如果从一台设备备份到iCloud,然后恢复到另一台设备,则存储在钥匙串中的项目不会被恢复。这不是预期的,AFAIA a" ThisDeviceOnly"访问设置没有使用,使用了kSecAttrAccessibleAfterFirstUnlock(与kSecAttrAccessibleAfterFirstUnlockThisDeviceOnly相反),这应该导致项目被恢复到另一台设备上?
class func createKey() -> NSData?
{
let keychainIdentifierData = kKeychainIdentifier.data(using: String.Encoding.utf8, allowLossyConversion: false)!
let keyData = NSMutableData(length: 64)!
let result = SecRandomCopyBytes(kSecRandomDefault, 64, keyData.mutableBytes.bindMemory(to: UInt8.self, capacity: 64))
if (result != 0)
{
return nil
}
// Store the key in the keychain
let query: [NSString: AnyObject] = [
kSecClass: kSecClassKey,
kSecAttrApplicationTag: keychainIdentifierData as AnyObject,
kSecAttrKeySizeInBits: 512 as AnyObject,
kSecValueData: keyData,
kSecAttrAccessible: kSecAttrAccessibleAfterFirstUnlock
]
let status = SecItemAdd(query as CFDictionary, nil)
if (status != errSecSuccess)
{
return nil
}
return keyData
}
class func getKey() -> NSData?
{
let keychainIdentifierData = kKeychainIdentifier.data(using: String.Encoding.utf8, allowLossyConversion: false)!
// First check in the keychain for an existing key
let query: [NSString: AnyObject] = [
kSecClass: kSecClassKey,
kSecAttrApplicationTag: keychainIdentifierData as AnyObject,
kSecAttrKeySizeInBits: 512 as AnyObject,
kSecReturnData: true as AnyObject
]
// To avoid Swift optimization bug, should use withUnsafeMutablePointer() function to retrieve the keychain item
// See also: http://stackoverflow.com/questions/24145838/querying-ios-keychain-using-swift/27721328#27721328
var dataTypeRef: AnyObject?
let status = withUnsafeMutablePointer(to: &dataTypeRef) { SecItemCopyMatching(query as CFDictionary, UnsafeMutablePointer($0)) }
if status == errSecSuccess {
return (dataTypeRef as! NSData)
}
return nil
}