Java example source code file (SupportedEllipticCurvesExtension.java)

This example Java source code file (SupportedEllipticCurvesExtension.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arbitrary_char2, arbitrary_prime, default, hashmap, invalid, ioexception, k\-163, named_curve_oid_table, net, nist, override, p\-384, ssl, string, stringbuilder, supportedellipticcurvesextension, util

The SupportedEllipticCurvesExtension.java Java example source code

/*
 * Copyright (c) 2006, 2012, 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.  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.
 *
 * 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 sun.security.ssl;

import java.io.IOException;
import java.security.spec.ECParameterSpec;
import java.util.HashMap;
import java.util.Map;

import javax.net.ssl.SSLProtocolException;

final class SupportedEllipticCurvesExtension extends HelloExtension {

    // the extension value to send in the ClientHello message
    static final SupportedEllipticCurvesExtension DEFAULT;

    private static final boolean fips;

    static {
        int[] ids;
        fips = SunJSSE.isFIPS();
        if (fips == false) {
            ids = new int[] {
                // NIST curves first
                // prefer NIST P-256, rest in order of increasing key length
                23, 1, 3, 19, 21, 6, 7, 9, 10, 24, 11, 12, 25, 13, 14,
                // non-NIST curves
                15, 16, 17, 2, 18, 4, 5, 20, 8, 22,
            };
        } else {
            ids = new int[] {
                // same as above, but allow only NIST curves in FIPS mode
                23, 1, 3, 19, 21, 6, 7, 9, 10, 24, 11, 12, 25, 13, 14,
            };
        }
        DEFAULT = new SupportedEllipticCurvesExtension(ids);
    }

    private final int[] curveIds;

    private SupportedEllipticCurvesExtension(int[] curveIds) {
        super(ExtensionType.EXT_ELLIPTIC_CURVES);
        this.curveIds = curveIds;
    }

    SupportedEllipticCurvesExtension(HandshakeInStream s, int len)
            throws IOException {
        super(ExtensionType.EXT_ELLIPTIC_CURVES);
        int k = s.getInt16();
        if (((len & 1) != 0) || (k + 2 != len)) {
            throw new SSLProtocolException("Invalid " + type + " extension");
        }
        curveIds = new int[k >> 1];
        for (int i = 0; i < curveIds.length; i++) {
            curveIds[i] = s.getInt16();
        }
    }

    boolean contains(int index) {
        for (int curveId : curveIds) {
            if (index == curveId) {
                return true;
            }
        }
        return false;
    }

    // Return a reference to the internal curveIds array.
    // The caller must NOT modify the contents.
    int[] curveIds() {
        return curveIds;
    }

    @Override
    int length() {
        return 6 + (curveIds.length << 1);
    }

    @Override
    void send(HandshakeOutStream s) throws IOException {
        s.putInt16(type.id);
        int k = curveIds.length << 1;
        s.putInt16(k + 2);
        s.putInt16(k);
        for (int curveId : curveIds) {
            s.putInt16(curveId);
        }
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("Extension " + type + ", curve names: {");
        boolean first = true;
        for (int curveId : curveIds) {
            if (first) {
                first = false;
            } else {
                sb.append(", ");
            }
            // first check if it is a known named curve, then try other cases.
            String oid = getCurveOid(curveId);
            if (oid != null) {
                ECParameterSpec spec = JsseJce.getECParameterSpec(oid);
                // this toString() output will look nice for the current
                // implementation of the ECParameterSpec class in the Sun
                // provider, but may not look good for other implementations.
                if (spec != null) {
                    sb.append(spec.toString().split(" ")[0]);
                } else {
                    sb.append(oid);
                }
            } else if (curveId == ARBITRARY_PRIME) {
                sb.append("arbitrary_explicit_prime_curves");
            } else if (curveId == ARBITRARY_CHAR2) {
                sb.append("arbitrary_explicit_char2_curves");
            } else {
                sb.append("unknown curve " + curveId);
            }
        }
        sb.append("}");
        return sb.toString();
    }

    // Test whether we support the curve with the given index.
    static boolean isSupported(int index) {
        if ((index <= 0) || (index >= NAMED_CURVE_OID_TABLE.length)) {
            return false;
        }
        if (fips == false) {
            // in non-FIPS mode, we support all valid indices
            return true;
        }
        return DEFAULT.contains(index);
    }

    static int getCurveIndex(ECParameterSpec params) {
        String oid = JsseJce.getNamedCurveOid(params);
        if (oid == null) {
            return -1;
        }
        Integer n = curveIndices.get(oid);
        return (n == null) ? -1 : n;
    }

    static String getCurveOid(int index) {
        if ((index > 0) && (index < NAMED_CURVE_OID_TABLE.length)) {
            return NAMED_CURVE_OID_TABLE[index];
        }
        return null;
    }

    private final static int ARBITRARY_PRIME = 0xff01;
    private final static int ARBITRARY_CHAR2 = 0xff02;

    // See sun.security.ec.NamedCurve for the OIDs
    private final static String[] NAMED_CURVE_OID_TABLE = new String[] {
        null,                   //  (0) unused
        "1.3.132.0.1",          //  (1) sect163k1, NIST K-163
        "1.3.132.0.2",          //  (2) sect163r1
        "1.3.132.0.15",         //  (3) sect163r2, NIST B-163
        "1.3.132.0.24",         //  (4) sect193r1
        "1.3.132.0.25",         //  (5) sect193r2
        "1.3.132.0.26",         //  (6) sect233k1, NIST K-233
        "1.3.132.0.27",         //  (7) sect233r1, NIST B-233
        "1.3.132.0.3",          //  (8) sect239k1
        "1.3.132.0.16",         //  (9) sect283k1, NIST K-283
        "1.3.132.0.17",         // (10) sect283r1, NIST B-283
        "1.3.132.0.36",         // (11) sect409k1, NIST K-409
        "1.3.132.0.37",         // (12) sect409r1, NIST B-409
        "1.3.132.0.38",         // (13) sect571k1, NIST K-571
        "1.3.132.0.39",         // (14) sect571r1, NIST B-571
        "1.3.132.0.9",          // (15) secp160k1
        "1.3.132.0.8",          // (16) secp160r1
        "1.3.132.0.30",         // (17) secp160r2
        "1.3.132.0.31",         // (18) secp192k1
        "1.2.840.10045.3.1.1",  // (19) secp192r1, NIST P-192
        "1.3.132.0.32",         // (20) secp224k1
        "1.3.132.0.33",         // (21) secp224r1, NIST P-224
        "1.3.132.0.10",         // (22) secp256k1
        "1.2.840.10045.3.1.7",  // (23) secp256r1, NIST P-256
        "1.3.132.0.34",         // (24) secp384r1, NIST P-384
        "1.3.132.0.35",         // (25) secp521r1, NIST P-521
    };

    private final static Map<String,Integer> curveIndices;

    static {
        curveIndices = new HashMap<String,Integer>();
        for (int i = 1; i < NAMED_CURVE_OID_TABLE.length; i++) {
            curveIndices.put(NAMED_CURVE_OID_TABLE[i], i);
        }
    }

}