nginx com certificado ECC de 384 bits e openssl mas curva secp256r1 não utilizável

Question

Estou usando nginx 1.11.7 com Openssl 1.1.0c no Debian 8 e tenho um certificado ecc auto-assinado com 384 Bit Key para fins de teste.

Eu gostaria de usar as curvas X25519, secp384r1 e secp256r1.

O Nginx inicia normalmente com o X25519 e o secp384r1 ativado na configuração do nginx:

ssl_ecdh_curve X25519:secp384r1; ,

mas se recusa a reiniciar / recarregar ao usar secp256r1:

ssl_ecdh_curve secp256r1;

A mensagem de erro: SSL_CTX_set1_curves_list("secp256r1") failed (SSL:) .

Então, como eu posso usar a curva secp256r1 com a configuração mencionada acima?

    

Answer 1

Acontece que o P-256 foi removido da lista.

Veja:

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 e.g. 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 e.g. 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).

A partir daqui: securityinaction .wordpress.com

    

Answer 2

A sintaxe correta para essa versão do nginx é:

ssl_ecdh_curve P-256;