ios - 如何检查 key 是否存储在 Swift 的 KeyChain 中

Question

我试图在 KeyChain 中存储两个私钥和公钥，当我尝试这样做时，我的结果有值(value)返回 0，我假设这意味着它被存储了，但是当我试图返回解密一条消息时，我是将它取回 nil 那么是否有办法检查 key 是否基于存储的 SecItemCopyMatching？但我在创建它们时没有收到任何错误

let tagName = "PrivateKeyTag"
let privkey = "key"
        let privkeyData = Data(privkey!.utf8)
        let privateFilter: [String : Any] = [
            (kSecClass as String)              : kSecClassKey,
            (kSecAttrKeyType as String)        : kSecAttrKeyTypeRSA,
            (kSecAttrApplicationTag as String) : tagName,
            (kSecValueData as String)          : privkeyData,
            (kSecAttrKeyClass as String)       : kSecAttrKeyClassPrivate,
           // kSecAttrKeySizeInBits as String: 2048,
            (kSecReturnPersistentRef as String): true,

            ] as [String : Any]
        let result = SecItemAdd(privateFilter as CFDictionary, nil)
        if ((result != noErr) && (result != errSecDuplicateItem)) {
            NSLog("Cannot add key to keychain, status \(result).")
        }

let getquery: [String: Any] = [kSecClass as String: kSecClassKey,
                                       kSecAttrApplicationTag as String: tag,
                                       kSecAttrKeyType as String: kSecAttrKeyTypeRSA,
                                       ]
        var item: CFTypeRef?
        let status = SecItemCopyMatching(getquery as CFDictionary, &item)
        guard status == errSecSuccess else {
            print("key not found")
            return
        }
        let key = item as! SecKey

Answer 1

当您创建加密 key 时，您可以将参数 kSecAttrIsPermanent 设置为 true，这将自动将 key 存储在默认钥匙串(keychain)中。这将稍微清理您的代码，这样您就不必再处理 S​​ecItemAdd() 和所有错误处理。因此，这是一种更简单的方法来完成您想要做的事情。

创建键和查询键

let tag = "com.example.keys.mykey".data(using: .utf8)!
let attributes: [String: Any] =
    [kSecAttrKeyType as String:            kSecAttrKeyTypeRSA,
     kSecAttrKeySizeInBits as String:      2048,
     kSecPrivateKeyAttrs as String:
        [kSecAttrIsPermanent as String:    true,
         kSecAttrApplicationTag as String: tag]
]

let privateKey = SecKeyCreateRandomKey(attributes as CFDictionary, nil) 
let query: [String: Any] = [kSecClass as String: kSecClassKey,
                            kSecAttrApplicationTag as String: tag,
                            kSecAttrKeyType as String: kSecAttrKeyTypeRSA,
                            kSecReturnRef as String: true]
var item: CFTypeRef?
let status2 = SecItemCopyMatching(query as CFDictionary, &item)
guard status2 == errSecSuccess else { print("error1"); return }
let key = item as! SecKey

我相信运行此代码将完成您在问题中提供的代码中尝试执行的操作。我尝试运行您提供的代码，我使用的 Xcode 和 swift 版本给出了编译器错误。

如果您运行此答案中的代码，您会注意到没有错误打印到控制台，表明已在默认钥匙串(keychain)中成功找到 key 。