How to get tls-unique in TLSv1.3

[daijc8501]

I can use BC jsse provider to get tls-unique value in TLS 1.2, code like:
SSLContext ctx = SSLContext.getInstance("TLS", BouncyCastleJsseProvider.PROVIDER_NAME);
ctx.init(...);
SSLSocketFactory sf = ctx.getSocketFactory();
SSLSocket so = (SSLSocket)sf.createSocket();
so.connect(new InetSocketAddress("www.baidu.com", 443));
...
BCSSLConnection con = ((BCSSLSocket)so).getConnection();
byte[] tlsUnique = con.getChannelBinding("tls-unique");

But when I changed host to tls13.1d.pw, the tlsUnique returned is null.
Is there something wrong in my code?
Thanks.

[peterdettman]

'tls-unique' is not available in TLS 1.3. See https://datatracker.ietf.org/doc/rfc9266/ for an overview.

Presumably switching to 'tls-exporter' for TLS 1.3 (or perhaps TLS 1.2 also) is the upgrade path, but it's not currently possible in BCJSSE to get that channel binding the way you describe above (see #1535).