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POUnable to decode Base-64 URLs
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copied!<p>I have an application that builds an HTML email. Included in the content is an encoded URL parameter that might, for example, contain a promotional code or product reference. The email is generated by a Windows service (essentially a console application) and the link, when clicked is handled by an MVC web site. Here is the code for creating the email link:</p> <pre><code>string CreateLink(string domain, string code) { // code == "xyz123" string encrypted = DES3Crypto.Encrypt(code); // H3uKbdyzrUo= string urlParam = encrypted.EncodeBase64(); // SDN1S2JkeXpyVW890 return domain + "/" + urlParam; } </code></pre> <p>The action method on the MVC controller is constructed as follows:</p> <pre><code>public ActionResult Index(string id) { string decoded = id.DecodeBase64(); string decrypted = DES3Crypto.Decrypt(decoded); ... } </code></pre> <p>In all our testing, this mechanism has worked as expected, however, now we have gone live we are seeing around a 4% error rate where the conversion from base-64 fails with the following exception:</p> <p><em>The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or a non-white space character among the padding characters.</em></p> <p>The id parameter from the url 'looks' OK. The problem appears to be with the EncodeBase64/DecodeBase64 methods that are failing as DecodeBase64 method returns a 'garbled' string such as "�nl��□��7y�b�8�sJ��=" on the failed links.</p> <p>Furthermore, most of the errors are from IE6 user agents leading me to think this is a character encoding problem but I don't see why.</p> <p>For reference, here is the code for my base-64 URL encoding:</p> <pre><code> public static string EncodeBase64(this string source) { byte[] bytes = Encoding.UTF8.GetBytes(source); string encodedString = HttpServerUtility.UrlTokenEncode(bytes); return encodedString; } public static string DecodeBase64(this string encodedString) { byte[] bytes = HttpServerUtility.UrlTokenDecode(encodedString); string decodedString = Encoding.UTF8.GetString(bytes); return decodedString; } </code></pre> <p>Any advice would be much appreciated.</p>

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