sign

static VALUE
ossl_spki_sign(VALUE self, VALUE key, VALUE digest)
{
    NETSCAPE_SPKI *spki;
    EVP_PKEY *pkey;
    const EVP_MD *md;

    pkey = GetPrivPKeyPtr(key); /* NO NEED TO DUP */
    md = GetDigestPtr(digest);
    GetSPKI(self, spki);
    if (!NETSCAPE_SPKI_sign(spki, pkey, md)) {
        ossl_raise(eSPKIError, NULL);
    }

    return self;
}