tsaarni commented on code in PR #1919:
URL: https://github.com/apache/zookeeper/pull/1919#discussion_r1338936374
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zookeeper-server/src/main/java/org/apache/zookeeper/common/X509Util.java:
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@@ -81,7 +87,32 @@ public abstract class X509Util implements Closeable,
AutoCloseable {
}
}
- public static final String DEFAULT_PROTOCOL = "TLSv1.2";
+ public static final String DEFAULT_PROTOCOL = defaultTlsProtocol();
+
+ /**
+ * Return TLSv1.3 or TLSv1.2 depending on Java runtime version being used.
+ * TLSv1.3 was first introduced in JDK11 and back-ported to OpenJDK 8u272.
+ */
+ private static String defaultTlsProtocol() {
+ String defaultProtocol = "TLSv1.2";
+ List<String> supported = new ArrayList<>();
+ try {
+ supported =
Arrays.asList(SSLContext.getDefault().getSupportedSSLParameters().getProtocols());
+ if (supported.contains("TLSv1.3")) {
+ defaultProtocol = "TLSv1.3";
+ }
+ } catch (NoSuchAlgorithmException e) {
+ // Ignore.
+ }
+ LOG.info("Default TLS protocol is {}, supported TLS protocols are {}",
defaultProtocol, supported);
+ return defaultProtocol;
+ }
+
+ // ChaCha20 was introduced in OpenJDK 11.0.15 and it is not supported by
JDK8.
+ private static String[] getTLSv13Ciphers() {
+ return new String[]{"TLS_AES_256_GCM_SHA384",
"TLS_AES_128_GCM_SHA256", "TLS_CHACHA20_POLY1305_SHA256"};
+ }
Review Comment:
Since the cipher list is hardcoded, I needed to extend it with TLSv1.3
ciphers. My approach was to list all TLSv1.3 ciphers that JDK would normally
enable by default. So, I created the list by checking what
`SSLServerSocketFactory.getDefault().getDefaultCipherSuites()` returns on
recent JDK, and out from that list I picked the ones that are for TLSv1.3. This
also happens to match with list recommended here
https://wiki.mozilla.org/Security/Server_Side_TLS#Modern_compatibility.
There are more TLSv1.3 ciphers in JDK, but Java does not enable them by
default
https://docs.oracle.com/en/java/javase/17/docs/specs/security/standard-names.html#jsse-cipher-suite-names
(see rows where column "Introduced in" says TLSv1.3).
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