Problem: A handshake is attempted and fails when it cannot find a required algorithm. Examples might include:. If the SunJCE provider has been deregistered from the Provider mechanism and an alternative implementation from JCE is not available, then this exception will be thrown.
Solution: Ensure that the SunJCE is available by checking that the provider is registered with the Provider interface. Try to run the following code in the context of your SSL connection:. Problem: If you receive an Exception when trying to obtain application resources from your web server over TLS, and your web server is implemented as a virtual host that requires a valid Server Name Indication SNI extension such as Apache HTTP Server to distinguish the virtual host, then the web server might not be configured correctly.
The server may deny the client's request for a connection if the requested host name the server name indication does not match the expected server name, which should be specified in the virtual host's configuration. This triggers an TLS handshake unrecognized name alert, which results in an Exception being thrown.
Solution: If the cause of the problem is javax. This is similar to the mechanism that debugs security library issues. The generic Java dynamic debug tracing support is accessed with the java.
To view the options of the JSSE dynamic debug utility, use the following command-line option on the java command, where MyApp is an existing Java application:. The MyApp application will not run after the debug help information is printed, as the help code causes the application to exit.
If you specify the value help with either dynamic debug utility when running a program that does not use any classes that the utility was designed to debug, you will not get the debugging options. The following can be used with the ssl option to select what type of debug information to print:.
Messages generated from the handshake option can be widened with these options:. Messages generated from the record option can be widened with these options:. To enable JSSE-specific dynamic debug tracing, set the value of the javax. Security Property to either all or ssl. For the ssl option, to specify additional options, specify them after the ssl option. You do not have to have a separator between options, although a separator such as a colon : or a comma , helps readability.
It does not matter what separators you use, and the ordering of the option keywords is also not important. The following are examples of using the javax. To view the hexadecimal dumps of each handshake message, and to print trust manager tracing the commas are optional :. Understanding TLS connection problems can sometimes be difficult, especially when it is not clear what messages are actually being sent and received. JSSE has a built-in debug facility and is activated by the system property javax.
To know more about javax. This section gives a brief overview of the debug output of the basic TLS 1. Debug output information about all possible TLS handshake combinations and protocols is beyond the scope of this guide. Run ClassFileServer on localhost. The following command runs the ClassFileServer application on localhost , port Note that the command sets the value of the system property javax. Debug Output Format. Each line of the debug output contains the following information; each field is separated by a vertical bar :.
The values of the system properties jdk. The value of jdk. Initialize XKeyManager. The XKeyManager is initialized. It discovers that there is one keyEntry in the supplied KeyStore for a subject called "duke". If this application wants to authenticate itself, then the XKeyManager searches its list of keyEntries for an appropriate credential. Initialize a TrustManager. A TrustManager is initialized and it finds in the truststore several certificates from various Certificate Authorities CAs.
A server that presents valid credentials certificates that chain back to a trusted certificate in the truststore will itself be trusted. Perform Additional Initialization. The debug output also notifies you of disabled, unsupported, or unavailable extensions and signature algorithms:. Send ClientHello Message. Client version: For TLS 1. Cipher Suites: The list of cipher suites that the client requests; depending on the enabled cipher suites, there may be a broad mix of cipher suite names, some of which are only for TLSv1.
Note that this extension is deprecated for TLS 1. The extension is included in TLS 1. In particular, if the client requests TLS 1. This example contains key exchange information for the elliptical curve secpr1. Show Actual Data Sent and Read. The debug output shows the actual data sent to the raw output object in this case, an OutputStream :.
Then, the debug output shows the raw data read from the input device InputStream before any processing has been performed:. Whenever the client sends or reads a message, the debug output shows the raw data sent or read and how any messages and their extensions have been processed.
