什么是对的网址安全和文件名安全base64的最佳人选填充字符？ [英] What's the best candidate padding char for url-safe and filename-safe base64?

问题描述

有关官方的base64的填充字符是'='，这可能需要在URL中使用时，必须％的恩codeD。我试图找到最好的填充字符，使我的恩codeD字符串既可以是URL安全的（我将使用EN codeD字符串作为参数值，比如ID = EN codedString ）和文件名安全（我会直接使用EN codeD字符串作为文件名）。

The padding char for the official base64 is '=', which might need to be percent-encoded when used in a URL. I'm trying to find the best padding char so that my encoded string can be both url safe (I'll be using the encoded string as parameter value, such as id=encodedString) AND filename safe (I'll be using the encoded string directly as filename).

点（。）是一个热门人选，它的网址安全的，但它不是完全安全的文件名：的 Windows将不允许其与尾随点结尾的文件名。

Dot ('.') is a popular candidate, it's url safe but it's not exactly filename safe: Windows won't allow a file name which ends with a trailing dot.

！似乎是一个可行的选择，虽然我用Google搜索，并使用它作为填充字符我从来没有见过任何人。有任何想法吗？谢谢！

'!' seems to be a viable choice, although I googled and I've never seen anybody using it as the padding char. Any ideas? Thanks!

更新：我换成+与 - （减号）在我定制的base64编码替换为/与_（下划线）了，所以' - '或'_ 不可用于填充字符了。

Update: I replaced "+" with "-" (minus) and replaced "/" with "_" (underscore) in my customized base64 encoding already, so '-' or '_' is not available for the padding char any more.

推荐答案

最好的解决方案（我已经花了上个月在这个问题上与电子邮件发送网站工作）在所有不使用填充字符（=）

The best solution (I've spent last month working on this problem with an email sending website) is to not use padding character (=) at all

的唯一原因填充字符是有，因为懒得codeRS的。你可以非常容易添加缺少= - >只是做文字上的4％和减去您从4得到的数量，这是多少=你需要在字符串末尾加。下面是C＃code：

The only reason why padding character is there is because of "lazy" decoders. You can extremely easy add missing = -> just do %4 on text and subtract the number you get from 4 and that is how many = you need to add in string end. Here is C# code:

    var pad = 4 - (text.Length % 4);
    if (pad < 4)
        text = text.PadRight(text.Length + pad, '=');

此外，大多数人谁这样做有兴趣的替代+和/与其他URL安全特性......我提议：

Also, most people who do this are interested in replacing + and / with other URL safe character... I propose:

• 替换为 -
  /替换为_

不要使用。因为它可以产生不同的系统/网络服务器疯狂的结果（例如IIS上的Base64 EN codeD字符串不能结束。或IIS将搜索文件）

DO NOT USE . as it can produce crazy results on different systems / web servers (for example on IIS Base64 encoded string can't end with . or IIS will search for the file)

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