NSUrlConnection sendAsynchronousRequest and self-signed certificates

Question

I'm writing some API code that does http requests, and I've been using [NSUrlConnection:sendAsynchronousRequest:queue:completionHandler] for the calls, as it makes it pretty easy to write simple handlers, and also so that I don't have to have different classes with different delegates for each call.

The problem that I'm having is that it seems that the only way to accept self-signed certificates is to have a delegate that implements a couple of functions saying that the certificate is okay. Is there any way to do this with the asynchronous method that uses blocks?

Answer 1

No, but the delegate calls are not all that hard. This is the code you need:

1) Make this a file static

static CFArrayRef certs;

2) DO this in your initialize:

    // I had a crt certificate, needed a der one, so found this site:
    // http://fixunix.com/openssl/537621-re-der-crt-file-conversion.html
    // and did this from Terminal: openssl x509 -in crt.crt -outform der -out crt.der
    NSString *path = [[NSBundle mainBundle] pathForResource:@"<your name>" ofType:@"der"];
    assert(path);
    NSData *data = [NSData dataWithContentsOfFile:path];
    assert(data);

    SecCertificateRef rootcert = SecCertificateCreateWithData(NULL, (__bridge CFDataRef)data);
    if(rootcert) {
        const void *array[1] = { rootcert };
        certs = CFArrayCreate(NULL, array, 1, &kCFTypeArrayCallBacks);
        CFRelease(rootcert);    // for completeness, really does not matter 
    } else {
        NSLog(@"BIG TROUBLE - ROOT CERTIFICATE FAILED!");
    }

3) Then add this method:

- (void)connection:(NSURLConnection *)conn didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
{
#pragma unused(conn)
    // NSLog(@"didReceiveAuthenticationChallenge %@ FAILURES=%zd", [[challenge protectionSpace] authenticationMethod], (ssize_t)[challenge previousFailureCount]);

    /* Setup */
    NSURLProtectionSpace *protectionSpace   = [challenge protectionSpace];
    assert(protectionSpace);
    SecTrustRef trust                       = [protectionSpace serverTrust];
    assert(trust);
    CFRetain(trust);                        // Don't know when ARC might release protectionSpace
    NSURLCredential *credential             = [NSURLCredential credentialForTrust:trust];

    BOOL trusted = NO;
    OSStatus err;
    SecTrustResultType trustResult = 0;

    err = SecTrustSetAnchorCertificates(trust, certs);
    if (err == noErr) {
        err = SecTrustEvaluate(trust, &trustResult);
        if(err == noErr) {
        // http://developer.apple.com/library/mac/#qa/qa1360/_index.html
            switch(trustResult) {
            case kSecTrustResultProceed:
            case kSecTrustResultConfirm:
            case kSecTrustResultUnspecified:
                trusted = YES;
                break;
            }       
        }
    }
    CFRelease(trust);

    // Return based on whether we decided to trust or not
    if (trusted) {
        [[challenge sender] useCredential:credential forAuthenticationChallenge:challenge];
    } else {
        NSLog(@"Trust evaluation failed");
        [[challenge sender] cancelAuthenticationChallenge:challenge];
    }
}