Java tutorial
/* * Copyright 2010 dorkbox, llc * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package dorkbox.network.connection.registration.remote; import java.math.BigInteger; import java.net.InetSocketAddress; import java.security.SecureRandom; import java.util.concurrent.TimeUnit; import org.bouncycastle.crypto.AsymmetricCipherKeyPair; import org.bouncycastle.crypto.BasicAgreement; import org.bouncycastle.crypto.agreement.ECDHCBasicAgreement; import org.bouncycastle.crypto.digests.SHA384Digest; import org.bouncycastle.crypto.params.ECPublicKeyParameters; import org.bouncycastle.jce.ECNamedCurveTable; import org.bouncycastle.jce.spec.ECParameterSpec; import org.bouncycastle.util.Arrays; import com.esotericsoftware.kryo.KryoException; import com.esotericsoftware.kryo.io.Input; import com.esotericsoftware.kryo.io.Output; import dorkbox.network.connection.RegistrationWrapper; import dorkbox.network.connection.RegistrationWrapper.STATE; import dorkbox.network.connection.registration.MetaChannel; import dorkbox.network.connection.registration.Registration; import dorkbox.util.crypto.CryptoECC; import dorkbox.util.serialization.EccPublicKeySerializer; import io.netty.channel.Channel; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.EventLoopGroup; public class RegistrationRemoteHandlerServer extends RegistrationRemoteHandler { private static final long ECDH_TIMEOUT = TimeUnit.MINUTES.toNanos(10L); // 10 minutes in nanoseconds private static final ECParameterSpec eccSpec = ECNamedCurveTable.getParameterSpec(CryptoECC.curve25519); private final Object ecdhKeyLock = new Object(); private AsymmetricCipherKeyPair ecdhKeyPair; private volatile long ecdhTimeout = System.nanoTime(); RegistrationRemoteHandlerServer(final String name, final RegistrationWrapper registrationWrapper, final EventLoopGroup workerEventLoop) { super(name, registrationWrapper, workerEventLoop); } /** * @return the direction that traffic is going to this handler (" <== " or " ==> ") */ @Override protected String getConnectionDirection() { return " <== "; } /** * Rotates the ECDH key every 10 minutes, as this is a VERY expensive calculation to keep on doing for every connection. */ private AsymmetricCipherKeyPair getEchdKeyOnRotate(final SecureRandom secureRandom) { if (this.ecdhKeyPair == null || System.nanoTime() - this.ecdhTimeout > ECDH_TIMEOUT) { synchronized (this.ecdhKeyLock) { this.ecdhTimeout = System.nanoTime(); this.ecdhKeyPair = CryptoECC.generateKeyPair(eccSpec, secureRandom); } } return this.ecdhKeyPair; } /* * UDP has a VERY limited size, so we have to break up registration steps into the following * 1) session ID == 0 -> exchange session ID and public keys (session ID != 0 now) * 2) session ID != 0 -> establish ECDH shared secret as AES key/iv */ @SuppressWarnings("Duplicates") void readServer(final ChannelHandlerContext context, final Channel channel, final Registration registration, final String type, final MetaChannel metaChannel) { final InetSocketAddress remoteAddress = (InetSocketAddress) channel.remoteAddress(); // IN: session ID == 0 (start of new connection) // OUT: session ID + public key + ecc parameters (which are a nonce. the SERVER defines what these are) if (registration.sessionID == 0) { // whoa! Didn't send valid public key info! if (invalidPublicKey(registration, type)) { shutdown(channel, registration.sessionID); return; } // want to validate the public key used! This is similar to how SSH works, in that once we use a public key, we want to validate // against that ip-address::key pair, so we can better protect against MITM/spoof attacks. if (invalidRemoteAddress(metaChannel, registration, type, remoteAddress)) { // whoa! abort since something messed up! (log and recording if key changed happens inside of validate method) shutdown(channel, registration.sessionID); return; } // save off remote public key. This is ALWAYS the same, where the ECDH changes every time... metaChannel.publicKey = registration.publicKey; // tell the client to continue it's registration process. Registration outboundRegister = new Registration(metaChannel.sessionId); outboundRegister.publicKey = registrationWrapper.getPublicKey(); outboundRegister.eccParameters = CryptoECC .generateSharedParameters(registrationWrapper.getSecureRandom()); channel.writeAndFlush(outboundRegister); return; } // IN: