Chapter 3. Red Hat build of OpenJDK features

The latest Red Hat build of OpenJDK 17 release might include new features. Additionally, the latest release might enhance, deprecate, or remove features that originated from earlier Red Hat build of OpenJDK 17 releases.

Red Hat build of OpenJDK enhancements

Red Hat build of OpenJDK 17 provides enhancements to features originally created in earlier releases of Red Hat build of OpenJDK.

Fix for jpackage tool producing an inaccurate list of required packages on Debian Linux

In earlier releases, on Debian Linux platforms, the jpackage tool could produce an inaccurate list of required packages from shared libraries with symbolic links in their paths.

Red Hat build of OpenJDK 17.0.13 resolves this issue to eliminate installation failures that could result from missing shared libraries.

See JDK-8295111 (JDK Bug System).

TLS_ECDH_* cipher suites are disabled by default

The TLS Elliptic-curve Diffie-Hellman (TLS_ECDH) cipher suites do not preserve forward secrecy and they are rarely used. Red Hat build of OpenJDK 17.0.13 disables the TLS_ECDH cipher suites by adding the ECDH option to the jdk.tls.disabledAlgorithms security property in the java.security configuration file. If you attempt to use the TLS_ECDH cipher suites, Red Hat build of OpenJDK now throws an SSLHandshakeException error.

If you want to continue using the TLS_ECDH cipher suites, you can remove ECDH from the jdk.tls.disabledAlgorithms security property either by modifying the java.security configuration file or by using the java.security.properties system property.

See JDK-8279164 (JDK Bug System).

Distrust of TLS server certificates issued after 11 November 2024 and anchored by Entrust root CAs

In accordance with similar plans that Google and Mozilla recently announced, Red Hat build of OpenJDK 17.0.13 distrusts TLS certificates that are issued after 11 November 2024 and anchored by Entrust root certificate authorities (CAs). This change in behavior includes any certificates that are branded as AffirmTrust, which are managed by Entrust.

Red Hat build of OpenJDK will continue to trust certificates that are issued on or before 11 November 2024 until these certificates expire.

If a server’s certificate chain is anchored by an affected certificate, any attempts to negotiate a TLS session now fail with an exception to indicate that the trust anchor is not trusted. For example:

TLS server certificate issued after 2024-11-11 and anchored by a distrusted legacy Entrust root CA: CN=Entrust.net CertificationAuthority (2048), OU=(c) 1999 Entrust.net Limited,OU=www.entrust.net/CPS_2048 incorp. by ref. (limits liab.),O=Entrust.net

TLS server certificate issued after 2024-11-11 and anchored by a distrusted legacy Entrust root CA: CN=Entrust.net CertificationAuthority (2048), OU=(c) 1999 Entrust.net Limited,OU=www.entrust.net/CPS_2048 incorp. by ref. (limits liab.),O=Entrust.net

You can check whether this change affects a certificate in a JDK keystore by using the following keytool command:

keytool -v -list -alias <your_server_alias> -keystore <your_keystore_filename>

If this change affects any certificate in the chain, update this certificate or contact the organization that is responsible for managing the certificate.

If you want to continue using TLS server certificates that are anchored by Entrust root certificates, you can remove ENTRUST_TLS from the jdk.security.caDistrustPolicies security property either by modifying the java.security configuration file or by using the java.security.properties system property.

These restrictions apply to the following Entrust root certificates that Red Hat build of OpenJDK includes:

See JDK-8337664 (JDK Bug System) and JDK-8341059 (JDK Bug System).

Reduced verbose locale output in -XshowSettings launcher option

In earlier releases, the -XshowSettings launcher option printed a long list of available locales, which obscured other settings.

In Red Hat build of OpenJDK 17.0.13, the -XshowSettings launcher option no longer prints the list of available locales by default. If you want to view all settings that relate to the available locales, you can use the -XshowSettings:locale option.

See JDK-8310201 (JDK Bug System).

SSL.com root certificates added

In Red Hat build of OpenJDK 17.0.13, the cacerts truststore includes two SSL.com TLS root certificates:

See JDK-8341057 (JDK Bug System).

