curl-w32/docs/cmdline-opts/curves.md

c	SPDX-License-Identifier	Long	Arg	Help	Protocols	Added	Category	Multi	See-also	Example
Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.	curl	curves	<algorithm list>	(EC) TLS key exchange algorithm(s) to request	TLS	7.73.0	tls	single	ciphers	--curves X25519 $URL

--curves

Tells curl to request specific curves to use during SSL session establishment according to RFC 8422, 5.1. Multiple algorithms can be provided by separating them with : (e.g. X25519:P-521). The parameter is available identically in the OpenSSL s_client and s_server utilities.

--curves allows a OpenSSL powered curl to make SSL-connections with exactly the (EC) curve requested by the client, avoiding nontransparent client/server negotiations.

If this option is set, the default curves list built into OpenSSL are ignored.