crypto:generate_key/3 on explicit curves is broken

[RoadRunnr]

Describe the bug

The spec is -spec generate_key(Type, Params, PrivKeyIn) -> {PublicKey, PrivKeyOut} where Params is allow to be a ec_explicit_curve(). That type contains all parameters to define a curve. However, attempting to generate a key on a valid, explicit curve fails.

To Reproduce

Define a curve that uses the curve parameters of secp256k1, but uses a different generator,

Curve = {{prime_field,<<"ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿþÿÿü/">>},
 {<<0>>,<<7>>,none},
 <<4,198,4,127,148,65,237,125,109,48,69,64,110,149,192,124,
   216,92,119,142,75,140,239,60,167,171,172,9,185,92,112,
   158,229,26,225,104,254,166,61,195,57,163,197,132,25,70,
   108,234,238,247,246,50,101,50,102,208,225,35,100,49,169,
   80,207,229,42>>,
 <<255,255,255,255,255,255,255,255,255,255,255,255,255,255,
   255,254,186,174,220,230,175,72,160,59,191,210,94,140,
   208,54,65,65>>,
 <<1>>}.
crypto:generate_key(ecdh, Curve, 2).
** exception error: {error,{"ec.c",465},"Couldn't get EC group name size"}
     in function  crypto:generate_key/2
        called as crypto:generate_key({{{prime_field,<<"ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿþÿÿü/">>},
                                        {<<0>>,<<7>>,none},
                                        <<4,198,4,127,148,65,237,125,109,48,69,64,110,149,192,124,
                                          216,92,119,142,75,140,239,60,...>>,
                                        <<"ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿþº®Üæ¯H ;¿Ò^"...>>,
                                        <<1>>},
                                       undefined},
                                      <<2>>)

The problem is that code attempts to get a name for curve and then use that named curve to initialize the curve parameters. That obviously won't work for curves with non-standard parameters.
Since all curve parameters are given, the code should instead initialize the curve context from the given values.

Expected behavior

Generating points on explicit curves should work.

Affected versions

• OTP-28.0-rc2
• OTP-27.3

Additional context

I am relatively certain that it did work when I submitted the original version of the EC key support in 2014. A quick inspection suggests that the OpenSSL 3.0 API changes broken it.