388 {
389 if (this.initialized == false) {
390 throw new IOException("not initialized");
391 }
392 return paramSpi.engineGetEncoded(format);
393 }
394
395 /**
396 * Returns a formatted string describing the parameters.
397 *
398 * @return a formatted string describing the parameters, or null if this
399 * parameter object has not been initialized.
400 */
401 public final String toString() {
402 if (this.initialized == false) {
403 return null;
404 }
405 return paramSpi.engineToString();
406 }
407 }