HOWQ WETIRE MY OWEN HASH?!

string hash(string a, string key)
{
    var ret = "";
    var add = "";
    a = a.ToLowerInvariant();
    key = key.ToLowerInvariant();
    var i = 0;
    while (i < a.Length && i < 20)
    {
        var _5 = a[i];
        var _6 = key[i];
        var _7 = (char)(((uint)_5 + (uint)_6) % 26 + 65);
        ret += _7;
        i++;
    }
    if (i < 20)
    {
        while (i < 20)
        {
            ret += "1";
            i++;
        }
    }
    ret += add;
    return ret;
}