The following sections omit these parts of the debug output. Read ServerHello Message. At this point, TLS 1. In this case, a TLSv1. Server version: For TLS 1. Note that for TLS 1. Read EncryptedExtensions Message. At this point in the handshake, enough cryptographic information has been exchanged, and the remainder of the handshake will be performed encrypted. The EncryptedExtensions message contains responses to ClientHello extensions that are not required to determine the cryptographic parameters, other than those that are specific to individual certificates; in this example, it returns the list of named groups that the client supports for key exchange.
The server sends the CertificateRequest message if certificate-based client authentication is desired. This message contains the desired parameters for that certificate.
It specifies the following:. Extensions: The following two extensions indicate which signature algorithms may be used in digital signatures:. The Certificate message contains the authentication certificate and any other supporting certificates in the certificate chain. There are many different ways of establishing trust, so if the default XTrustManager is not doing the types of trust management you need, you can supply your own XTrustManager to SSLContext.
The certificate sent by the server is verified by the CertificateVerify message. The message is used to provide explicit proof that the server has the private key corresponding to its certificate. This message specifies the following:. Signature: The signature over the entire handshake using the private key corresponding to the public key in the Certificate message.
The server sends a Finished message. Send Certificate Message. The client sends a Certificate message because the server requested client authentication through a CertificateRequest message. The client needs to send credentials back to the sever, so its XKeyManager is consulted. The client looks for a match between the list of accepted issuers and the certificates that are in the KeyStore.
In this case, there is a match: the client has the credentials for "duke". It's now up to the server's XTrustManager to decide whether to accept these credentials. Send CertificateVerify Message. As with the CertificateVerify message sent by the server, the certificate sent by the client is verified by the CertificateVerify message. The message is used to provide explicit proof that the client has the private key corresponding to its certificate.
Send Finished Message. The client and server have verified the Finished messages that they have received from their peers. Both sides may now send and receive application data over the connection. The server and client are ready to exchange application data. Read NewSessionTicket Message. Close the Connection. Enhancements to JSSE may introduce compatibility problems and other known issues, which are described in this section. Although TLS 1. For applications that depend on the duplex-close policy, there may be compatibility issues when upgrading to TLS 1.
In practice, however, an application may use unsupported signature algorithms. The supported cipher suites for TLS 1. If an application hardcodes cipher suites that are no longer supported, it may not be able to use TLS 1.
The TLS 1. The compatibility impact should be minimal, but it could be a risk if an application depends on the handshake details of the TLS protocols. Converting an Unsecure Socket to a Secure Socket. Example shows sample code that can be used to set up communication between a client and a server using unsecure sockets. The following examples demonstrates server-side and client-side code for setting up an unsecure socket connection.
In a Java program that acts as a server and communicates with a client using sockets, the socket communication is set up with code similar to the following:. The following examples demonstrate server-side and client-side code for setting up a secure socket connection.
In a Java program that acts as a server and communicates with a client using secure sockets, the socket communication is set up with code similar to the following. Differences between this program and the one for communication using unsecure sockets are highlighted in bold. The client code to set up communication with a server using secure sockets is similar to the following, where differences with the unsecure version are highlighted in bold:. When you use the sample code, be aware that the sample programs are designed to illustrate how to use JSSE.
They are not designed to be robust applications. Setting up secure communications involves complex algorithms. The sample programs provide no feedback during the setup process. When you run the programs, be patient: you may not see any output for a while.
If you run the programs with the javax. Where to Find the Sample Code. That page also provides a link to a ZIP file that you can download to obtain all the sample code files. Sample Certificates and Keys. The JSSE samples use the following certificate keystore files to authenticate the clients and servers:. In the client program directories, the testkeys files contains the certificate entry for the Java mascot Duke. In the server program directories. The sample code expects the testkeys file to be in the current working directory.
These are very simple certificates and are not appropriate for a production environment, but they should be sufficient for running the samples here. The password for these keystores is: passphrase. This truststore file is very similar to the stock JDK cacerts file, in that it contains trust certificates from several vendors. It also contains the trusted certificates from Duke and localhost. The password for this keystore is the same as the JDK cacert 's initial password: changeit.
Please see your provider's documentation for how to configure the location of your trusted certificate file. Users of the JDK can specify the location of the truststore by using one of the following methods:.
If you choose 2 or 3 , be sure to replace this file with a production cacerts file before deployment. The utility keytool can be used to generate alternate certificates and keystore files. Ensure that you verify your cacerts file. Since you trust the CAs in the cacerts file as entities for signing and issuing certificates to other entities, you must manage the cacerts file carefully. The cacerts file should contain only certificates of the entities and CAs you trust.
It is your responsibility to verify the trusted root CA certificates bundled in the cacerts file and make your own trust decisions. To remove an untrusted CA certificate from the cacerts file, use the -delete command of the keytool utility with the -cacerts option.
Contact your system administrator if you do not have permission to edit this file. Alternatively, you can use your own truststore and keystore files. When running the sample client programs, you can communicate with an existing server, such as a web server, or you can communicate with the sample server program, ClassFileServer. You can run the sample client and the sample server programs on different machines connected to the same network, or you can run them both on one machine but from different terminal windows.
If an authentication error occurs during communication between the client and the server whether using a web server or ClassFileServer , it is most likely because the necessary keys are not in the truststore trust key database. See Terms and Definitions. For example, the ClassFileServer uses a keystore called testkeys containing the private key for localhost as needed during the SSL handshake.
If the client cannot find a certificate for the corresponding public key of localhost in the truststore it consults, then an authentication error will occur. Be sure to use the samplecacerts truststore which contains the public key and certificate of the localhost , as described in the next section. Configuration Requirements. When running the sample programs that create a secure socket connection between a client and a server, you will need to make the appropriate certificates file truststore available.
For both the client and the server programs, you should use the certificates file samplecacerts from the samples directory. Using this certificates file will allow the client to authenticate the server. The file contains all the common Certificate Authority CA certificates shipped with the JDK in the cacerts file , plus a certificate for localhost needed by the client to authenticate localhost when communicating with the sample server ClassFileServer.
The ClassFileServer uses a keystore containing the private key for localhost that corresponds to the public key in samplecacerts.
The password for the samplecacerts truststore is changeit. You can substitute your own certificates in the samples by using the keytool utility. If you use a browser, such as Mozilla Firefox or Microsoft Internet Explorer, to access the sample SSL server provided in the ClassFileServer example, then a dialog box may pop up with the message that it does not recognize the certificate. This is normal because the certificate used with the sample programs is self-signed and is for testing only.
You can accept the certificate for the current session. After testing the SSL server, you should exit the browser, which deletes the test certificate from the browser's namespace. For client authentication, a separate duke certificate is available in the appropriate directories. The public key and certificate is also stored in the samplecacerts file.
You must not be behind a firewall to run this program as provided. If you run it from behind a firewall, you will get an UnknownHostException because JSSE cannot find a path through your firewall to www. To create an equivalent client that can run from behind a firewall, set up proxy tunneling as illustrated in the sample program SSLSocketClientWithTunneling.
To run this program, you must set the following Java system properties to the appropriate values:. This program also assumes that the client is not outside a firewall. To run this program, you must specify three parameters: host name, port number, and requested file path. To mirror the previous examples, you can run this program without client authentication by setting the host to www. You can use the sample program ClassFileServer as this server.
This is described in the following sections. Running ClassFileServer. To execute them, run ClassFileServer. The TLS and true parameters are optional. If you omit them, indicating that an ordinary not TLS file server should be used, without authentication, then nothing happens.
This is because one side the client is trying to negotiate with TLS, while the other the server is not, so they cannot communicate. You can run both sample programs on different machines connected to the same network, or you can run them both on one machine but from different terminal windows or command prompt windows. To set up both the client and the server, do the following:. See Running ClassFileServer.
Forward slashes are required in the file path because it is used as part of a GET statement, which requires forward slashes regardless of what type of operating system you are running.
