EVP_PKEY_get_int_param is not getting degree from EC key

[Tomas Mraz]

On Tue, 2022-01-04 at 17:02 +0000, Blumenthal, Uri - 0553 - MITLL
wrote:
> >  > In other words, the man page says it's unsigned int, but in fact
> > it's
> >  > BIGNUM? Because the pointer I gave was to "unsigned int", like
> > in the
> >  > OP's code.
> > 
> >  The param is too big to fit into int. If you were using some
> >  ridiculously small EC curve the call would succeed. The parameter
> > types
> >  != C types and the manual page does not say "unsigned int" but
> >  "unsigned integer" for a reason.
> 
> Yes, that makes sense. 
> 
> But, considering that the man pages describe C API, wouldn't it be
> nice to mention (even though it may be obvious that a number of order
> 2^384 might not fit into 32 or even 64 bits) that the actual type is
> BIGNUM?

No, the type is not a BIGNUM. Please read "man OSSL_PARAM" it contains
the information on what types OSSL_PARAM support.

> Also, what should arguments to that C call EVP_PKEY_get_int_param()
> look like to succeed? Do I need to pass a pointer to BN there???

Please read "man EVP_PKEY_get_int_param".

-- 
Tomáš Mráz, OpenSSL