OpenSSL::KDF.pbkdf2_hmac

static VALUE
kdf_pbkdf2_hmac(int argc, VALUE *argv, VALUE self)
{
    VALUE pass, salt, opts, kwargs[4], str, md_holder, pass_tmp, salt_tmp;
    static ID kwargs_ids[4];
    int passlen, saltlen, 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);
    passlen = RSTRING_LENINT(pass);
    saltlen = RSTRING_LENINT(salt);
    str = rb_str_new(NULL, len);
    struct pbkdf2_hmac_args args = {
        .pass = ALLOCV(pass_tmp, passlen),
        .passlen = passlen,
        .salt = ALLOCV(salt_tmp, saltlen),
        .saltlen = saltlen,
        .iters = iters,
        .md = md,
        .len = len,
        .out = (unsigned char *)RSTRING_PTR(str),
    };
    memcpy(args.pass, RSTRING_PTR(pass), passlen);
    memcpy(args.salt, RSTRING_PTR(salt), saltlen);
    if (!rb_thread_call_without_gvl(pbkdf2_hmac_nogvl, &args, NULL, NULL))
        ossl_raise(eKDF, "PKCS5_PBKDF2_HMAC");
    OPENSSL_cleanse(args.pass, passlen);
    ALLOCV_END(pass_tmp);
    ALLOCV_END(salt_tmp);
    return str;
}