Chapter 3. Red Hat build of OpenJDK features

The latest Red Hat build of OpenJDK 21 release might include new features. Additionally, the latest release might enhance, deprecate, or remove features that originated from earlier Red Hat build of OpenJDK 21 releases.

Red Hat build of OpenJDK enhancements

Red Hat build of OpenJDK 21 provides enhancements to features originally created in earlier releases of Red Hat build of OpenJDK.

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 21.0.5 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

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).

KEM.getInstance() method checks if a third-party security provider is signed

The JDK’s cryptographic framework authenticates third-party security provider implementations by determining the provider’s codebase and by verifying the provider’s signature.

In earlier releases, the JDK did not authenticate key encapsulation mechanism (KEM) implementations.

Red Hat build of OpenJDK 21.0.5 authenticates KEM implementations in a manner that is consistent with other JDK service types, such as Cipher and Mac providers.

See JDK-8322971 (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 21.0.5, 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).

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

Red Hat build of OpenJDK 21.0.5 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).

SSL.com root certificates added

In Red Hat build of OpenJDK 21.0.5, the cacerts truststore includes two SSL.com TLS root certificates:

See JDK-8341057 (JDK Bug System).

HTTP client enhancements

Red Hat build of OpenJDK 21.0.5 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 21.0.5 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 21.0.5 onward, the ClassLoadingMXBean.isVerbose() and MemoryMXBean.isVerbose() methods display the following behavior:

See JDK-8338139 (JDK Bug System).