The statement is formed as follows:. System Property to the package name. URL class documentation for details. Both of these sample programs URLReader. Running URLReader. The URLReader. To use a different implementation, set the system property java. If you are running the sample code behind a firewall, then you must set the https.
For example, to use the proxy host "webproxy" on port , you can use the following options for the java command:. Alternatively, you can set the system properties within the source code with the java. System method setProperty. For example, instead of using the command-line options, you can include the following lines in your program:.
You need a protocolhandlerpkgs argument only if you want to use an HTTPS protocol handler implementation other than the default one provided by Oracle. If you are running the sample code behind a firewall, then you must include arguments for the proxy host and the proxy port. Additionally, you can include a list of cipher suites to enable. The sample code is basically a "Hello World" example modified to install and use a custom RMI socket factory.
Some introductory sample code is provided here that helps illustrate its use. A single loop serially performs all of the engine operations and demonstrates how a secure connection is established handshaking , how application data is transferred, and how the engine is closed.
This example does not examine all of the states. One of the most common problems people have in using JSSE is when the JSSE receives a certificate that is unknown to the mechanism that makes trust decisions. If an unknown certificate is received, the trust mechanism will throw an exception saying that the certificate is untrusted. Make sure that the correct trust store is being used, and that the JSSE is installed and configured correctly.
If you are using the "localhost" or "duke" credentials, be sure that you have correctly specified the location of the samplecacerts file, otherwise your application will not work. See Sample Certificates and Keys for more information.
The SSL debug mechanism can be used to investigate such trust problems. See the implementation documentation for more information about this subject.
First you make a keyEntry with public and private keys in the keystore, and then you make a corresponding trustedCertEntry public keys only in a truststore. For client authentication, you follow a similar process for the client's certificates.
Create a new keystore and self-signed certificate with corresponding public and private keys. Examine the keystore. Notice that the entry type is PrivatekeyEntry , which means that this entry has a private key associated with it. Examine the truststore. Note that the entry type is trustedCertEntry , which means that a private key is not available for this entry. It also means that this file is not suitable as a keystore of the KeyManager.
Now run your applications with the appropriate keystores. These examples illustrate how you can use the Server Name Indication SNI Extension for client-side and server-side applications, and how it can be applied to a virtual infrastructure.
The following is a list of use cases that require understanding of the SNI extension for developing a client application:. Oracle providers will set the host name in the SNI extension by default, but third-party providers may not support the default server name indication. To keep your application provider-independent, always set the host name explicitly. First switch the mode with the following method: sslSocket.
Then reset the server name indication parameters on the socket. The following is a list of use cases that require understanding of the SNI extension for developing a server application:. If you do not have any code dealing with the SNI extension, then the server ignores all server name indication types.
Case 2. Another way is to create an SNIMatcher subclass with a matches method that always returns false :. Case 3. The server wants to accept connections to any host names in the example. Preparing the ClientHello Parser. The SSLExplorer. The method must be called before handshaking occurs on any TLS connections.
This section describes the procedure for using a virtual server dispatcher based on SSLSocket. At this step, the application may create different SSLContext objects for different server name indications, or link a certain server name indication to a specified virtual machine or distributed system. For example, if the server name is www.
The local virtual hosting web service will use the specified SSLContext. If the server name is www. The handler may map this connection to the virtual machine. Create a ServerSocket and accept the new connection. Read and buffer bytes from the socket input stream, and then explore the buffered bytes. Look for the registered server name handler for this server name indication.
If the service of the host name is resident in a virtual machine or another distributed system, then the application must forward the connection to the destination. The application will need to read and write the raw internet data, rather then the SSL application from the socket stream. If the service of the host name is resident in the same process, and the host name service can use the SSLSocket directly, then the application will need to set the SSLSocket instance to the server:.
This section describes the procedure for using a virtual server dispatcher based on SSLEngine. If the service of the host name is resident in the same process, and the host name service can use the SSLEngine directly, then the application will simply feed the net data to the SSLEngine instance:. If there is no server name indication in a ClientHello message, then there is no way to select the proper service according to SNI.
