iOS:以编程方式在密钥链中预安装SSL证书

Question

我想在用户访问站点之前在密钥链中安装/保存证书。我有一个HTTPS服务器，我的应用程序在用户访问https://mysite之前对他们进行身份验证。

是否可以通过密钥链中的POST请求安装/保存证书，或者是否可以将该证书(文件)复制到资源包中以将其标记为受信任？

Answer 1

一旦您有了der格式的服务器证书，您就可以尝试以下代码：

+ (void) addCertToKeychain:(NSData*)certInDer
{
    OSStatus            err = noErr;
    SecCertificateRef   cert;

    cert = SecCertificateCreateWithData(NULL, (CFDataRef) certInDer);
    assert(cert != NULL);

    CFTypeRef result;

    NSDictionary* dict = [NSDictionary dictionaryWithObjectsAndKeys:
                          (id)kSecClassCertificate, kSecClass,
                          cert, kSecValueRef, 
                          nil];

    err = SecItemAdd((CFDictionaryRef)dict, &result);
    assert(err == noErr || err == errSecDuplicateItem);

    CFRelease(cert);
}

它会将证书添加到您的应用程序的密钥链沙箱中，即没有其他应用程序会信任您的证书。

Answer 2

来自：http://blog.asolutions.com/2011/02/using-tls-with-self-signed-certificates-or-custom-root-certificates-in-ios/

您有两个选项可用:将服务器证书添加到密钥链或手动执行验证。无论采用哪种方法，您都需要在应用程序中包含一个DER编码的X.509公共证书。在下面的示例中，将其命名为“ios-trusted-cert.der”)，并使用它创建一个SecCertificateRef。(如果服务器的证书是根证书颁发机构链的一部分，则应该安装根证书颁发机构，而不是服务器的证书。)

NSBundle *bundle = [NSBundle bundleForClass:[self class]];
NSData *iosTrustedCertDerData =
  [NSData dataWithContentsOfFile:[bundle pathForResource:@"ios-trusted-cert"
                                                    ofType:@"der"]];
SecCertificateRef certificate =
  SecCertificateCreateWithData(NULL,
                               (CFDataRef) iosTrustedCertDerData);

请记住，SecCertificateCreateWithData遵循内存所有权的创建规则，因此当您不再需要它时，必须对其执行CFRelease操作，以避免内存泄漏。

接下来，您可以将证书添加到应用程序的密钥链中。当您希望iOS对您创建的每个新套接字都信任您的证书时，这是合适的。

- (void) useKeychain: (SecCertificateRef) certificate {
  OSStatus err =
    SecItemAdd((CFDictionaryRef) [NSDictionary dictionaryWithObjectsAndKeys:
                                  (id) kSecClassCertificate, kSecClass,
                                  certificate, kSecValueRef,
                                  nil],
               NULL);
  if ((err == noErr) || // success!
    (err == errSecDuplicateItem)) { // the cert was already added.  Success!
    // create your socket normally.
    // This is oversimplified.  Refer to the CFNetwork Guide for more details.
    CFReadStreamRef readStream;
    CFWriteStreamRef writeStream;
    CFStreamCreatePairWithSocketToHost(NULL,
                                       (CFStringRef)@"localhost",
                                       8443,
                                       &readStream,
                                       &writeStream);
    CFReadStreamSetProperty(readStream,
                            kCFStreamPropertySocketSecurityLevel,
                            kCFStreamSocketSecurityLevelTLSv1);
    CFReadStreamOpen(readStream);
    CFWriteStreamOpen(writeStream);
  } else {
    // handle the error.  There is probably something wrong with your cert.
  }
}

如果您只想验证正在创建的套接字的证书，而不想验证应用程序中的其他套接字，则可以手动验证您对证书的信任。首先，创建一个套接字(假设您的服务器正在侦听客户端所在机器上的端口8443 )，并在其ssl设置中禁用其证书链验证：

