Swift iOS Client Certificate Authentication

Question

The web service I want to consume requires a client certificate. How can I send my certificate to it?

To further elaborate I don\'t understand how to create the

Answer 1

In order to respond to the authentication challenge you need to extract the identity from your client certificate.

struct IdentityAndTrust {

    var identityRef:SecIdentityRef
    var trust:SecTrustRef
    var certArray:NSArray
}

func extractIdentity(certData:NSData, certPassword:String) -> IdentityAndTrust {

    var identityAndTrust:IdentityAndTrust!
    var securityError:OSStatus = errSecSuccess

    var items:Unmanaged?
    let certOptions:CFDictionary = [ kSecImportExportPassphrase.takeRetainedValue() as String: certPassword ];

    // import certificate to read its entries
    securityError = SecPKCS12Import(certData, certOptions, &items);

    if securityError == errSecSuccess {

        let certItems:CFArray = items?.takeUnretainedValue() as CFArray!;
        let certItemsArray:Array = certItems as Array
        let dict:AnyObject? = certItemsArray.first;

        if let certEntry:Dictionary = dict as? Dictionary {

            // grab the identity
            let identityPointer:AnyObject? = certEntry["identity"];
            let secIdentityRef:SecIdentityRef = identityPointer as! SecIdentityRef!;

            // grab the trust
            let trustPointer:AnyObject? = certEntry["trust"];
            let trustRef:SecTrustRef = trustPointer as! SecTrustRef;

            // grab the certificate chain
            var certRef:Unmanaged?
            SecIdentityCopyCertificate(secIdentityRef, &certRef);
            let certArray:NSMutableArray = NSMutableArray();
            certArray.addObject(certRef?.takeRetainedValue() as SecCertificateRef!);

            identityAndTrust = IdentityAndTrust(identityRef: secIdentityRef, trust: trustRef, certArray: certArray);
        }
    }

    return identityAndTrust;
}

In NSURLSessionDelegate respond to the authentication challenge like this:

public func URLSession(session: NSURLSession, didReceiveChallenge challenge: NSURLAuthenticationChallenge, completionHandler: (NSURLSessionAuthChallengeDisposition, NSURLCredential?) -> Void) {

    let bundle:NSBundle = NSBundle(forClass: self.dynamicType);
    let bundleCertPath:NSString = bundle.pathForResource("clientCertificateName", ofType: "p12")!;
    let certData:NSData = NSData(contentsOfFile: bundleCertPath as String)!;
    let identityAndTrust:IdentityAndTrust = self.certificateHelper.extractIdentity(certData, certPassword: "C00lp@assword");

    if challenge.protectionSpace.authenticationMethod == NSURLAuthenticationMethodClientCertificate {

        let urlCredential:NSURLCredential = NSURLCredential(
                identity: identityAndTrust.identityRef,
                certificates: identityAndTrust.certArray as [AnyObject],
                persistence: NSURLCredentialPersistence.ForSession);

        completionHandler(NSURLSessionAuthChallengeDisposition.UseCredential, urlCredential);


    } else {

        // nothing here but us chickens
    }
}