由于以下错误消息，我们无法使用WebRequest连接到HTTPS服务器:
请求被中止:无法创建SSL/TLS安全通道。
我们知道服务器没有有效的HTTPS证书，但为了绕过这个问题，我们使用下面的代码，我们从另一个StackOverflow帖子:
private void Somewhere() {
ServicePointManager.ServerCertificateValidationCallback += new RemoteCertificateValidationCallback(AlwaysGoodCertificate);
}
private static bool AlwaysGoodCertificate(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors policyErrors) {
return true;
}
问题是服务器从未验证证书，并出现上述错误而失败。有人知道我该怎么做吗?
我应该提到的是，我和一个同事几周前进行了测试，它运行得很好，与我上面写的类似。我们发现的唯一“主要区别”是，我用的是Windows 7，而他用的是Windows XP。这会改变什么吗?
我在Windows 2008服务器上的. net 4.5.2 Winform应用程序上得到了相同的错误。
我尝试了以下修复方法:
ServicePointManager。SecurityProtocol = SecurityProtocolType. tls1 |安全协议类型。Tls11 | SecurityProtocolType.Tls12;
但这并没有起作用，错误的发生次数仍然存在。
根据上面的答案之一，是否必须覆盖注册表的SchUseStrongCrypto键。如果我设置这个键会有什么副作用吗?
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework\v4.0.30319]
"SchUseStrongCrypto"=dword:00000001
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319]
"SchUseStrongCrypto"=dword:00000001
在我的情况下，这个异常的根源是在代码的某些时候，下面的代码被调用:
ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;
这真的很糟糕。它不仅指示. net使用不安全的协议，而且还会影响在您的应用域中随后发出的每一个新的WebClient(和类似的)请求。(请注意，传入的web请求在你的ASP中不受影响。NET应用程序，但新的WebClient请求，如与外部web服务对话，是)。
在我的情况下，它实际上并不需要，所以我可以删除该语句，所有其他的web请求重新开始正常工作。根据我在其他地方的阅读，我了解到一些事情:
This is a global setting in your appdomain, and if you have concurrent activity, you can't reliably set it to one value, do your action, and then set it back. Another action may take place during that small window and be impacted.
The correct setting is to leave it default. This allows .NET to continue to use whatever is the most secure default value as time goes on and you upgrade frameworks. Setting it to TLS12 (which is the most secure as of this writing) will work now but in 5 years may start causing mysterious problems.
If you really need to set a value, you should consider doing it in a separate specialized application or appdomain and find a way to talk between it and your main pool. Because it's a single global value, trying to manage it within a busy app pool will only lead to trouble. This answer: https://stackoverflow.com/a/26754917/7656 provides a possible solution by way of a custom proxy. (Note I have not personally implemented it.)
确保ServicePointManager设置是在创建HttpWebRequest之前完成的，否则它将无法工作。
工作原理:
ServicePointManager.Expect100Continue = true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls
| SecurityProtocolType.Tls11
| SecurityProtocolType.Tls12
| SecurityProtocolType.Ssl3;
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://google.com/api/")
失败:
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://google.com/api/")
ServicePointManager.Expect100Continue = true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls
| SecurityProtocolType.Tls11
| SecurityProtocolType.Tls12
| SecurityProtocolType.Ssl3;
在我的例子中，当一个Windows服务试图连接到一个web服务时，我遇到了这个问题。在Windows事件中，我终于找到了一个错误代码。
事件ID 36888(通道)被引发:
The following fatal alert was generated: 40. The internal error state is 808.
最后，它与Windows热修复有关。在我的例子中是KB3172605和KB3177186
vmware论坛提出的解决方案是在windows中添加一个注册表项。添加以下注册表后，所有工作正常。
[HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ \控制SecurityProviders \ SCHANNEL \ KeyExchangeAlgorithms \ diffie - hellman)
“ClientMinKeyBitLength”= dword: 00000200
显然，这与客户端https握手中缺失的值有关。
列出你的Windows HotFix:
wmic qfe list
解决方案线程:
https://communities.vmware.com/message/2604912#2604912
希望对大家有所帮助。
