iOS NSURLAuthenticationMethodClientCertificate 未请求与 ActiveSync 服务器

Question

我正在尝试在我正在开发的 ActiveSync 客户端中实施证书身份验证。使用证书身份验证的代码可能有效，但到目前为止，服务器，或者更准确地说，iOS 库对服务器响应的解释对我来说似乎不正确。这是我的代码：

- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
{
    NSURLProtectionSpace *protectionSpace = [challenge protectionSpace];
    NSString *authenticationMethod = [protectionSpace authenticationMethod];

    if ([authenticationMethod isEqualToString:NSURLAuthenticationMethodClientCertificate])
    {
        NSURLCredential* credential = [ self buildCredentialClientCert];

        if ( credential == nil )
        {
            [[challenge sender] cancelAuthenticationChallenge:challenge];
        }
        else
        {
            [[challenge sender] useCredential:credential forAuthenticationChallenge:challenge];
        }
    }
    else if ([authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust])
    {
        .... // do other stuff

问题是，即使我知道服务器支持客户端证书身份验证，当我设置断点时，authenticationMethod 总是设置为NSURLAuthenticationMethodServerTrust。

原始 HTTPS 服务器响应包含以下内容：

错误代码：403 禁止。该页面需要客户端证书作为身份验证过程的一部分。如果您使用智能卡，则需要插入智能卡以选择适当的证书。否则，请联系您的服务器管理员。 (12213)

我的问题是，是什么决定了身份验证挑战是 NSURLAuthenticationMethodServerTrust 还是 NSURLAuthenticationMethodClientCertificate？

Answer 1

由于没有人回答这个问题，我最终确实找到了一个可行的解决方案，就在这里。

服务器信任不是服务器对客户端的挑战，它是客户端验证服务器提供的信任的机会。考虑到这一点，下面的代码不会验证该信任，但可以。

通常你会得到 NSURLAuthenticationMethodServerTrust，然后你会得到 NSURLAuthenticationMethodClientCertificate。这不是非此即彼。这是工作代码。

- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge
{
    NSURLProtectionSpace *protectionSpace = [challenge protectionSpace];
    NSString *authenticationMethod = [protectionSpace authenticationMethod];

    if ([authenticationMethod isEqualToString:NSURLAuthenticationMethodClientCertificate] && self.accountCertKeychainRef != nil)
    {
        SecIdentityRef identity = [KeychainUtilities retrieveIdentityWithPersistentRef:self.accountCertKeychainRef];

        NSURLCredential* credential = [CertificateUtilities getCredentialFromCert:identity];

        if ( credential == nil )
        {
            [[challenge sender] cancelAuthenticationChallenge:challenge];
        }
        else
        {
            [[challenge sender] useCredential:credential forAuthenticationChallenge:challenge];
        }
    }
    else if ([authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust])
    {
        NSURLCredential *credential = [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust];
        [challenge.sender useCredential:credential forAuthenticationChallenge:challenge];
    }
    else if ([authenticationMethod isEqualToString:NSURLAuthenticationMethodNTLM] || [authenticationMethod isEqualToString:NSURLAuthenticationMethodHTTPBasic])
    {
        self.lastProtSpace = [challenge protectionSpace];
        if ([challenge previousFailureCount] > 2)
        {
            [[challenge sender] cancelAuthenticationChallenge:challenge];
        }
        else
        {
            [[challenge sender]  useCredential:[self buildCredential] forAuthenticationChallenge:challenge];
        }

    }
    else
    {
        [[challenge sender] cancelAuthenticationChallenge:challenge];
    }
}

对于以下问题，您可以通过以下方式获取身份：

+ (SecIdentityRef)copyIdentityAndTrustWithCertData:(CFDataRef)inPKCS12Data password:(CFStringRef)keyPassword
{
    SecIdentityRef extractedIdentity = nil;
    OSStatus securityError = errSecSuccess;

    const void *keys[] = {kSecImportExportPassphrase};
    const void *values[] = {keyPassword};
    CFDictionaryRef optionsDictionary = NULL;

    optionsDictionary = CFDictionaryCreate(NULL, keys, values, (keyPassword ? 1 : 0), NULL, NULL);

    CFArrayRef items = NULL;
    securityError = SecPKCS12Import(inPKCS12Data, optionsDictionary, &items);

    if (securityError == errSecSuccess) {
        CFDictionaryRef myIdentityAndTrust = CFArrayGetValueAtIndex(items, 0);

        // get identity from dictionary
        extractedIdentity = (SecIdentityRef)CFDictionaryGetValue(myIdentityAndTrust, kSecImportItemIdentity);
        CFRetain(extractedIdentity);
    }

    if (optionsDictionary) {
        CFRelease(optionsDictionary);
    }

    if (items) {
        CFRelease(items);
    }

    return extractedIdentity;
}

对于那些感兴趣的人，这里是 getCredentialForCert：

+ (NSURLCredential *)getCredentialFromCert:(SecIdentityRef)identity
{
    SecCertificateRef certificateRef = NULL;
    SecIdentityCopyCertificate(identity, &certificateRef);

    NSArray *certificateArray = [[NSArray alloc] initWithObjects:(__bridge_transfer id)(certificateRef), nil];
    NSURLCredentialPersistence persistence = NSURLCredentialPersistenceForSession;

    NSURLCredential *credential = [[NSURLCredential alloc] initWithIdentity:identity
                                                               certificates:certificateArray
                                                                persistence:persistence];

    return credential;
}