/*

 * 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.  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

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package sun.security.ssl;

import java.io.IOException;

import java.math.BigInteger;

import java.nio.ByteBuffer;

import java.security.CryptoPrimitive;

import java.security.GeneralSecurityException;

import java.security.InvalidKeyException;

import java.security.KeyFactory;

import java.security.NoSuchAlgorithmException;

import java.security.Signature;

import java.security.SignatureException;

import java.security.interfaces.RSAPublicKey;

import java.security.spec.RSAPublicKeySpec;

import java.text.MessageFormat;

import java.util.EnumSet;

import java.util.Locale;

import sun.security.ssl.RSAKeyExchange.EphemeralRSACredentials;

import sun.security.ssl.RSAKeyExchange.EphemeralRSAPossession;

import sun.security.ssl.SSLHandshake.HandshakeMessage;

import sun.security.ssl.X509Authentication.X509Credentials;

import sun.security.ssl.X509Authentication.X509Possession;

import sun.security.util.HexDumpEncoder;

/**

 * Pack of the ServerKeyExchange handshake message.

 */

final class RSAServerKeyExchange {

    static final SSLConsumer rsaHandshakeConsumer =

        new RSAServerKeyExchangeConsumer();

    static final HandshakeProducer rsaHandshakeProducer =

        new RSAServerKeyExchangeProducer();

    /**

     * The ephemeral RSA ServerKeyExchange handshake message.

     *

     * Used for RSA_EXPORT, SSL 3.0 and TLS 1.0 only.

     */

    private static final

            class RSAServerKeyExchangeMessage extends HandshakeMessage {

        // public key encapsulated in this message

        private final byte[] modulus;     // 1 to 2^16 - 1 bytes

        private final byte[] exponent;    // 1 to 2^16 - 1 bytes

        // signature bytes, none-null as no anonymous RSA key exchange.

        private final byte[] paramsSignature;

        private RSAServerKeyExchangeMessage(HandshakeContext handshakeContext,

                X509Possession x509Possession,

                EphemeralRSAPossession rsaPossession) throws IOException {

            super(handshakeContext);

            // This happens in server side only.

            ServerHandshakeContext shc =

                    (ServerHandshakeContext)handshakeContext;

            RSAPublicKey publicKey = rsaPossession.popPublicKey;

            RSAPublicKeySpec spec = JsseJce.getRSAPublicKeySpec(publicKey);

            this.modulus = Utilities.toByteArray(spec.getModulus());

            this.exponent = Utilities.toByteArray(spec.getPublicExponent());

            byte[] signature = null;

            try {

                Signature signer = RSASignature.getInstance();

                signer.initSign(x509Possession.popPrivateKey,

                        shc.sslContext.getSecureRandom());

                updateSignature(signer,

                          shc.clientHelloRandom.randomBytes,

                          shc.serverHelloRandom.randomBytes);

                signature = signer.sign();

            } catch (NoSuchAlgorithmException |

                    InvalidKeyException | SignatureException ex) {

                shc.conContext.fatal(Alert.INTERNAL_ERROR,

                        "Failed to sign ephemeral RSA parameters", ex);

            }

            this.paramsSignature = signature;

        }

        RSAServerKeyExchangeMessage(HandshakeContext handshakeContext,

                ByteBuffer m) throws IOException {

            super(handshakeContext);

            // This happens in client side only.

            ClientHandshakeContext chc =

                    (ClientHandshakeContext)handshakeContext;

            this.modulus = Record.getBytes16(m);

            this.exponent = Record.getBytes16(m);

            this.paramsSignature = Record.getBytes16(m);

            X509Credentials x509Credentials = null;

            for (SSLCredentials cd : chc.handshakeCredentials) {

                if (cd instanceof X509Credentials) {

                    x509Credentials = (X509Credentials)cd;

                    break;

                }

            }

            if (x509Credentials == null) {

                chc.conContext.fatal(Alert.ILLEGAL_PARAMETER,

                    "No RSA credentials negotiated for server key exchange");

            }

            try {

                Signature signer = RSASignature.getInstance();

                signer.initVerify(x509Credentials.popPublicKey);

                updateSignature(signer,

                          chc.clientHelloRandom.randomBytes,

                          chc.serverHelloRandom.randomBytes);

                if (!signer.verify(paramsSignature)) {

                    chc.conContext.fatal(Alert.HANDSHAKE_FAILURE,

                        "Invalid signature of RSA ServerKeyExchange message");

                }

            } catch (NoSuchAlgorithmException |

                    InvalidKeyException | SignatureException ex) {

                chc.conContext.fatal(Alert.INTERNAL_ERROR,

                    "Failed to sign ephemeral RSA parameters", ex);

            }

        }

        @Override

        SSLHandshake handshakeType() {

            return SSLHandshake.SERVER_KEY_EXCHANGE;

        }

        @Override

        int messageLength() {

            return 6 + modulus.length + exponent.length

                   + paramsSignature.length;

        }

        @Override

        void send(HandshakeOutStream hos) throws IOException {

            hos.putBytes16(modulus);

            hos.putBytes16(exponent);

            hos.putBytes16(paramsSignature);

        }

        @Override

        public String toString() {

            MessageFormat messageFormat = new MessageFormat(

                "\"RSA ServerKeyExchange\": '{'\n" +

                "  \"parameters\": '{'\n" +

                "    \"rsa_modulus\": '{'\n" +

                "{0}\n" +

                "    '}',\n" +

                "    \"rsa_exponent\": '{'\n" +

                "{1}\n" +

                "    '}'\n" +

                "  '}',\n" +

                "  \"digital signature\":  '{'\n" +

                "    \"signature\": '{'\n" +

                "{2}\n" +

                "    '}',\n" +

                "  '}'\n" +

                "'}'",

                Locale.ENGLISH);

