ios9 self signed certificate and app transport security - ssl

Question

I've spent a while trying to get this working. I have an API that I'm connecting to that i'm trying to switch to SSL with self signed certificates. I have control on the server and app.
I generated a self signed cert according to this:
https://kyup.com/tutorials/create-ssl-certificate-nginx/
sudo openssl genrsa -des3 -out ssl.key 2048
sudo openssl req -new -key ssl.key -out ssl.csr
sudo cp ssl.key ssl.key.orig & sudo openssl rsa -in ssl.key.orig -out ssl.key
sudo openssl x509 -req -days 365 -in ssl.csr -signkey ssl.key -out ssl.crt
I've tried some config options on the server (NGINX)
ssl on;
ssl_certificate /etc/nginx/ssl/ssl.crt;
ssl_certificate_key /etc/nginx/ssl/ssl.key;
ssl_session_timeout 5m;
ssl_protocols SSLv2 SSLv3 TLSv1 TLSv1.1 TLSv1.2;
ssl_ciphers HIGH:!aNULL:!MD5;
#ssl_ciphers "EECDH+ECDSA+AESGCM EECDH+aRSA+AESGCM EECDH+ECDSA+SHA384 EECDH+ECDSA+SHA256 EECDH+aRSA+SHA384 EECDH+aRSA+SHA256 EECDH+aRSA+RC4 EECDH EDH+aRSA RC4 !aNULL !eNULL !LOW !3DES !MD5 !EXP !PSK !SRP !DSS";
ssl_prefer_server_ciphers on;
And on the client side I've tried some different options with ATS:
<key>NSAppTransportSecurity</key>
<dict>
<key>NSAllowsArbitraryLoads</key>
<true/>
</dict>
and
<key>NSAppTransportSecurity</key>
<dict>
<key>NSAllowsArbitraryLoads</key>
<true/>
<key>NSExceptionDomains</key>
<dict>
<key>test.example.com (NOT REALLY MY DOMAIN)</key>
<dict>
<key>NSExceptionAllowsInsecureHTTPLoads</key>
<true/>
</dict>
</dict>
</dict>
and
<key>NSAppTransportSecurity</key>
<dict>
<key>NSAllowsArbitraryLoads</key>
<true/>
<key>NSExceptionDomains</key>
<dict>
<key>test.example.com (NOT REALLY MY DOMAIN)</key>
<dict>
<key>NSExceptionAllowsInsecureHTTPLoads</key>
<true/>
<key>NSExceptionRequiresForwardSecrecy</key>
<false/>
<key>NSExceptionMinimumTLSVersion</key>
<string>TLSv1.1</string>
</dict>
</dict>
</dict>
Depending on different ATS options I get errors:
An SSL error has occurred and a secure connection to the server cannot be made.
or
NSURLSession/NSURLConnection HTTP load failed (kCFStreamErrorDomainSSL, -9813)
The certificate for this server is invalid. You might be connecting to a server that is pretending to be “MYDOMAIN” which could put your confidential information at risk.
Any ideas? Anyone else struggle with self signed certs?
P.S. I'm on OS X 10.11.2 Beta, Xcode 7.1.1

Answer 1

I figured out the issue. It has nothing to do with App Transport Security. I had to make sure that iOS trusts the certificate since it's not from a trusted authority.
The old school way of doing this by overriding NSURLRequest.allowsAnyHTTPSCertificateForHost doesn't work.
Since i'm using NSURLSession you have to do it with this:
- (id) init {
self = [super init];
NSURLSessionConfiguration * config = [NSURLSessionConfiguration defaultSessionConfiguration];
self.session = [NSURLSession sessionWithConfiguration:config delegate:self delegateQueue:[NSOperationQueue mainQueue]];
return self;
}
- (void) URLSession:(NSURLSession *)session didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition, NSURLCredential * _Nullable))completionHandler {
completionHandler(NSURLSessionAuthChallengeUseCredential,[NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust]);
}

Answer 2

just need add .cer to SecTrust
func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: #escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Swift.Void) {
if (challenge.protectionSpace.authenticationMethod == NSURLAuthenticationMethodServerTrust) {
if let trust = challenge.protectionSpace.serverTrust,
let pem = Bundle.main.path(forResource: "https", ofType: "cer"),
let data = NSData(contentsOfFile: pem),
let cert = SecCertificateCreateWithData(nil, data) {
let certs = [cert]
SecTrustSetAnchorCertificates(trust, certs as CFArray)
completionHandler(URLSession.AuthChallengeDisposition.useCredential, URLCredential(trust: trust))
return
}
}
// Pinning failed
completionHandler(URLSession.AuthChallengeDisposition.cancelAuthenticationChallenge, nil)
}