C# HTTPS请求上的Mono SecureChannel失败

运行以下行：

new HttpClient().GetAsync(url).GetAwaiter().GetResult(); // url being an https endpoint with a valid certificate when I browse to the image from a browser

我得到以下例外情况：

Error: SecureChannelFailure (The authentication or decryption has failed.)

Error: ConnectFailure (TLS Support not available.)

我尝试添加

ServicePointManager

解决方案：

ServicePointManager.ServerCertificateValidationCallback += (a, b, c, d) => true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3 | SecurityProtocolType.Tls;

单独、一起以及与此回调实现一起：

public static bool ValidationCallback(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
{
    if (sslPolicyErrors == SslPolicyErrors.None)
        return true;

    var isOk = true;

    for (int i = 0; i < chain.ChainStatus.Length; i++)
        if (chain.ChainStatus[i].Status != X509ChainStatusFlags.RevocationStatusUnknown)
        {
            chain.ChainPolicy.RevocationFlag = X509RevocationFlag.EntireChain;
            chain.ChainPolicy.RevocationMode = X509RevocationMode.Online;
            chain.ChainPolicy.UrlRetrievalTimeout = new TimeSpan(0, 1, 0);
            chain.ChainPolicy.VerificationFlags = X509VerificationFlags.AllFlags;

            var chainIsValid = chain.Build((X509Certificate2)certificate);

            if (!chainIsValid)
                isOk = false;
        }

    return isOk;
}

我正在Linux上使用Mono 4.4.1，我还尝试导入运行以下操作的证书：

mozroots --import --sync --url "http://hg.mozilla.org/releases/mozilla-release/raw-file/default/security/nss/lib/ckfw/builtins/certdata.txt"

---

Mono4.4.1不包括BTL，请使用Mono5.x