OpenSSL::KDF.pbkdf2_hmac

static VALUE
kdf_pbkdf2_hmac(int argc, VALUE *argv, VALUE self)
{
    VALUE pass, salt, opts, kwargs[4], str, md_holder;
    static ID kwargs_ids[4];
    int iters, len;
    const EVP_MD *md;

    if (!kwargs_ids[0]) {
        kwargs_ids[0] = rb_intern_const("salt");
        kwargs_ids[1] = rb_intern_const("iterations");
        kwargs_ids[2] = rb_intern_const("length");
        kwargs_ids[3] = rb_intern_const("hash");
    }
    rb_scan_args(argc, argv, "1:", &pass, &opts);
    rb_get_kwargs(opts, kwargs_ids, 4, 0, kwargs);

    StringValue(pass);
    salt = StringValue(kwargs[0]);
    iters = NUM2INT(kwargs[1]);
    len = NUM2INT(kwargs[2]);
    md = ossl_evp_md_fetch(kwargs[3], &md_holder);

    str = rb_str_new(0, len);
    if (!PKCS5_PBKDF2_HMAC(RSTRING_PTR(pass), RSTRING_LENINT(pass),
                           (unsigned char *)RSTRING_PTR(salt),
                           RSTRING_LENINT(salt), iters, md, len,
                           (unsigned char *)RSTRING_PTR(str)))
        ossl_raise(eKDF, "PKCS5_PBKDF2_HMAC");

    return str;
}