在 PHP 和 C# 之间解码 base64 文件内容

我需要将AES加密的base64编码文件从PHP提供给C#客户端（Mono，在各种平台上）。我已经成功地让 AES 加密/解密工作正常，但一旦我尝试 base64 编码/解码，我就遇到了麻烦。下面的两个示例都禁用了 AES，因此这不应该是一个因素。

我最简单的测试用例，一个 Hello World 字符串，工作正常：

PHP 服务输出-

// Save encoded data to file
$data = base64_encode("Hello encryption world!!");
$file = fopen($targetPath, 'w');
fwrite($file, $data);
fclose($file);
// Later on, serve the file
header("Pragma: public");
header("Expires: 0");
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
header("Cache-Control: private",false);
header("Content-Type: application/octet-stream");
header("Content-Disposition: attachment; filename=".basename($product->PackageFilename($packageId)));
header("Content-Transfer-Encoding: binary");
header("Content-Length: ".filesize($targetPath));
ob_clean();
flush();
$handle = fopen($targetPath, "r");
fpassthru($handle);
fclose($handle);

C# 解码和使用-

StreamReader reader = new StreamReader(stream);
char[] buffer = DecodeBuffer;
string decoded = "";
int read = 0;
while (0 < (read = reader.Read(buffer, 0, DecodeBufferSize)))
{
    byte[] decodedBytes = Convert.FromBase64CharArray(buffer, 0, read);
    decoded += System.Text.Encoding.UTF8.GetString(decodedBytes);
}
Log(decoded); // Correctly logs "Hello encryption world!!"

但是，一旦我开始尝试对文件的内容做同样的事情，Convert.FromBase64CharArray就会抛出FormatException：找到无效字符：

PHP 服务输出-

// Save encoded data to file
$data = base64_encode(file_get_contents($targetPath));
$file = fopen($targetPath, 'w');
fwrite($file, $data);
fclose($file);
// Later on, serve the file
// Same as above

C# 解码和使用-

using (Stream file = File.Open(zipPath, FileMode.Create))
{
using (StreamReader reader = new StreamReader(stream))
{
    char[] buffer = DecodeBuffer;
    byte[] decodedBytes;
    int read = 0;
    while (0 < (read = reader.Read(buffer, 0, DecodeBufferSize)))
    {
        // Throws FormatException: Invalid character found
                    decodedBytes = Convert.FromBase64CharArray(buffer, 0, read);
        file.Write(decodedBytes, 0, decodedBytes.Length);
    }
}
}

是否应该对较大的数据进行某种额外的处理才能使 base64 有效？使用大型二进制数据这样做是否可能只是不合适 - 如果是这样，您还将如何防止不安全传输的字符的潜在问题？