1 /*
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   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
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
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  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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  23  * questions.
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  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 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}/../specs/security/standard-names.html#algorithmparameters-algorithms">
  60  * AlgorithmParameters section</a> of the
  61  * Java Security Standard Algorithm Names Specification.
  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}/../specs/security/standard-names.html#algorithmparameters-algorithms">
 140      * Java Security Standard Algorithm Names Specification</a>
 141      * for information about standard algorithm names.
 142      *
 143      * @return the new parameter object
 144      *
 145      * @throws NoSuchAlgorithmException if no {@code Provider} supports an
 146      *         {@code AlgorithmParametersSpi} implementation for the
 147      *         specified algorithm
 148      *
 149      * @throws NullPointerException if {@code algorithm} is {@code null}
 150      *
 151      * @see Provider
 152      */
 153     public static AlgorithmParameters getInstance(String algorithm)
 154     throws NoSuchAlgorithmException {
 155         Objects.requireNonNull(algorithm, "null algorithm name");
 156         try {
 157             Object[] objs = Security.getImpl(algorithm, "AlgorithmParameters",
 158                                              (String)null);
 159             return new AlgorithmParameters((AlgorithmParametersSpi)objs[0],
 160                                            (Provider)objs[1],
 161                                            algorithm);
 162         } catch(NoSuchProviderException e) {
 163             throw new NoSuchAlgorithmException(algorithm + " not found");
 164         }
 165     }
 166 
 167     /**
 168      * Returns a parameter object for the specified algorithm.
 169      *
 170      * <p> A new AlgorithmParameters object encapsulating the
 171      * AlgorithmParametersSpi implementation from the specified provider
 172      * is returned.  The specified provider must be registered
 173      * in the security provider list.
 174      *
 175      * <p> Note that the list of registered providers may be retrieved via
 176      * the {@link Security#getProviders() Security.getProviders()} method.
 177      *
 178      * <p>The returned parameter object must be initialized via a call to
 179      * {@code init}, using an appropriate parameter specification or
 180      * parameter encoding.
 181      *
 182      * @param algorithm the name of the algorithm requested.
 183      * See the AlgorithmParameters section in the <a href=
 184      * "{@docRoot}/../specs/security/standard-names.html#algorithmparameters-algorithms">
 185      * Java Security Standard Algorithm Names Specification</a>
 186      * for information about standard algorithm names.
 187      *
 188      * @param provider the name of the provider.
 189      *
 190      * @return the new parameter object
 191      *
 192      * @throws IllegalArgumentException if the provider name is {@code null}
 193      *         or empty
 194      *
 195      * @throws NoSuchAlgorithmException if an {@code AlgorithmParametersSpi}
 196      *         implementation for the specified algorithm is not
 197      *         available from the specified provider
 198      *
 199      * @throws NoSuchProviderException if the specified provider is not
 200      *         registered in the security provider list
 201      *
 202      * @throws NullPointerException if {@code algorithm} is {@code null}
 203      *
 204      * @see Provider
 205      */
 206     public static AlgorithmParameters getInstance(String algorithm,
 207                                                   String provider)
 208         throws NoSuchAlgorithmException, NoSuchProviderException
 209     {
 210         Objects.requireNonNull(algorithm, "null algorithm name");
 211         if (provider == null || provider.isEmpty())
 212             throw new IllegalArgumentException("missing provider");
 213         Object[] objs = Security.getImpl(algorithm, "AlgorithmParameters",
 214                                          provider);
 215         return new AlgorithmParameters((AlgorithmParametersSpi)objs[0],
 216                                        (Provider)objs[1],
 217                                        algorithm);
 218     }
 219 
 220     /**
 221      * Returns a parameter object for the specified algorithm.
 222      *
 223      * <p> A new AlgorithmParameters object encapsulating the
 224      * AlgorithmParametersSpi implementation from the specified Provider
 225      * object is returned.  Note that the specified Provider object
 226      * does not have to be registered in the provider list.
 227      *
 228      * <p>The returned parameter object must be initialized via a call to
 229      * {@code init}, using an appropriate parameter specification or
 230      * parameter encoding.
 231      *
 232      * @param algorithm the name of the algorithm requested.
 233      * See the AlgorithmParameters section in the <a href=
 234      * "{@docRoot}/../specs/security/standard-names.html#algorithmparameters-algorithms">
 235      * Java Security Standard Algorithm Names Specification</a>
 236      * for information about standard algorithm names.
 237      *
 238      * @param provider the name of the provider.
 239      *
 240      * @return the new parameter object
 241      *
 242      * @throws IllegalArgumentException if the provider is {@code null}
 243      *
 244      * @throws NoSuchAlgorithmException if an
 245      *         {@code AlgorithmParameterGeneratorSpi}
 246      *         implementation for the specified algorithm is not available
 247      *         from the specified {@code Provider} object
 248      *
 249      * @throws NullPointerException if {@code algorithm} is {@code null}
 250      *
 251      * @see Provider
 252      *
 253      * @since 1.4
 254      */
 255     public static AlgorithmParameters getInstance(String algorithm,
 256                                                   Provider provider)
 257         throws NoSuchAlgorithmException
 258     {
 259         Objects.requireNonNull(algorithm, "null algorithm name");
 260         if (provider == null)
 261             throw new IllegalArgumentException("missing provider");
 262         Object[] objs = Security.getImpl(algorithm, "AlgorithmParameters",
 263                                          provider);
 264         return new AlgorithmParameters((AlgorithmParametersSpi)objs[0],
 265                                        (Provider)objs[1],
 266                                        algorithm);
 267     }
 268 
 269     /**
 270      * Returns the provider of this parameter object.
