检查，如果PDF使用iTextSharp的密码保护 [英] checking if pdf is password protected using itextsharp

问题描述

我要检查，如果一个PDF文件有密码保护或不查看。这就是我想知道如果PDF文件有用户密码或没有。

I want to check if a pdf file is password protected or not to view. That is i want to know if the pdf file has user password or not.

我发现在一些论坛上一些帮助它使用 isencrypted 的功能，但它并没有给出正确的答案。

I found some help in some forum about it to use isencrypted function but it does not give correct answer.

是否有可能来检查PDF是密码保护？

Is it possible to check if a pdf is password protected?

推荐答案

与使用 PdfReader.IsEncrypted 方法的问题是，如果你试图实例化一个<$ C在PDF $ C> PdfReader 需要密码 - 你不提供该密码 - 你会得到一个 BadPasswordException 。

The problem with using the PdfReader.IsEncrypted method is that if you attempt to instantiate a PdfReader on a PDF that requires a password - and you don't supply that password - you'll get a BadPasswordException.

牢记这一点，你可以写这样的方法：

Keeping this in mind you can write a method like this:

public static bool IsPasswordProtected(string pdfFullname) {
    try {
        PdfReader pdfReader = new PdfReader(pdfFullname);
        return false;
    } catch (BadPasswordException) {
        return true;
    }
}

请注意，如果您提供的密码无效，你会得到同样的 BadPasswordException试图构建一个 PdfReader 对象时。您可以使用它来创建一个验证PDF文件的密码的方法：

Note that if you supply an invalid password you'll get the same BadPasswordException when attempting to construct a PdfReader object. You can use this to create a method that validates a PDF's password:

public static bool IsPasswordValid(string pdfFullname, byte[] password) {
    try {
        PdfReader pdfReader = new PdfReader(pdfFullname, password);
        return false;
    } catch (BadPasswordException) {
        return true;
    }
}

当然它是丑陋的，但据我所知，这是检查的唯一途径，如果PDF是密码保护。希望有人会建议一个更好的解决方案。

Sure it's ugly but as far as I know this is the only way to check if a PDF is password protected. Hopefully someone will suggest a better solution.

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