Base64编码字符串到字节数组c#失败

本文关键字：数组 失败 到字节 字符串 编码 编码字符 Base64 | 更新日期: 2023-09-27 18:13:53

我们正在接收来自外部应用程序的base64编码字符串，下面是我们用于将字符串解码为字节数组的代码，但是我们得到一个异常

输入字符串

PHBheW1lbnRSZXNwb25zZT48cmVzcG9uc2VDb2RlPjAwMDA8L3Jlc3BvbnNlQ29kZT48cmVzcG9uc2VDb2RlVGV4dD4wLVN1Y2Nlc3NmdWw8L3Jlc3BvbnNlQ29kZVRleHQ + PHJlc3BvbnNlU3VtbWFyeT5HUkVFTjwvcmVzcG9uc2VTdW1tYXJ5PjxwYXltZW50RXZlbnRJZGVudGlmaWVyPlRYTiAzNjM5PC9wYXltZW50RXZlbnRJZGVudGlmaWVyPjxMaXN0Pjxjb21wb25lbnRJRD5UWE4gMzYzOTwvY29tcG9uZW50SUQ + PGNsaWVudElEPkdPVERJU0UwNjwvY2xpZW50SUQ + PGJhbmtBdXRoQ29kZT5UOjEyMzQ8L2JhbmtBdXRoQ29kZT48YnV5bmV0VHhuSUQ + Mzc1PC9idXluZXRUeG5JRD48L0xpc3Q + PHBheW1lbnRJbnN0cnVtZW50UmVmPjwvcGF5bWVudEluc3 rydw1lbnrszwy + PG1hc2tlZENhcmROdW1iZXI + KioqKioqKioqKioqOTY4NjwvbWFza2VkQ2FyZE51bWJlcj48Y2FyZFR5cGU + TUFTVEVSQ0FSRDwvY2FyZFR5cGU + PGV4cGlyeURhdGU + MDMvMjAxNzwvZXhwaXJ5RGF0ZT48Y3VzdG9tRGF0YT4mbHQ7IVtDREFUQVsmbHQ7P3htbCB2ZXJzaW9uPSIxLjAiIGVuY29kaW5nPSJVVEYtOCI_Jmd0Ow0KJmx0O1RoaXN0bGVDdXN0b21EYXRhIHhtbG5zOnhzZD0iaHR0cDovL3d3dy53My5vcmcvMjAwMS9YTUxTY2hlbWEiIHhtbG5zOnhzaT0iaHR0cDovL3d3dy53My5vcmcvMjAwMS9YTUxTY2hlbWEtaW5zdGFuY2UiJmd0Ow0KICAmbHQ7T3JkZXJJZCZndDtCVFBQMzYzOSZsdDsvT3JkZXJJZCZndDsNCiAgJmx0O0Ftb3 vudcznddsxmjambhq7l0ftb3vudcznddsncizsddsvvghpc3rszun1c3rvburhdgemz3q7xv0mz3q7pc9jdxn0b21eyxrhpjwvcgf5bwvudfjlc3bvbnnlpg

异常

输入不是一个有效的Base-64字符串，因为它包含一个非Base-64字符，两个以上的填充字符，或者填充字符中有一个非法字符。

var inputText = // use the data as shown above
byte[] decodedBytes = Convert.FromBase64String(inputText);

我想知道这是什么错了，为什么它抛出异常，如果我尝试在线转换器，他们能够返回正确的结果。

Base64编码字符串到字节数组c#失败

感谢大家的回复。

在研究了base64编码是如何工作的之后，我得到了这个工作。

下面是我用来修复它的代码。 
var input = new StreamReader(Request.InputStream).ReadToEnd();
        var inputText = "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_Jmd0Ow0KJmx0O1RoaXN0bGVDdXN0b21EYXRhIHhtbG5zOnhzZD0iaHR0cDovL3d3dy53My5vcmcvMjAwMS9YTUxTY2hlbWEiIHhtbG5zOnhzaT0iaHR0cDovL3d3dy53My5vcmcvMjAwMS9YTUxTY2hlbWEtaW5zdGFuY2UiJmd0Ow0KICAmbHQ7T3JkZXJJZCZndDtCVFBQMzYzOSZsdDsvT3JkZXJJZCZndDsNCiAgJmx0O0Ftb3VudCZndDsxMjAmbHQ7L0Ftb3VudCZndDsNCiZsdDsvVGhpc3RsZUN1c3RvbURhdGEmZ3Q7XV0mZ3Q7PC9jdXN0b21EYXRhPjwvcGF5bWVudFJlc3BvbnNlPg";
        inputText = ValidateBase64EncodedString(inputText);
        byte[] decodedBytes = Convert.FromBase64String(inputText);
        string xml = Encoding.UTF8.GetString(decodedBytes);
       private static string ValidateBase64EncodedString(string inputText)
        {
            string stringToValidate = inputText;
            stringToValidate = stringToValidate.Replace('-', '+'); // 62nd char of encoding
            stringToValidate = stringToValidate.Replace('_', '/'); // 63rd char of encoding
            switch (stringToValidate.Length % 4) // Pad with trailing '='s
            {
                case 0: break; // No pad chars in this case
                case 2: stringToValidate += "=="; break; // Two pad chars
                case 3: stringToValidate += "="; break; // One pad char
                default:
                    throw new System.Exception(
             "Illegal base64url string!");
            }
            return stringToValidate;
        }

这是因为您的自定义数据无效。在Base64编码的字符串中，你有一个原始的[CDATA]，很可能没有正确编码。

请注意，如果我取字符串的前684个字符，它会正确转换为:

<paymentResponse><responseCode>0000</responseCode><responseCodeText>0-Successful</responseCodeText><responseSummary>GREEN</responseSummary><paymentEventIdentifier>TXN 3639</paymentEventIdentifier><List><componentID>TXN 3639</componentID><clientID>GOTDISE06</clientID><bankAuthCode>T:1234</bankAuthCode><buynetTxnID>375</buynetTxnID></List><paymentInstrumentRef></paymentInstrumentRef><maskedCardNumber>************9686</maskedCardNumber><cardType>MASTERCARD</cardType><expiryDate>03/2017</expiryDate><customData>&

但是当我们到达customData标签时，所有的地狱都破裂了，我想，这包含CDATA xml内容，这可能不是base64编码。

所以要么离开CDATA内容，或者在将其添加到最终字符串之前对其进行正确编码，以解决问题

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