我在Debian 8上使用nginx 1.11.7和Openssl 1.1.0c ，并且有一个自我签名的ecc证书和384位密钥用于testing目的。
我想使用曲线X25519，secp384r1和secp256r1。
Nginx通常在nginx config中启用X25519和secp384r1：
ssl_ecdh_curve X25519:secp384r1; ，
但在使用secp256r1时拒绝重新启动/重新加载：
ssl_ecdh_curve secp256r1;
错误消息： SSL_CTX_set1_curves_list("secp256r1") failed (SSL:) 。
那么我怎样才能在上面提到的设置中使用secp256r1曲线？
原来P-256已经从列表中删除。
看到：
Why Is TLS 1.3 an advancement over TLS 1.2 or 1.1? TLS 1.3 removes support for known insecure ciphers such as RC4, DES, 3DES and export grade ciphers as well older hashing algorithms eg SHA-1 and MD5. These are welcome changes that should help to reduce the possibility of further vulnerabilities such as SWEET32 and FREAK being present within the code of TLS libraries eg OpenSSL. This reduces the attack surface (defined within the second paragraph of this blog post) of TLS 1.3 but the improvements don't stop there. Cipher suites such as NIST P-256 and AES-GCM are being removed as primitives with only x25519, ChaCha20 and Poly1305 remaining developed by Dan Bernstein (who uses the handle djb).
从这里： securityinaction.wordpress.com
该nginx版本的正确语法是：
ssl_ecdh_curve P-256;