带有 TLS 1.3 的“nghttp2::asio_http2::client” - SSL_CTX_set_cipher_list 不在密码套件中添加密码套件

Question

I use nghttp2 asio_http2_client with TLS 1.3 protocol, but when i try to add additional suites in cipher suites list via SSL_CTX_get_ciphers function, i don't see anything changes in my Client hello message. Ie cipher suites list stay without changes.

My code example:

#include <nghttp2/asio_http2_client.h>

#include <iostream>

using boost::asio::ip::tcp;

using namespace nghttp2::asio_http2;
using namespace nghttp2::asio_http2::client;

int main(int argc, char* argv[])
{
    boost::system::error_code ec;
    boost::asio::io_service io_service;

    boost::asio::ssl::context tls(boost::asio::ssl::context::tlsv13_client);
    tls.set_verify_mode(boost::asio::ssl::verify_peer);

    // https://testssl.sh/openssl-iana.mapping.html
    auto rc = SSL_CTX_set_cipher_list(
        tls.native_handle(),
        R"(TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256:TLS_AES_256_GCM_SHA384:ECDHE-ECDSA-CHACHA20-POLY1305-OLD:ECDHE-RSA-CHACHA20-POLY1305-OLD:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-RSA-AES256-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA:AES256-SHA)");
    if (rc != 1) {
        std::cout << "no cipher list found " << rc << std::endl;
    }

    auto ciph = SSL_CTX_get_ciphers(tls.native_handle());
    printf("after SSL_CTX_set_ciphersuites()\n");
    for (size_t i = 0; i < sk_SSL_CIPHER_num(ciph); i++)
        printf("%s%s", i != 0 ? ":" : "", SSL_CIPHER_get_name(sk_SSL_CIPHER_value(ciph, i)));


    //    return 1;
    configure_tls_context(ec, tls);

    // connect to
    session sess(io_service, tls, "www.google.com", "443");

    sess.on_connect([&sess](tcp::resolver::iterator endpoint_it) {
        boost::system::error_code ec;

        std::cerr << "Connected!" << std::endl;
    });


    sess.on_error([](const boost::system::error_code& ec) {
        std::cerr << "error: " << ec.message() << std::endl;
    });

    io_service.run();
}

In wireshark i see following output(4 cipher suites,but there are many more cipher suites in the SSL_CTX_set_cipher_list arguments):

I did an experiment with SSL_CTX_set_cipher_list and commented out the next lines:

    auto rc = SSL_CTX_set_cipher_list(
        tls.native_handle(),
        R"(TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256:TLS_AES_256_GCM_SHA384:ECDHE-ECDSA-CHACHA20-POLY1305-OLD:ECDHE-RSA-CHACHA20-POLY1305-OLD:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-RSA-AES256-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA:AES256-SHA)");
    if (rc != 1) {
        std::cout << "no cipher list found " << rc << std::endl;
    }

    auto ciph = SSL_CTX_get_ciphers(tls.native_handle());
    printf("after SSL_CTX_set_ciphersuites()\n");
    for (size_t i = 0; i < sk_SSL_CIPHER_num(ciph); i++)
        printf("%s%s", i != 0 ? ":" : "", SSL_CIPHER_get_name(sk_SSL_CIPHER_value(ciph, i)));

But cipher suite list remained the same. Whats wrong?

Answer 1

If you go to the documentation for SSL_CTX_get_ciphers it states:

SSL_CTX_set_cipher_list() sets the list of available ciphers (TLSv1.2 and below)

and

This function does not impact TLSv1.3 ciphersuites. Use SSL_CTX_set_ciphersuites() to configure those.

So you need to go read the SSL_CTX_set_cipher_list API as the v1.3 cipher list is a lot different and much smaller than up to v1.2 cipher list.