iphone - 为什么钥匙串(keychain)服务返回错误的钥匙串(keychain)内容？

Question

我一直在尝试在 iPhone 应用程序中使用持久钥匙串(keychain)引用。我发现如果我创建了两个不同的钥匙串(keychain)项目，我每次都会得到不同的持久引用(它们看起来像“genp.......1”，“genp.......2”，...) 。但是，尝试通过持久引用查找项目始终返回第一个项目的内容。为什么会这样呢？我确认我的钥匙串(keychain)保存代码肯定在每种情况下创建新项目(而不是更新现有项目)，并且没有收到任何错误。正如我所说，钥匙串(keychain)服务为每个项目提供不同的持久引用。

我已经设法通过按属性而不是持久引用搜索钥匙串(keychain)项来解决我眼前的问题，但使用持久引用会更容易，因此我很乐意解决这个问题。

这是我的代码:

- (NSString *)keychainItemWithName: (NSString *)name {
    NSString *path = [GLApplicationSupportFolder()
                      stringByAppendingPathComponent: name];
    NSData *persistentRef = [NSData dataWithContentsOfFile: path];
    if (!persistentRef) {
        NSLog(@"no persistent reference for name: %@", name);
        return nil;
    }
    NSArray *refs = [NSArray arrayWithObject: persistentRef];
    //get the data
    CFMutableDictionaryRef params = CFDictionaryCreateMutable(NULL,
                                                              0,
                                                              &kCFTypeDictionaryKeyCallBacks,
                                                              &kCFTypeDictionaryValueCallBacks);
    CFDictionaryAddValue(params, kSecMatchItemList, refs);
    CFDictionaryAddValue(params, kSecClass, kSecClassGenericPassword);
    CFDictionaryAddValue(params, kSecReturnData, kCFBooleanTrue);
    CFDataRef item = NULL;
    OSStatus result = SecItemCopyMatching(params, (CFTypeRef *)&item);
    CFRelease(params);
    if (result != errSecSuccess) {
        NSLog(@"error %d retrieving keychain reference for name: %@", result, name);
        return nil;
    }
    NSString *token = [[NSString alloc] initWithData: (NSData *)item
                                            encoding: NSUTF8StringEncoding];
    CFRelease(item);
    return [token autorelease];
}

- (void)setKeychainItem: (NSString *)newToken forName: (NSString *)name {
    NSData *tokenData = [newToken dataUsingEncoding: NSUTF8StringEncoding];
    //firstly, find out whether the item already exists
    NSDictionary *searchAttributes = [NSDictionary dictionaryWithObjectsAndKeys:
                                      name, kSecAttrAccount,
                                      kCFBooleanTrue, kSecReturnAttributes,
                                      nil];
    NSDictionary *foundAttrs = nil;
    OSStatus searchResult = SecItemCopyMatching((CFDictionaryRef)searchAttributes,
                                                (CFTypeRef *)&foundAttrs);
    if (noErr == searchResult) {
        NSMutableDictionary *toStore = [foundAttrs mutableCopy];
        [toStore setObject: tokenData forKey: (id)kSecValueData];
        OSStatus result = SecItemUpdate((CFDictionaryRef)foundAttrs,
                                        (CFDictionaryRef)toStore);
        if (result != errSecSuccess) {
            NSLog(@"error %d updating keychain", result);
        }
        [toStore release];
        return;
    }
    //need to create the item.
    CFMutableDictionaryRef params = CFDictionaryCreateMutable(NULL,
                                                              0,
                                                              &kCFTypeDictionaryKeyCallBacks,
                                                              &kCFTypeDictionaryValueCallBacks);
    CFDictionaryAddValue(params, kSecClass, kSecClassGenericPassword);
    CFDictionaryAddValue(params, kSecAttrAccount, name);
    CFDictionaryAddValue(params, kSecReturnPersistentRef, kCFBooleanTrue);
    CFDictionaryAddValue(params, kSecValueData, tokenData);
    NSData *persistentRef = nil;
    OSStatus result = SecItemAdd(params, (CFTypeRef *)&persistentRef);
    CFRelease(params);
    if (result != errSecSuccess) {
        NSLog(@"error %d from keychain services", result);
        return;
    }
    NSString *path = [GLApplicationSupportFolder()
                      stringByAppendingPathComponent: name];
    [persistentRef writeToFile: path atomically: NO];
    [persistentRef release];
}

Answer 1

事实证明，使用 kSecMatchItemList 似乎根本不起作用。

我是这样做的:

NSDictionary *query = [NSDictionary dictionaryWithObjectsAndKeys:
                     (id)kSecClassGenericPassword, kSecClass,
                     persistentRef, (id)kSecValuePersistentRef,
                     (id)kCFBooleanTrue, kSecReturnAttributes,
                     (id)kCFBooleanTrue, kSecReturnData,
                     nil];
NSDictionary *result = nil;
OSStatus status = SecItemCopyMatching((CFDictionaryRef)query,
                                    (CFTypeRef*)&result);

它返回持久引用的属性和数据。标题中有关将“持久引用”转换为“标准引用”的文档根本没有意义。希望这会有所帮助。