OpenSSL::PKey::DSA.new

static VALUE
ossl_dsa_initialize(int argc, VALUE *argv, VALUE self)
{
    EVP_PKEY *pkey;
    DSA *dsa;
    BIO *in;
    VALUE arg, pass;

    GetPKey(self, pkey);
    if(rb_scan_args(argc, argv, "02", &arg, &pass) == 0) {
        dsa = DSA_new();
    }
    else if (RB_INTEGER_TYPE_P(arg)) {
        if (!(dsa = dsa_generate(NUM2INT(arg)))) {
            ossl_raise(eDSAError, NULL);
        }
    }
    else {
        pass = ossl_pem_passwd_value(pass);
        arg = ossl_to_der_if_possible(arg);
        in = ossl_obj2bio(&arg);
        dsa = PEM_read_bio_DSAPrivateKey(in, NULL, ossl_pem_passwd_cb, (void *)pass);
        if (!dsa) {
            OSSL_BIO_reset(in);
            dsa = PEM_read_bio_DSA_PUBKEY(in, NULL, NULL, NULL);
        }
        if (!dsa) {
            OSSL_BIO_reset(in);
            dsa = d2i_DSAPrivateKey_bio(in, NULL);
        }
        if (!dsa) {
            OSSL_BIO_reset(in);
            dsa = d2i_DSA_PUBKEY_bio(in, NULL);
        }
        if (!dsa) {
            OSSL_BIO_reset(in);
#define PEM_read_bio_DSAPublicKey(bp,x,cb,u) (DSA *)PEM_ASN1_read_bio( \
        (d2i_of_void *)d2i_DSAPublicKey, PEM_STRING_DSA_PUBLIC, (bp), (void **)(x), (cb), (u))
            dsa = PEM_read_bio_DSAPublicKey(in, NULL, NULL, NULL);
#undef PEM_read_bio_DSAPublicKey
        }
        BIO_free(in);
        if (!dsa) {
            ossl_clear_error();
            ossl_raise(eDSAError, "Neither PUB key nor PRIV key");
        }
    }
    if (!EVP_PKEY_assign_DSA(pkey, dsa)) {
        DSA_free(dsa);
        ossl_raise(eDSAError, NULL);
    }

    return self;
}