 271      *
 272      * @return the provider of this parameter object
 273      */
 274     public final Provider getProvider() {
 275         return this.provider;
 276     }
 277 
 278     /**
 279      * Initializes this parameter object using the parameters
 280      * specified in {@code paramSpec}.
 281      *
 282      * @param paramSpec the parameter specification.
 283      *
 284      * @throws    InvalidParameterSpecException if the given parameter
 285      * specification is inappropriate for the initialization of this parameter
 286      * object, or if this parameter object has already been initialized.
 287      */
 288     public final void init(AlgorithmParameterSpec paramSpec)
 289         throws InvalidParameterSpecException
 290     {
 291         if (this.initialized)
 292             throw new InvalidParameterSpecException("already initialized");
 293         paramSpi.engineInit(paramSpec);
 294         this.initialized = true;
 295     }
 296 
 297     /**
 298      * Imports the specified parameters and decodes them according to the
 299      * primary decoding format for parameters. The primary decoding
 300      * format for parameters is ASN.1, if an ASN.1 specification for this type
 301      * of parameters exists.
 302      *
 303      * @param params the encoded parameters.
 304      *
 305      * @throws    IOException on decoding errors, or if this parameter object
 306      * has already been initialized.
 307      */
 308     public final void init(byte[] params) throws IOException {
 309         if (this.initialized)
 310             throw new IOException("already initialized");
 311         paramSpi.engineInit(params);
 312         this.initialized = true;
 313     }
 314 
 315     /**
 316      * Imports the parameters from {@code params} and decodes them
 317      * according to the specified decoding scheme.
 318      * If {@code format} is null, the
 319      * primary decoding format for parameters is used. The primary decoding
 320      * format is ASN.1, if an ASN.1 specification for these parameters
 321      * exists.
 322      *
 323      * @param params the encoded parameters.
 324      *
 325      * @param format the name of the decoding scheme.
 326      *
 327      * @throws    IOException on decoding errors, or if this parameter object
 328      * has already been initialized.
 329      */
 330     public final void init(byte[] params, String format) throws IOException {
 331         if (this.initialized)
 332             throw new IOException("already initialized");
 333         paramSpi.engineInit(params, format);
 334         this.initialized = true;
 335     }
 336 
 337     /**
 338      * Returns a (transparent) specification of this parameter object.
 339      * {@code paramSpec} identifies the specification class in which
 340      * the parameters should be returned. It could, for example, be
 341      * {@code DSAParameterSpec.class}, to indicate that the
 342      * parameters should be returned in an instance of the
 343      * {@code DSAParameterSpec} class.
 344      *
 345      * @param <T> the type of the parameter specification to be returrned
 346      * @param paramSpec the specification class in which
 347      * the parameters should be returned.
 348      *
 349      * @return the parameter specification.
 350      *
 351      * @throws    InvalidParameterSpecException if the requested parameter
 352      * specification is inappropriate for this parameter object, or if this
 353      * parameter object has not been initialized.
 354      */
 355     public final <T extends AlgorithmParameterSpec>
 356         T getParameterSpec(Class<T> paramSpec)
 357         throws InvalidParameterSpecException
 358     {
 359         if (this.initialized == false) {
 360             throw new InvalidParameterSpecException("not initialized");
 361         }
 362         return paramSpi.engineGetParameterSpec(paramSpec);
 363     }
 364 
 365     /**
 366      * Returns the parameters in their primary encoding format.
 367      * The primary encoding format for parameters is ASN.1, if an ASN.1
 368      * specification for this type of parameters exists.
 369      *
 370      * @return the parameters encoded using their primary encoding format.
 371      *
 372      * @throws    IOException on encoding errors, or if this parameter object
 373      * has not been initialized.
 374      */
 375     public final byte[] getEncoded() throws IOException
 376     {
 377         if (this.initialized == false) {
 378             throw new IOException("not initialized");
 379         }
 380         return paramSpi.engineGetEncoded();
 381     }
 382 
 383     /**
 384      * Returns the parameters encoded in the specified scheme.
 385      * If {@code format} is null, the
 386      * primary encoding format for parameters is used. The primary encoding
 387      * format is ASN.1, if an ASN.1 specification for these parameters
 388      * exists.
 389      *
 390      * @param format the name of the encoding format.
 391      *
 392      * @return the parameters encoded using the specified encoding scheme.
 393      *
 394      * @throws    IOException on encoding errors, or if this parameter object
 395      * has not been initialized.
 396      */
 397     public final byte[] getEncoded(String format) throws IOException
 398     {
 399         if (this.initialized == false) {
 400             throw new IOException("not initialized");
 401         }
 402         return paramSpi.engineGetEncoded(format);
 403     }
 404 
 405     /**
 406      * Returns a formatted string describing the parameters.
 407      *
 408      * @return a formatted string describing the parameters, or null if this
 409      * parameter object has not been initialized.
 410      */
 411     public final String toString() {
 412         if (this.initialized == false) {
 413             return null;
 414         }
 415         return paramSpi.engineToString();
 416     }
 417 }