- (void) verifiesManually: (SecCertificateRef) certificate {
  CFReadStreamRef readStream;
  CFWriteStreamRef writeStream;
  CFStreamCreatePairWithSocketToHost(NULL,
                                     (CFStringRef)@"localhost",
                                     8443,
                                     &readStream,
                                     &writeStream);
  // Set this kCFStreamPropertySocketSecurityLevel before
  // setting kCFStreamPropertySSLSettings.
  // Setting kCFStreamPropertySocketSecurityLevel
  // appears to override previous settings in kCFStreamPropertySSLSettings
  CFReadStreamSetProperty(readStream,
                          kCFStreamPropertySocketSecurityLevel,
                          kCFStreamSocketSecurityLevelTLSv1);
  // this disables certificate chain validation in ssl settings.
  NSDictionary *sslSettings =
    [NSDictionary dictionaryWithObjectsAndKeys:
     (id)kCFBooleanFalse, (id)kCFStreamSSLValidatesCertificateChain,
     nil];
  CFReadStreamSetProperty(readStream,
                          kCFStreamPropertySSLSettings,
                          sslSettings);
  NSInputStream *inputStream = (NSInputStream *)readStream;
  NSOutputStream *outputStream = (NSOutputStream *)writeStream;
  [inputStream setDelegate:self];
  [outputStream setDelegate:self];
  [inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop]
                         forMode:NSDefaultRunLoopMode];
  [outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop]
                          forMode:NSDefaultRunLoopMode];
  CFReadStreamOpen(readStream);
  CFWriteStreamOpen(writeStream);
}

然后，当您收到套接字已准备好写入数据的回调时，在向服务器写入任何数据或从服务器读取任何数据之前，应验证对服务器包含的证书的信任。首先(1)，使用您连接的服务器的主机名创建客户端SSL策略。主机名将包含在服务器的证书中，以验证DNS将您定向到的服务器是您信任的服务器。接下来(2)，从套接字获取实际的服务器证书。如果服务器的证书是证书链的一部分，则可能有多个与服务器相关联的证书。当您拥有实际的服务器证书时，您可以(3)创建一个信任对象。信任对象表示信任评估的本地上下文。它隔离单独的信任评估，而密钥链证书应用于所有受信任的套接字。有了信任对象后，您可以(4)设置锚定证书，这是您信任的证书。最后(5)，您可以评估信任对象并发现服务器是否可信任。

#pragma mark -
#pragma mark NSStreamDelegate
- (void)stream:(NSStream *)aStream
   handleEvent:(NSStreamEvent)eventCode {
  switch (eventCode) {
    case NSStreamEventNone:
    break;
    case NSStreamEventOpenCompleted:
    break;
    case NSStreamEventHasBytesAvailable:
    break;
    case NSStreamEventHasSpaceAvailable:
      // #1
      // NO for client, YES for server.  In this example, we are a client
      // replace "localhost" with the name of the server to which you are connecting
      SecPolicyRef policy = SecPolicyCreateSSL(NO, CFSTR("localhost"));
      SecTrustRef trust = NULL;
      // #2
      CFArrayRef streamCertificates =
        [aStream propertyForKey:(NSString *) kCFStreamPropertySSLPeerCertificates];
      // #3
      SecTrustCreateWithCertificates(streamCertificates,
                                     policy,
                                     &trust);
      // #4
      SecTrustSetAnchorCertificates(trust,
                                    (CFArrayRef) [NSArray arrayWithObject:(id) self.certificate]);
      // #5
      SecTrustResultType trustResultType = kSecTrustResultInvalid;
      OSStatus status = SecTrustEvaluate(trust, &trustResultType);
      if (status == errSecSuccess) {
        // expect trustResultType == kSecTrustResultUnspecified
        // until my cert exists in the keychain see technote for more detail.
        if (trustResultType == kSecTrustResultUnspecified) {
          NSLog(@"We can trust this certificate! TrustResultType: %d", trustResultType);
        } else {
          NSLog(@"Cannot trust certificate. TrustResultType: %d", trustResultType);
        }
      } else {
        NSLog(@"Creating trust failed: %d", status);
        [aStream close];
      }
      if (trust) {
        CFRelease(trust);
      }
      if (policy) {
        CFRelease(policy);
      }
    break;
    case NSStreamEventErrorOccurred:
      NSLog(@"unexpected NSStreamEventErrorOccurred: %@", [aStream streamError]);
    break;
    case NSStreamEventEndEncountered:
    break;
    default:
    break;
  }
}