remote ECDH shared payload // OUT: server ECDH shared payload if (metaChannel.aesKey == null) { /* * Diffie-Hellman-Merkle key exchange for the AES key * http://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange */ // the ECDH key will ROTATE every 10 minutes, since generating it for EVERY connection is expensive // and since we are combining ECDHE+ECC public/private keys for each connection, other // connections cannot break someone else's connection, since they are still protected by their own private keys. metaChannel.ecdhKey = getEchdKeyOnRotate(registrationWrapper.getSecureRandom()); byte[] ecdhPubKeyBytes = java.util.Arrays.copyOfRange(registration.payload, 0, registration.payload.length); ECPublicKeyParameters ecdhPubKey; try { ecdhPubKey = EccPublicKeySerializer.read(new Input(ecdhPubKeyBytes)); } catch (KryoException e) { logger.error("Invalid decode of ECDH public key. Aborting."); shutdown(channel, registration.sessionID); return; } BasicAgreement agreement = new ECDHCBasicAgreement(); agreement.init(metaChannel.ecdhKey.getPrivate()); BigInteger shared = agreement.calculateAgreement(ecdhPubKey); // now we setup our AES key based on our shared secret! (from ECDH) // the shared secret is different each time a connection is made byte[] keySeed = shared.toByteArray(); SHA384Digest sha384 = new SHA384Digest(); byte[] digest = new byte[sha384.getDigestSize()]; sha384.update(keySeed, 0, keySeed.length); sha384.doFinal(digest, 0); metaChannel.aesKey = Arrays.copyOfRange(digest, 0, 32); // 256bit keysize (32 bytes) metaChannel.aesIV = Arrays.copyOfRange(digest, 32, 44); // 96bit blocksize (12 bytes) required by AES-GCM if (invalidAES(metaChannel)) { // abort if something messed up! shutdown(channel, registration.sessionID); return; } Registration outboundRegister = new Registration(metaChannel.sessionId); Output output = new Output(1024); EccPublicKeySerializer.write(output, (ECPublicKeyParameters) metaChannel.ecdhKey.getPublic()); outboundRegister.payload = output.toBytes(); channel.writeAndFlush(outboundRegister); return; } // NOTE: if we have more registrations, we will "bounce back" that status so the client knows what to do. // IN: hasMore=true if we have more registrations to do, false otherwise // ALWAYS upgrade the connection at this point. // IN: upgraded=false if we haven't upgraded to encryption yet (this will always be the case right after encryption is setup) if (!registration.upgraded) { // upgrade the connection to an encrypted connection registration.upgrade = true; upgradeDecoders(channel, metaChannel); // bounce back to the client so it knows we received it channel.write(registration); // this pipeline encoder/decoder can now be upgraded, and the "connection" added upgradeEncoders(channel, metaChannel, remoteAddress); if (!registration.hasMore) { // we only get this when we are 100% done with the registration of all connection types. // setup the pipeline with the real connection upgradePipeline(metaChannel, remoteAddress); } channel.flush(); return; } // the client will send their class registration data. VERIFY IT IS CORRECT! STATE state = registrationWrapper.verifyClassRegistration(metaChannel, registration); if (state == STATE.ERROR) { // abort! There was an error shutdown(channel, registration.sessionID); return; } else if (state == STATE.WAIT) { return; } // else, continue. // // // we only get this when we are 100% done with the registration of all connection types. // the context is the LAST protocol to be registered // // // remove the ConnectionWrapper (that was used to upgrade the connection) and cleanup the pipeline cleanupPipeline(metaChannel, new Runnable() { @Override public void run() { // this method runs after the "onConnect()" runs and only after all of the channels have be correctly updated // this tells the client we are ready to connect (we just bounce back the original message over ALL protocols) if (metaChannel.tcpChannel != null) { logger.trace("Sending TCP upgraded command"); Registration reg = new Registration(registration.sessionID); reg.upgraded = true; metaChannel.tcpChannel.writeAndFlush(reg); } if (metaChannel.udpChannel != null) { logger.trace("Sending UDP upgraded command"); Registration reg = new Registration(registration.sessionID); reg.upgraded = true; metaChannel.udpChannel.writeAndFlush(reg); } } }); } }