Question about migrating from d2i_ECPrivateKey() to d2i_PrivateKey(EVP_PKEY_EC, ...)

[Nico Williams]

I've some source code using deprecated EC_KEY APIs that does this:

    group = EC_GROUP_new_by_curve_name(groupnid);
    EC_GROUP_set_asn1_flag(group, OPENSSL_EC_NAMED_CURVE);

    key = EC_KEY_new();
    EC_KEY_set_group(key, group);

    pkey = &key;

    /* `p' has the private key of length `len' */
    result = d2i_ECPrivateKey(pkey, &p, len);

I need to update it to use EVP_PKEY APIs.  That should be easy enough, I
thought, but I'm lost on how to replace the EC_KEY_set_group() call.

I can't use d2i_PrivateKey() because that requires an existing
EVP_PKEY * that has the group already set.

So use d2i_PrivateKey_ex()?  But I don't see how it gets the group
either.  Is it via the propq parameter?  How?

If this is described in the docs, I've missed it.

Thanks,

Nico
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