            HexDumpEncoder hexEncoder = new HexDumpEncoder();

            Object[] messageFields = {

                Utilities.indent(

                        hexEncoder.encodeBuffer(modulus), "      "),

                Utilities.indent(

                        hexEncoder.encodeBuffer(exponent), "      "),

                Utilities.indent(

                        hexEncoder.encodeBuffer(paramsSignature), "      ")

            };

            return messageFormat.format(messageFields);

        }

        /*

         * Hash the nonces and the ephemeral RSA public key.

         */

        private void updateSignature(Signature signature,

                byte[] clntNonce, byte[] svrNonce) throws SignatureException {

            signature.update(clntNonce);

            signature.update(svrNonce);

            signature.update((byte)(modulus.length >> 8));

            signature.update((byte)(modulus.length & 0x0ff));

            signature.update(modulus);

            signature.update((byte)(exponent.length >> 8));

            signature.update((byte)(exponent.length & 0x0ff));

            signature.update(exponent);

        }

    }

    /**

     * The RSA "ServerKeyExchange" handshake message producer.

     */

    private static final

            class RSAServerKeyExchangeProducer implements HandshakeProducer {

        // Prevent instantiation of this class.

        private RSAServerKeyExchangeProducer() {

            // blank

        }

        @Override

        public byte[] produce(ConnectionContext context,

                HandshakeMessage message) throws IOException {

            // The producing happens in server side only.

            ServerHandshakeContext shc = (ServerHandshakeContext)context;

            EphemeralRSAPossession rsaPossession = null;

            X509Possession x509Possession = null;

            for (SSLPossession possession : shc.handshakePossessions) {

                if (possession instanceof EphemeralRSAPossession) {

                    rsaPossession = (EphemeralRSAPossession)possession;

                    if (x509Possession != null) {

                        break;

                    }

                } else if (possession instanceof X509Possession) {

                    x509Possession = (X509Possession)possession;

                    if (rsaPossession != null) {

                        break;

                    }

                }

            }

            if (rsaPossession == null) {

                // The X.509 certificate itself should be used for RSA_EXPORT

                // key exchange.  The ServerKeyExchange handshake message is

                // not needed.

                return null;

            } else if (x509Possession == null) {

                // unlikely

                shc.conContext.fatal(Alert.ILLEGAL_PARAMETER,

                    "No RSA certificate negotiated for server key exchange");

            } else if (!"RSA".equals(

                    x509Possession.popPrivateKey.getAlgorithm())) {

                // unlikely

                shc.conContext.fatal(Alert.ILLEGAL_PARAMETER,

                        "No X.509 possession can be used for " +

                        "ephemeral RSA ServerKeyExchange");

            }

            RSAServerKeyExchangeMessage skem =

                    new RSAServerKeyExchangeMessage(

                            shc, x509Possession, rsaPossession);

            if (SSLLogger.isOn && SSLLogger.isOn("ssl,handshake")) {

                SSLLogger.fine(

                    "Produced RSA ServerKeyExchange handshake message", skem);

            }

            // Output the handshake message.

            skem.write(shc.handshakeOutput);

            shc.handshakeOutput.flush();

            // The handshake message has been delivered.

            return null;

        }

    }

    /**

     * The RSA "ServerKeyExchange" handshake message consumer.

     */

    private static final

            class RSAServerKeyExchangeConsumer implements SSLConsumer {

        // Prevent instantiation of this class.

        private RSAServerKeyExchangeConsumer() {

            // blank

        }

        @Override

        public void consume(ConnectionContext context,

                ByteBuffer message) throws IOException {

            // The consuming happens in client side only.

            ClientHandshakeContext chc = (ClientHandshakeContext)context;

            RSAServerKeyExchangeMessage skem =

                    new RSAServerKeyExchangeMessage(chc, message);

            if (SSLLogger.isOn && SSLLogger.isOn("ssl,handshake")) {

                SSLLogger.fine(

                    "Consuming RSA ServerKeyExchange handshake message", skem);

            }

            //

            // validate

            //

            // check constraints of RSA PublicKey

            RSAPublicKey publicKey;

            try {

                KeyFactory kf = JsseJce.getKeyFactory("RSA");

                RSAPublicKeySpec spec = new RSAPublicKeySpec(

                    new BigInteger(1, skem.modulus),

                    new BigInteger(1, skem.exponent));

                publicKey = (RSAPublicKey)kf.generatePublic(spec);

            } catch (GeneralSecurityException gse) {

                chc.conContext.fatal(Alert.INSUFFICIENT_SECURITY,

                        "Could not generate RSAPublicKey", gse);

                return;     // make the compiler happy

            }

            if (!chc.algorithmConstraints.permits(

                    EnumSet.of(CryptoPrimitive.KEY_AGREEMENT), publicKey)) {

                chc.conContext.fatal(Alert.INSUFFICIENT_SECURITY,

                        "RSA ServerKeyExchange does not comply to " +

                        "algorithm constraints");

            }

            //

            // update

            //

            chc.handshakeCredentials.add(new EphemeralRSACredentials(publicKey));

            //

            // produce

            //

            // Need no new handshake message producers here.

        }

    }

}