For such cases, the application may need to specify a default service, so that the connection can be delegated to it if there is no server name indication. Failover SSLContext. In such cases, handle the exception thrown by SSLExplorer. The following example illustrates a failover SSLContext.
The following table describes which XML-related factory classes are disabled and which processing limits are set if JAXP security processing is enabled. The following sections describes the processing limits in this table in detail and how you can change them. Limiting Entity Expansion. Both properties accept java.
Integer values. The parser throws a fatal error once it has reached the entity expansion limit. Figure With JSSE, it is possible to develop client and server applications that use secure transport protocols, which include:. Starting with the release of J2SE 5. Security class. Implementation of the most common SSL and TLS Cipher suites to support authentication, key agreement, encryption, and integrity protection.
SocketFactory javax. SocketFactory : A factory class for creating Socket objects. The ServerSocketFactory is analogous to the SocketFactory class, but it is specific to creating server sockets.
SSLSocket javax. This class is available from J2SE 5. SSLSocketFactory javax. SSLSession javax. SSLSession : Represents the session attributes that describe the session negotiated between two communicating peers. The session context contains attributes such as the shared master secret key, network address of the remote peer, time, usage, and so forth.
SSLSessionContext javax. TrustManager javax. TrustManager : Represents an interface to determine whether the presented authentication credentials from the remote identity should be trusted or not trusted. TrustManagerFactory javax. HttpsURLConnection javax. HostnameVerifier javax. HostnameVerifier : Represents an interface class for hostname verification used for verifying the authenticity of the requests from the originating host.
In an SSL handshake, if the URL's hostname and the server's identification hostname mismatch, the verification mechanism uses this interface to verify the authenticity of the connection and its originating host. Let's take a look at a client and server communication scenario using the SSL and J2SE default keystore and truststore for storing certificates.
The SSL server uses the keystore that contains its private key and corresponding public key. The SSL client uses the server's certificate stored in the truststore to verify the authenticity of a communicating peer. For more information about setting up KeyStore and TrustStore and generating public and private keys using the KeyTool utility, refer to the section entitled "KeyTool" in Chapter 3. The programming steps involved in creating an SSL socket for a client-side application to communicate with a server using SSL is as follows:.
Overview of the Java Chat Application. In our examples, we'll first open the SSH connection, then execute one command, read. Client Server Program In Java Using Sockets,Using sockets for communication between the client and the server In this Java network programming tutorial, you will learn how to create a chat application in Java using Socket programming.
Dengan socket programming, komunikasi dapat terjalin antara bahasa pemrograman yang berbeda, antara tingkatan user yang berbeda, Java Security, 2nd Edition, will give you a clear understanding of the architecture of Java's security model and how to use that model in both programming and administration. The book is intended primarily for programmers who want to write secure Java applications. Java is secure due to the following reasons: Java programs run inside a virtual machine which is known as a sandbox.
This program also assumes that the client is not outside a firewall. In the java client program point the key store using javax. The IM application implements chat using Java's socket programming libraries.
In this article, we have basically seen the Simple Server and the Simple Client example where there is a connection between the server socket and in the.
SSL technology, created by Netscape, establishes a secure connection between a Web server and a browser, ensuring private and secure data transmission. The interface offered to applications is very simple and straightforward. Interprocess communication IPC is the backbone of distributed computing. Java Network Programming 9 0. More and more web apps are dynamic, immersive and do not require the end user to refresh. Processes are runtime representations of a program. In web technology, we have used front end and backend codes separately for creating web applications for the secure purpose.
The web application contains servers for receiving the client request and sent to the response for the clients' particular request. Java sockets have input streams and output streams built in, which makes programming rather pleasant. For example, Nadi et al. There is emerging support for low latency communication technologies like websockets. Secure Sockets Layer SSL is a standard technique for transmitting documents securely across a network. For this reason, Java provides the java.
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