When using Java 8 update 162 and older in Internet Explorer, the applet loads and works as expected. When removing Java 8 update 162 and install Java 8 update 171 or 172, the applet errors with ClassNotFoundException referencing the class listed in the code attribute of the applet tag. I don't see any reason for this in the 171 or 172 release notes or the 171 or 172 bug fixes. I'm using Windows 10 Pro version 1709 build 16299.371. The applet is signed with a certificate that is trusted and still valid. There aren't any exceptions in the Exception Site List and adding an exception for this site (it worked fine without one on Java 8u162) still displays the exception. Using Java 8 update 162 and older is still working on another PC.
When clearing the Application cache in the Java configuration, the applet's JAR file doesn't appear again in the cache.
Are you aware of any changes in Java 8u171 or 172 that affect applets? Do you have any suggestions to resolve this?
Update 1: I'm aware that applets are deprecated in Java 9 and that applets don't work in Firefox and Chrome, but this is in Internet Explorer.
Update 2: I'm also aware that the 3DES Cipher Suites have been disabled in the update to 171 and 172, but the current digest algorithm is SHA-256 and the signature algorithm is SHA256withRSA with a 2048-bit key, which matches the signing certificate's signature algorithm and key. I've even tried signing the applet using Java 8 Update 172 without altering java.security to remove 3DES_EDE_CBC and using that version the ClassNotFoundException still persists as expected.
Update 3: When using Fiddler 4 or Charles as a proxy for Internet Explorer and capturing traffic between the server and the browser, the applet loads and works as expected. Both the Java SE Runtime Environment 8 Update 172 and Java Plug-in 11.172.2 Add-ons are set to Allow on all sites. When I clear the applet from the Resources cache using the Java Cache Viewer in the Java Control Panel, the applet doesn't download in the cache again without the proxy, but if I use a proxy again then it does download into the cache. My guess is that the proxy traffic is being treated as local and so has different permissions. Any other ideas or what permissions it could be?
Update 4: Enabling the debugging options in the Java Control Panel causes the full stack trace to show, where CODE_ATTRIBUTE_VALUE is the value I set on the code attribute of the applet tag. The applet's JAR file doesn't seem to be downloading even though I list it in the archive attribute.
java.lang.ClassNotFoundException: CODE_ATTRIBUTE_VALUE
at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source)
at sun.plugin2.applet.Plugin2Manager.initAppletAdapter(Unknown Source)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
The Java Console now also shows more details about the connection and I see the following which is the cause:
javax.net.ssl.SSLHandshakeException: Remote host closed connection during handshake
at sun.security.ssl.SSLSocketImpl.readRecord(Unknown Source)
at sun.security.ssl.SSLSocketImpl.performInitialHandshake(Unknown Source)
at sun.security.ssl.SSLSocketImpl.startHandshake(Unknown Source)
at sun.security.ssl.SSLSocketImpl.startHandshake(Unknown Source)
at sun.net.www.protocol.https.HttpsClient.afterConnect(Unknown Source)
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(Unknown Source)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.connect(Unknown Source)
at sun.plugin.PluginURLJarFileCallBack.connect(Unknown Source)
at sun.plugin.PluginURLJarFileCallBack.retrieve(Unknown Source)
at sun.net.www.protocol.jar.URLJarFile.retrieve(Unknown Source)
at sun.net.www.protocol.jar.URLJarFile.getJarFile(Unknown Source)
at sun.net.www.protocol.jar.JarFileFactory.get(Unknown Source)
at sun.net.www.protocol.jar.JarURLConnection.connect(Unknown Source)
at sun.plugin.net.protocol.jar.CachedJarURLConnection.connect(Unknown Source)
at sun.plugin.net.protocol.jar.CachedJarURLConnection.getJarFileInternal(Unknown Source)
at sun.plugin.net.protocol.jar.CachedJarURLConnection.getJarFile(Unknown Source)
at com.sun.deploy.security.DeployURLClassPath$JarLoader.getJarFile(Unknown Source)
at com.sun.deploy.security.DeployURLClassPath$JarLoader.access$900(Unknown Source)
at com.sun.deploy.security.DeployURLClassPath$JarLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.deploy.security.DeployURLClassPath$JarLoader.ensureOpen(Unknown Source)
at com.sun.deploy.security.DeployURLClassPath$JarLoader.<init>(Unknown Source)
at com.sun.deploy.security.DeployURLClassPath$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.deploy.security.DeployURLClassPath.getLoader(Unknown Source)
at com.sun.deploy.security.DeployURLClassPath.getLoader(Unknown Source)
at com.sun.deploy.security.DeployURLClassPath.getResource(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader$2.run(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader$2.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.plugin2.applet.Plugin2ClassLoader.findClassHelper(Unknown Source)
at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source)
at sun.plugin2.applet.Plugin2Manager.initAppletAdapter(Unknown Source)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.io.EOFException: SSL peer shut down incorrectly
at sun.security.ssl.InputRecord.read(Unknown Source)
... 40 more
Currently the applet is hosted on Windows Server 2003 using IIS. Moving it to Windows Server 2008 also using IIS causes that problem to go away. Mr. Laitinen was right the TLS connection was using 3DES_EDE_CBC.
JAVA_HOME\lib\security\java.security
Update 171 adds 3DES_EDE_CBC to the list of disabled algorithms (jdk.tls.disabledAlgorithms). Remove it and your applet will work again.