ios9 self signed certificate and app transport security

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]);
}