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Bug in Xamarin.IOS SSLStream
Description of Problem:
In SSLStream constructor one can provide a RemoteCertificateValidationCallback. This callback
has a X509Certificate as its third parameter.
Since the intruduction of Apple TLS this parameter can no longer be casted to ha X509Certificate2.
This is a big issue since in the validation callback I need to check the thumbprint of the certificate to make sure it is correct. I can no longer do that.
IF in project settings I set the SSL/TLS implementation to Mono (TLS 1.0) then it works again.
Steps to reproduce the problem:
1. Set SSL/TLS implementation to Apple TLS
2. Create new SSLStream from a tcp-stream.
3. Provide a RemoteCertificateValidationCallback delegate
certificate is a X509Certificate certificate in RemoteCertificateValidationCallback
certificate is a X509Certificate2 certificate in RemoteCertificateValidationCallback
How often does this happen?
Please include all version informations and a test case if possible that demonstrates your issue.
The easiest way to get exact version information is to use the
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Xamarin Studio Community
Version 6.0 (build 5174)
Installation UUID: 6ad335c5-270d-4a92-9e12-015e92f249de
Mono 4.4.0 (mono-4.4.0-branch-c7-baseline/5995f74) (64-bit)
GTK+ 2.24.23 (Raleigh theme)
Package version: 404000182
Location: /Applications/Xamarin Profiler.app/Contents/MacOS/Xamarin Profiler
Version: 220.127.116.11 (Xamarin Studio Community)
Android SDK: /Users/johannorberg/Library/Developer/Xamarin/android-sdk-macosx
Supported Android versions:
2.3 (API level 10)
4.0.3 (API level 15)
4.1 (API level 16)
4.4 (API level 19)
5.1 (API level 22)
6.0 (API level 23)
SDK Tools Version: 24.4.1
SDK Platform Tools Version: 23.1
SDK Build Tools Version: 23.0.2
Java SDK: /usr
java version "1.8.0_31"
Java(TM) SE Runtime Environment (build 1.8.0_31-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.31-b07, mixed mode)
Android Designer EPL code available here:
Xamarin Android Player
Apple Developer Tools
Xcode 7.3.1 (10188.1)
Version: 18.104.22.1683 (Xamarin Studio Community)
Build date: 2016-06-01 21:23:15-0400
Release ID: 600005174
Git revision: 694a75f040b7f2309bc43d4f78a3a6572ca898bf
Build date: 2016-06-01 17:28:08-04
Xamarin addins: 33f406fa2dcf214012c78cb846585f062b2e1d24
Build lane: monodevelop-lion-cycle7-baseline
Mac OS X 10.11.4
Darwin Johans-MBP-2.mydomain.example 15.4.0 Darwin Kernel Version 15.4.0
Fri Feb 26 22:08:05 PST 2016
@Johan you cannot assume a specific subclass will be provided by the delegate callback when it's called.
The .NET API  contract only guarantee a `X509Certificate`. The exact type is an implementation details and can change over time as we modify our implementation(s), like it just happened for AppleTLS support.
If you need an `X509Certificate2` instance then you must do the work yourself, e.g.
// The following method is invoked by the RemoteCertificateValidationDelegate.
public static bool ValidateServerCertificate(
// quick check to see if we're provided with what we need
X509Certificate2 x2 = (certificate as X509Certificate2);
// if we're not then we must create the instance of the type we need
if (x2 == null)
x2 = new X509Certificate2 (certificate.GetRawData ());
Ok great, not a bug then, just a difference in the implementation. Thank you.