/*

 * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.

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

 *

 * This code is free software; you can redistribute it and/or modify it

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

 * published by the Free Software Foundation.

 *

 * 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.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.test.lib;

import java.security.*;

import java.security.spec.*;

import java.util.*;

/*

 * Utility class used by various Signature related regression tests for

 * common functions such as generating the list of to-be-tested algorithms

 * based on key size, etc. Currently, this is mostly needed by RSA

 * signatures.

 */

public class SigTestUtil {

    public enum SignatureType {

        RSA("RSA"),

        RSASSA_PSS("RSASSA-PSS")

        ;

        private String keyAlg;

        SignatureType(String keyAlg) {

            this.keyAlg = keyAlg;

        }

        @Override

        public String toString() {

            return keyAlg;

        }

    }    

    // collection of all supported digest algorithms

    // note that the entries are ordered by required key sizes

    private static final String[] DIGEST_ALGS = {

        "SHA-512",

        "SHA-384",

        "SHA-256",

        "SHA-512/256",

        "SHA-224",

        "SHA-512/224",

        "SHA-1",

        "MD2", "MD5" // these aren't supported by RSA PSS

    };

    // indice for message digest algorithms lookup

    // may need to be adjusted if new algorithms are added

    private static final int PKCS1_5_INDEX_768 = 0;

    private static final int PKCS1_5_INDEX_512 = 2;

    private static final int PKCS1_5_INDEX_END = DIGEST_ALGS.length;

    private static final int PSS_INDEX_2048 = 0;

    private static final int PSS_INDEX_1024 = 1;

    private static final int PSS_INDEX_768 = 2;

    private static final int PSS_INDEX_512 = 4;

    private static final int PSS_INDEX_END = 7;

    public static Iterable<String> getDigestAlgorithms(SignatureType type,

            int keysize) throws RuntimeException {

        // initialize to all, then trim based on key size

        List<String> result = new ArrayList<>(Arrays.asList(DIGEST_ALGS));

        int index = 0;

        switch (type) {

        case RSA:

            if (keysize >= 768) {

                index = PKCS1_5_INDEX_768;

            } else if (keysize >= 512) {

                index = PKCS1_5_INDEX_512;

            } else {

                throw new RuntimeException("Keysize too small: " + keysize);

            }

            result = result.subList(index, PKCS1_5_INDEX_END);

            break;

        case RSASSA_PSS:

            if (keysize >= 2048) {

                index = PSS_INDEX_2048;

            } else if (keysize >= 1024) {

                index = PSS_INDEX_1024;

            } else if (keysize >= 768) {

                index = PSS_INDEX_768;

            } else if (keysize >= 512) {

                index = PSS_INDEX_512;

            } else {

                throw new RuntimeException("Keysize too small: " + keysize);

            }

            result = result.subList(index, PSS_INDEX_END);

            break;

        default:

            // XXX maybe just return result instead of error out?

            throw new RuntimeException("Unsupported signature type: " + type);

        }

        return result;

    }

    public static AlgorithmParameterSpec generateDefaultParameter(

            SignatureType type, String mdAlg) throws RuntimeException {

        // only RSASSA-PSS signature uses parameters

        switch (type) {

        case RSASSA_PSS:

            try {

                MessageDigest md = MessageDigest.getInstance(mdAlg);

                return new PSSParameterSpec(mdAlg, "MGF1",

                    new MGF1ParameterSpec(mdAlg), md.getDigestLength(),

                    PSSParameterSpec.TRAILER_FIELD_BC);

            } catch (Exception e) {

                throw new RuntimeException(e);

            }

        default:

            return null;

        }

    }

    public static String generateSigAlg(SignatureType type,

            String mdAlg) throws RuntimeException {

        switch (type) {

        case RSA:

            int idx = mdAlg.indexOf("-");

            if (idx != -1) {

                mdAlg = mdAlg.substring(0, idx) + mdAlg.substring(idx+1);

            }

            return mdAlg + "with" + type.toString();

        case RSASSA_PSS:

            return type.toString();

        default:

            throw new RuntimeException("Unsupported signature type " + type );

        }

    }

}