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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

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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,

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 *

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package java.security.spec;

/**

 * This immutable class specifies the set of parameters used for

 * generating DSA parameters as specified in

 * <a href="http://csrc.nist.gov/publications/fips/fips186-3/fips_186-3.pdf">FIPS 186-3 Digital Signature Standard (DSS)</a>.

 *

 * @see AlgorithmParameterSpec

 *

 * @since 1.8

 */

public final class DSAGenParameterSpec implements AlgorithmParameterSpec {

    private final int pLen;

    private final int qLen;

    private final int seedLen;

    /**

     * Creates a domain parameter specification for DSA parameter

     * generation using {@code primePLen} and {@code subprimeQLen}.

     * The value of {@code subprimeQLen} is also used as the default

     * length of the domain parameter seed in bits.

     * @param primePLen the desired length of the prime P in bits.

     * @param subprimeQLen the desired length of the sub-prime Q in bits.

     * or {@code subprimeQLen} is illegal per the specification of

     * FIPS 186-3.

     */

    public DSAGenParameterSpec(int primePLen, int subprimeQLen) {

        this(primePLen, subprimeQLen, subprimeQLen);

    }

    /**

     * Creates a domain parameter specification for DSA parameter

     * generation using {@code primePLen}, {@code subprimeQLen},

     * and {@code seedLen}.

     * @param primePLen the desired length of the prime P in bits.

     * @param subprimeQLen the desired length of the sub-prime Q in bits.

     * @param seedLen the desired length of the domain parameter seed in bits,

     * shall be equal to or greater than {@code subprimeQLen}.

     * {@code subprimeQLen}, or {@code seedLen} is illegal per the

     * specification of FIPS 186-3.

     */

    public DSAGenParameterSpec(int primePLen, int subprimeQLen, int seedLen) {

        switch (primePLen) {

        case 1024:

            if (subprimeQLen != 160) {

                throw new IllegalArgumentException

                    ("subprimeQLen must be 160 when primePLen=1024");

            }

            break;

        case 2048:

            if (subprimeQLen != 224 && subprimeQLen != 256) {

               throw new IllegalArgumentException

                   ("subprimeQLen must be 224 or 256 when primePLen=2048");

            }

            break;

        case 3072:

            if (subprimeQLen != 256) {

                throw new IllegalArgumentException

                    ("subprimeQLen must be 256 when primePLen=3072");

            }

            break;

        default:

            throw new IllegalArgumentException

                ("primePLen must be 1024, 2048, or 3072");

        }

        if (seedLen < subprimeQLen) {

            throw new IllegalArgumentException

                ("seedLen must be equal to or greater than subprimeQLen");

        }

        this.pLen = primePLen;

        this.qLen = subprimeQLen;

        this.seedLen = seedLen;

    }

    /**

     * Returns the desired length of the prime P of the

     * to-be-generated DSA domain parameters in bits.

     * @return the length of the prime P.

     */

    public int getPrimePLength() {

        return pLen;

    }

    /**

     * Returns the desired length of the sub-prime Q of the

     * to-be-generated DSA domain parameters in bits.

     * @return the length of the sub-prime Q.

     */

    public int getSubprimeQLength() {

        return qLen;

    }

    /**

     * Returns the desired length of the domain parameter seed in bits.

     * @return the length of the domain parameter seed.

     */

    public int getSeedLength() {

        return seedLen;

    }

}