dcinside_servicecode.cs

using System.Text.RegularExpressions;

// $('input[name="service_code"]').val()

string _d(string r)
{
    int a, e, n, t, f, d, h;
    string i = "yL/M=zNa0bcPQdReSfTgUhViWjXkYIZmnpo+qArOBslCt2D3uE4Fv5G6wH178xJ9K";
    string o = "";
    int c = 0;

    r = Regex.Replace(r, @"[^A-Za-z0-9+/=]", "");
    for (; c < r.Length;)
    {
        t = i.IndexOf(r[c++]);
        f = i.IndexOf(r[c++]);
        d = i.IndexOf(r[c++]);
        h = i.IndexOf(r[c++]);
        a = t << 2 | f >> 4;
        e = (15 & f) << 4 | d >> 2;
        n = (3 & d) << 6 | h;
        o += (char)a;
        if (64 != d) o += (char)e;
        if (64 != h) o += (char)n;
    }

    return o;
}

string _f(string r, string _r)
{
    var _rs = _r.Split(',');
    var c = "";
    for (int n = 0; n < _rs.Length; n++)
    {
        var tc = (2 * (float.Parse(_rs[n]) - n - 1) / (13 - n - 1));
        c += (char)tc;
    }
    return Regex.Replace(r, @"(.{10})$", c);
}

string convert_r(string tvl)
{
    var charArr = tvl.ToCharArray();
    var fi = tvl[0] - '0';
    fi = fi > 5 ? fi - 5 : fi + 4;
    charArr[0] = (char)(fi + '0');
    return new string(charArr);
}

string convertServiceCode(string serviceCode, string rRaw)
{
    var _r = _d(rRaw);
    _r = convert_r(_r);
    return _f(serviceCode, _r);
}

var testcases = new[]
{
    new ServiceCodeTestCase
    {
        R = "QgnHPM0HQ4w5PM05R/u4dMYtQ+0HPM=6d4w5PMQEQ4uEQ+ntQg0FPMnFP+UK",
        InputServiceCode = "21ac6d96ad152e8f15a05b7350a2475909d19bcedeba9d4face8115e9bc1fa4e69723ec5ce0bf0b1105e9ea3edaaf17e527fd210ecee3a7073209b578a56acb19e62d070492b9639fe2fd4d616f4fa0ec1aa47e651836a74cd0c1b3d0eb6484496238f01f4db97d8e801ac3e878a1c25233d6089936119bf33db1086914531ab77050029d1cdfbe327b8409f175f684612954bebde386fd9999e19a64f0f69a7607cbb0a072e6a4785c04de95eca4939e2f3ba1a5f8483570a515b7e5601bc6ca0fdcb6ec30399ac48a1b33f81f091",
        ExpectedServiceCode = "21ac6d96ad152e8f15a05b7350a2475909d19bcedeba9d4face8115e9bc1fa4e69723ec5ce0bf0b1105e9ea3edaaf17e527fd210ecee3a7073209b578a56acb19e62d070492b9639fe2fd4d616f4fa0ec1aa47e651836a74cd0c1b3d0eb6484496238f01f4db97d8e801ac3e878a1c25233d6089936119bf33db1086914531ab77050029d1cdfbe327b8409f175f684612954bebde386fd9999e19a64f0f69a7607cbb0a072e6a4785c04de95eca4939e2f3ba1a5f8483570a515b7e5601bc6ca0fdcb6ec30399ac48a1b53681f091"
    },
    new ServiceCodeTestCase
    {
        R = "QgnHPMQEdTw5PM0vR/u4Q+ytdMy5PM=wR/uEdgStQgQuP+UtQ+yHPM=5dTw5",
        InputServiceCode = "21ac6d96ad152e8f15a05b7350a2475909d19bcedeba9d4face8115e9bc1fa4e6e7a3dcac30cf0b1105e9ea3edaaf17e98126fc2f6a38e55e7d8d3827b417a0c3b34e3b8c1a5e426e39ad97e7a9a3855469435c07415a913e087412a64ff0286a18dcadf4edf8c99342f71e55465cc9cc21436f1bf11d13988b17476a4d9c8d43b1569a87ff77fe671917256da7667c1332adc9143d0e742789e0d0af777711f0c603f82fab577650ddd8cef65d1b092be3d40817e391f36650f38ab9d801dccdabe18d411da",
        ExpectedServiceCode = "21ac6d96ad152e8f15a05b7350a2475909d19bcedeba9d4face8115e9bc1fa4e6e7a3dcac30cf0b1105e9ea3edaaf17e98126fc2f6a38e55e7d8d3827b417a0c3b34e3b8c1a5e426e39ad97e7a9a3855469435c07415a913e087412a64ff0286a18dcadf4edf8c99342f71e55465cc9cc21436f1bf11d13988b17476a4d9c8d43b1569a87ff77fe671917256da7667c1332adc9143d0e742789e0d0af777711f0c603f82fab577650ddd8cef65d1b092be3d40817e391f36650f38ab9d801dccdab910d411da"
    }
};

foreach (var tc in testcases)
{
    Console.WriteLine(tc.InputServiceCode);
    var result = convertServiceCode(tc.InputServiceCode, tc.R);
    Console.WriteLine(result);

    if (result == tc.ExpectedServiceCode)
    {
        Console.WriteLine("PASS\n");
    }
    else
    {
        Console.WriteLine("FAIL\n");
    }
}

class ServiceCodeTestCase
{
    public string? R { get; set; }
    public string? InputServiceCode { get; set; }
    public string? ExpectedServiceCode { get; set; }
}