1 /*

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

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

     4  *

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

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

     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.

    10  *

    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).

    16  *

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

    18  * 2 along with this work; if not, write to the Free Software Foundation,

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

    20  *

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

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

    23  * questions.

    24  */

    25 

    26 package sun.security.ssl;

    27 

    28 import java.io.IOException;

    29 import java.nio.ByteBuffer;

    30 import java.security.GeneralSecurityException;

    31 import java.security.spec.AlgorithmParameterSpec;

    32 import javax.crypto.SecretKey;

    33 import javax.net.ssl.SSLHandshakeException;

    34 

    35 final class SSLBasicKeyDerivation implements SSLKeyDerivation {

    36     private final String hashAlg;

    37     private final SecretKey secret;

    38     private final byte[] hkdfInfo;

    39 

    40     SSLBasicKeyDerivation(SecretKey secret, String hashAlg,

    41             byte[] label, byte[] context, int length) {

    42         this.hashAlg = hashAlg.replace("-", "");

    43         this.secret = secret;

    44         this.hkdfInfo = createHkdfInfo(label, context, length);

    45     }

    46 

    47     @Override

    48     public SecretKey deriveKey(String algorithm,

    49             AlgorithmParameterSpec keySpec) throws IOException {

    50         try {

    51             HKDF hkdf = new HKDF(hashAlg);

    52             return hkdf.expand(secret, hkdfInfo,

    53                     ((SecretSizeSpec)keySpec).length, algorithm);

    54         } catch (GeneralSecurityException gse) {

    55             throw (SSLHandshakeException) new SSLHandshakeException(

    56                 "Could not generate secret").initCause(gse);

    57         }

    58     }

    59 

    60     private static byte[] createHkdfInfo(

    61             byte[] label, byte[] context, int length) {

    62         byte[] info = new byte[4 + label.length + context.length];

    63         ByteBuffer m = ByteBuffer.wrap(info);

    64         try {

    65             Record.putInt16(m, length);

    66             Record.putBytes8(m, label);

    67             Record.putBytes8(m, context);

    68         } catch (IOException ioe) {

    69             // unlikely

    70         }

    71         return info;

    72     }

    73 

    74     static class SecretSizeSpec implements AlgorithmParameterSpec {

    75         final int length;

    76 

    77         SecretSizeSpec(int length) {

    78             this.length = length;

    79         }

    80     }

    81 }