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Question about CURLOPT_TLS13_CIPHERS

From: Bernhard Jaeger <>
Date: Thu, 2 Aug 2018 09:47:26 +0200
Until libcurl 7.60 the CURLOPT_TLS13_CIPHERS option was necessary to use TLS 1.3 with libcurl.
However the option was not documented so I assumed it was a boolean to toggle tls 13 on and I set the option like this:
curl_easy_setopt(curl, CURLOPT_TLS13_CIPHERS, 1L);
Which worked I could successfully establish a TLS 1.3 connection (with better Appconnect times than TLS 1.2)
Now with 7.61 the documentation for the option got added an I realized 1L makes no sense as an argument as the library expects a zero terminated string or NULL.
I am curious why it worked anyways. Can somebody familiar with the libcurl code tell me what passing 1L as an argument does?
My second question is about the NULL argument:
Documentation: " NULL, use internal default "
What is the internal default?
The full list of TLS 1.3 ciphers? (TLS13-AES-256-GCM-SHA384 TLS13-CHACHA20-POLY1305-SHA256 TLS13-AES-128-GCM-SHA256 TLS13-AES-128-CCM-8-SHA256 TLS13-AES-128-CCM-SHA256)
-- Bernhard Jaeger

Received on 2018-08-02