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 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

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package java.security;

/**

 * The Key interface is the top-level interface for all keys. It

 * defines the functionality shared by all key objects. All keys

 * have three characteristics:

 *

 * <UL>

 *

 * <LI>An Algorithm

 *

 * <P>This is the key algorithm for that key. The key algorithm is usually

 * an encryption or asymmetric operation algorithm (such as DSA or

 * RSA), which will work with those algorithms and with related

 * algorithms (such as MD5 with RSA, SHA-1 with RSA, Raw DSA, etc.)

 * The name of the algorithm of a key is obtained using the

 * {@link #getAlgorithm() getAlgorithm} method.

 *

 * <LI>An Encoded Form

 *

 * <P>This is an external encoded form for the key used when a standard

 * representation of the key is needed outside the Java Virtual Machine,

 * as when transmitting the key to some other party. The key

 * is encoded according to a standard format (such as

 * X.509 {@code SubjectPublicKeyInfo} or PKCS#8), and

 * is returned using the {@link #getEncoded() getEncoded} method.

 * Note: The syntax of the ASN.1 type {@code SubjectPublicKeyInfo}

 * is defined as follows:

 *

 * <pre>

 * SubjectPublicKeyInfo ::= SEQUENCE {

 *   algorithm AlgorithmIdentifier,

 *   subjectPublicKey BIT STRING }

 *

 * AlgorithmIdentifier ::= SEQUENCE {

 *   algorithm OBJECT IDENTIFIER,

 *   parameters ANY DEFINED BY algorithm OPTIONAL }

 * </pre>

 *

 * For more information, see

 * Internet X.509 Public Key Infrastructure Certificate and CRL Profile</a>.

 *

 * <LI>A Format

 *

 * <P>This is the name of the format of the encoded key. It is returned

 * by the {@link #getFormat() getFormat} method.

 *

 * </UL>

 *

 * Keys are generally obtained through key generators, certificates,

 * or various Identity classes used to manage keys.

 * Keys may also be obtained from key specifications (transparent

 * representations of the underlying key material) through the use of a key

 * factory (see {@link KeyFactory}).

 *

 * <p> A Key should use KeyRep as its serialized representation.

 * Note that a serialized Key may contain sensitive information

 * which should not be exposed in untrusted environments.  See the

 * <a href="../../../platform/serialization/spec/security.html">

 * Security Appendix</a>

 * of the Serialization Specification for more information.

 *

 * @see PublicKey

 * @see PrivateKey

 * @see KeyPair

 * @see KeyPairGenerator

 * @see KeyFactory

 * @see KeyRep

 * @see java.security.spec.KeySpec

 * @see Identity

 * @see Signer

 *

 * @author Benjamin Renaud

 */

public interface Key extends java.io.Serializable {

    // Declare serialVersionUID to be compatible with JDK1.1

   /**

    * The class fingerprint that is set to indicate

    * serialization compatibility with a previous

    * version of the class.

    */

    static final long serialVersionUID = 6603384152749567654L;

    /**

     * Returns the standard algorithm name for this key. For

     * example, "DSA" would indicate that this key is a DSA key.

     * See Appendix A in the <a href=

     * "../../../technotes/guides/security/crypto/CryptoSpec.html#AppA">

     * Java Cryptography Architecture API Specification &amp; Reference </a>

     * for information about standard algorithm names.

     *

     * @return the name of the algorithm associated with this key.

     */

    public String getAlgorithm();

    /**

     * Returns the name of the primary encoding format of this key,

     * or null if this key does not support encoding.

     * The primary encoding format is

     * named in terms of the appropriate ASN.1 data format, if an

     * ASN.1 specification for this key exists.

     * For example, the name of the ASN.1 data format for public

     * keys is <I>SubjectPublicKeyInfo</I>, as

     * defined by the X.509 standard; in this case, the returned format is

     * {@code "X.509"}. Similarly,

     * the name of the ASN.1 data format for private keys is

     * <I>PrivateKeyInfo</I>,

     * as defined by the PKCS #8 standard; in this case, the returned format is

     * {@code "PKCS#8"}.

     *

     * @return the primary encoding format of the key.

     */

    public String getFormat();

    /**

     * Returns the key in its primary encoding format, or null

     * if this key does not support encoding.

     *

     * @return the encoded key, or null if the key does not support

     * encoding.

     */

    public byte[] getEncoded();

}