带有HTTPS的WebClient.DownloadString"验证或解密失败"

Question

我正在使用Windows 10上的Unity Engine(2017.2.0f3)创建一个游戏,我试图从网页上获取HTML.据我所知,统一使用" 单声道 " C#编译器和运行V2.0(根据运行的结果中),也V5.0.1(根据运行的结果中).我目前正在使用HTML Agility Pack进行解析.当尝试访问HTTP安全网站(例如dictionary.com)时,一切都按预期工作,但无论我做什么,我都无法访问HTTPS安全网站,例如urbandictionary.com(编辑:显然,问题是特定于这个站点,因为在使用导入证书后,可以访问github.com),并且总是收到异常:我知道HTML Agility Pack不支持HTTPS,并根据这个答案编写了我的代码.我已经尝试过这里和这里描述的解决方案,但无济于事.我试着跑,我位于,与,和标志,但同样会抛出异常(如果没有工作,我很怀疑它的便携性,但也许我可以实现我自己的mozroots的版本,评论建议).另外,我被告知,该版本单是统一使用不支持TLS 1.2,这是有问题的.如果没有解决此问题的方法,是否有任何解决方法？mono --versionUnity\Editor\Data\Mono\binmono --versionUnity\Editor\Data\MonoBleedingEdge\binmozrootsTlsException: The authentication or decryption has failed.mozrootsPathTo/Unity/Editor/Data/MonoBleedingEdge/lib/mono/4.5/mozroots--import--sync--quiet

注意:为清晰起见删节

class MyWebClient : WebClient
{
    protected override WebRequest GetWebRequest(Uri address)
    {
        HttpWebRequest request = base.GetWebRequest(address) as HttpWebRequest;
        request.AutomaticDecompression = DecompressionMethods.Deflate | DecompressionMethods.GZip;
        return request;
    }
}

class GetHtml
{
    public static void Get(string url)
    {
        string documentString = new MyWebClient().DownloadString(url);
        ...
    }
}

class CallingClass
{
     public void CallingMethod()
     {
         ServicePointManager.ServerCertificateValidationCallback += (sender, certificate, chain, sslPolicyErrors) => true;
         //With or without the above line ^, the same TlsException is thrown. 
         GetHtml.Get("https://www.urbandictionary.com/define.php?term=example");
         //HTTP works properly, but HTTPS, as in this example, does not.
     }
}

日志如下:

TlsException: The authentication or decryption has failed.
Mono.Security.Protocol.Tls.RecordProtocol.ProcessAlert (AlertLevel alertLevel, AlertDescription alertDesc)
Mono.Security.Protocol.Tls.RecordProtocol.InternalReceiveRecordCallback (IAsyncResult asyncResult)
Rethrow as IOException: The authentication or decryption has failed.
Mono.Security.Protocol.Tls.SslStreamBase.AsyncHandshakeCallback (IAsyncResult asyncResult)
Rethrow as WebException: Error getting response stream (Write: The authentication or decryption has failed.): SendFailure
System.Net.HttpWebRequest.EndGetResponse (IAsyncResult asyncResult)
System.Net.HttpWebRequest.GetResponse ()
System.Net.WebClient.GetWebResponse (System.Net.WebRequest request)
System.Net.WebClient.DownloadDataCore (System.Uri address, System.Object userToken)

编辑:我已经尝试更新运行时版本.唯一的选择是在Project Settings-> Player菜单中从.Net 3.5更改为4.6,这是实验性的.代码运行时我仍然会遇到异常,但输出日志略有不同.

TlsException: The authentication or decryption has failed.
Mono.Security.Protocol.Tls.RecordProtocol.EndReceiveRecord (System.IAsyncResult asyncResult) (at <eb1224ae7b184cd09343d47f8a05481b>:0)
Mono.Security.Protocol.Tls.SslClientStream.SafeEndReceiveRecord (System.IAsyncResult ar, System.Boolean ignoreEmpty) (at <eb1224ae7b184cd09343d47f8a05481b>:0)
Mono.Security.Protocol.Tls.SslClientStream.NegotiateAsyncWorker (System.IAsyncResult result) (at <eb1224ae7b184cd09343d47f8a05481b>:0)
Rethrow as IOException: The authentication or decryption has failed.
Mono.Security.Protocol.Tls.SslClientStream.EndNegotiateHandshake (System.IAsyncResult result) (at <eb1224ae7b184cd09343d47f8a05481b>:0)
Mono.Security.Protocol.Tls.SslStreamBase.AsyncHandshakeCallback (System.IAsyncResult asyncResult) (at <eb1224ae7b184cd09343d47f8a05481b>:0)
Rethrow as IOException: The authentication or decryption has failed.
Mono.Security.Protocol.Tls.SslStreamBase.EndRead (System.IAsyncResult asyncResult) (at <eb1224ae7b184cd09343d47f8a05481b>:0)
Mono.Net.Security.Private.LegacySslStream.EndAuthenticateAsClient (System.IAsyncResult asyncResult) (at <344dc4d3f1ad41809df78607b6121a41>:0)
Mono.Net.Security.Private.LegacySslStream.AuthenticateAsClient (System.String targetHost, System.Security.Cryptography.X509Certificates.X509CertificateCollection clientCertificates, System.Security.Authentication.SslProtocols enabledSslProtocols, System.Boolean checkCertificateRevocation) (at <344dc4d3f1ad41809df78607b6121a41>:0)
Mono.Net.Security.MonoTlsStream.CreateStream (System.Byte[] buffer) (at <344dc4d3f1ad41809df78607b6121a41>:0)
System.Net.WebConnection.CreateStream (System.Net.HttpWebRequest request) (at <344dc4d3f1ad41809df78607b6121a41>:0)
Rethrow as WebException: Error: SecureChannelFailure (The authentication or decryption has failed.)
System.Net.WebClient.DownloadDataInternal (System.Uri address, System.Net.WebRequest& request) (at <344dc4d3f1ad41809df78607b6121a41>:0)
System.Net.WebClient.DownloadString (System.Uri address) (at <344dc4d3f1ad41809df78607b6121a41>:0)
System.Net.WebClient.DownloadString (System.String address) (at <344dc4d3f1ad41809df78607b6121a41>:0)

Answer 1

经过一番严格的研究后发现，Unity（2017.2.0f3）当前使用的Mono版本不支持TLS 1.2，正如开发人员在这里解释的那样。此外，对异常日志的仔细检查表明，在内部，正在使用旧后端： 而不是. 截至目前，唯一的解决方案将涉及第三方库或解决方法。Mono.Net.Security.Private.LegacySslStreamMono.Net.Security.Private.SslStream

感谢@Evk 为我指明了正确的方向。