Additional timestamp and thread options for java.security.debug system property

Red Hat build of OpenJDK 17.0.13 adds the following options to the java.security.debug property, which can be applied to any specified component:

For example, -Djava.security.debug=all+timestamp+thread enables debug information for all components with both timestamps and thread information. Alternatively, -Djava.security.debug=properties+timestamp enables debug information only for security properties and includes a timestamp. You can use -Djava.security.debug=help to display a complete list of supported components and options.

See JDK-8051959 (JDK Bug System).

Relaxation of Java Abstract Window Toolkit (AWT) Robot specification

Red Hat build of OpenJDK 17.0.13 is based on the latest maintenance release of the Java 17 specification. This release relaxes the specification of the following three methods in the java.awt.Robot class:

This relaxation of the specification allows these methods to fail when the desktop environment does not permit moving the mouse pointer or capturing screen content.

See JDK-8307779 (JDK Bug System).

Changes to com.sun.jndi.ldap.object.trustSerialData system property

The JDK implementation of the LDAP provider no longer supports the deserialization of Java objects by default.

In Red Hat build of OpenJDK 17.0.13, the com.sun.jndi.ldap.object.trustSerialData system property is set to false by default. This release also increases the scope of the com.sun.jndi.ldap.object.trustSerialData property to cover the reconstruction of RMI remote objects from the javaRemoteLocation LDAP attribute.

These changes mean that transparent deserialization of Java objects now requires an explicit opt-in. From Red Hat build of OpenJDK 17.0.13 onward, if you want to allow applications to reconstruct Java objects and RMI stubs from LDAP attributes, you must explicitly set the com.sun.jndi.ldap.object.trustSerialData property to true.

See JDK-8290367 (JDK Bug System) and JDK-8332643 (JDK Bug System).

HTTP client enhancements

Red Hat build of OpenJDK 17.0.13 limits the maximum header field size that the HTTP client accepts within the JDK for all supported versions of the HTTP protocol. The header field size is computed as the sum of the size of the uncompressed header name, the size of the uncompressed header value, and an overhead of 32 bytes for each field section line. If a peer sends a field section that exceeds this limit, a java.net.ProtocolException is raised.

Red Hat build of OpenJDK 17.0.13 introduces a jdk.http.maxHeaderSize system property that you can use to change the maximum header field size (in bytes). Alternatively, you can disable the maximum header field size by setting the jdk.http.maxHeaderSize property to zero or a negative value. The jdk.http.maxHeaderSize property is set to 393,216 bytes (that is, 384KB) by default.

See JDK-8328286 (JDK Bug System).

ClassLoadingMXBean and MemoryMXBean APIs have isVerbose() methods consistent with their setVerbose() methods

The setVerbose(boolean enabled) method for the ClassLoadingMXBean API displays the following behavior:

In earlier releases, the isVerbose() method for the ClassLoadingMXBean API checked if class+load logging was enabled at the Info level on any type of log output, not just stdout. In this situation, if you enabled logging to a file by using the java -Xlog option, the isVerbose() method returned true even if setVerbose(false) was called, which resulted in counterintuitive behavior. The isVerbose() method for the MemoryMXBean API also displayed similar counterintuitive behavior.

From Red Hat build of OpenJDK 17.0.13 onward, the ClassLoadingMXBean.isVerbose() and MemoryMXBean.isVerbose() methods display the following behavior:

See JDK-8338139 (JDK Bug System).

Key encapsulation mechanism API

Red Hat build of OpenJDK 17.0.13 introduces a javax.crypto API for key encapsulation mechanisms (KEMs). KEM is an encryption technique for securing symmetric keys by using public key cryptography. The javax.crypto API facilitates the use of public key cryptography and helps to improve security when handling secrets and messages.

See JDK-8297878 (JDK Bug System).

Changes to naming convention for Windows build artifacts

This release introduces naming changes for some files that are distributed as part of Red Hat build of OpenJDK 17 for Windows Server platforms.

These file naming changes affect both the .zip archive and .msi installers that Red Hat provides for the JDK, JRE and debuginfo packages for Red Hat build of OpenJDK 17.

The aim of this change is to adopt a common naming convention that is consistent across the different versions of OpenJDK that Red Hat currently supports. This means that Red Hat build of OpenJDK 17 is now aligned with the naming convention that Red Hat has already adopted for Red Hat build of OpenJDK 21.

These changes do not affect the files for Linux portable builds.

The following list provides an example of how these naming changes affect files in Red Hat build of OpenJDK 17: