使用NSValueTransformer的iOS核心数据加密 [英] iOS Core Data encryption using NSValueTransformer
问题描述
我正在尝试使用Core Data和CommonCrypto加密数据.我正在尝试使用NSValueTransformer延迟加密和解密.
I'm experimenting with encrypting data with Core Data and CommonCrypto. I am trying to use a NSValueTransformer to lazily encrypt and decrypt.
但是，当我现在尝试将加密的数据保存到持久性存储协调器时，它会失败.每次我尝试将我的数据保存到数据库时，它都会给我:
However when I'm now trying save the encrypted data to the persistent store coordinator, it fails. Every time im trying to save my data to the database, it gives me:
-[__ NSCFString字节]:无法识别的选择器已发送到实例
-[__NSCFString bytes]: unrecognized selector sent to instance
我确定这是某种数据库和NSManagedObject不匹配，但我无法弄清楚.我觉得这可能很简单，但是找不到解决方案.我的代码:
I'm sure it's some sort of database and NSManagedObject mismatch, but I can't figure it out. I feel it's probably rather simple, but I can't find the solution. My code:
NSValueTransformer
class TryHardEncryption: NSValueTransformer {
override class func transformedValueClass() -> AnyClass {
return NSString.self
}
override class func allowsReverseTransformation() -> Bool {
return true
}
override func reverseTransformedValue(value: AnyObject?) -> AnyObject? {
if let message = value as? NSString {
let keyString = "12345678901234567890123456789012"
let keyData: NSData! = (keyString as NSString).dataUsingEncoding(NSUTF8StringEncoding) as NSData!
let keyBytes = UnsafeMutablePointer<Void>(keyData.bytes)
print("keyLength = \(keyData.length), keyData = \(keyData)")
let data: NSData! = (message as NSString).dataUsingEncoding(NSUTF8StringEncoding) as NSData!
let dataLength = size_t(data.length)
let dataBytes = UnsafeMutablePointer<Void>(data.bytes)
print("dataLength = \(dataLength), data = \(data)")
let cryptData = NSMutableData(length: Int(dataLength) + kCCBlockSizeAES128)
let cryptPointer = UnsafeMutablePointer<Void>(cryptData!.mutableBytes)
let cryptLength = size_t(cryptData!.length)
let keyLength = size_t(kCCKeySizeAES256)
let operation: CCOperation = UInt32(kCCDecrypt)
let algoritm: CCAlgorithm = UInt32(kCCAlgorithmAES128)
let options: CCOptions = UInt32(kCCOptionPKCS7Padding + kCCOptionECBMode)
var numBytesEncrypted :size_t = 0
let cryptStatus = CCCrypt(operation,
algoritm,
options,
keyBytes, keyLength,
nil,
dataBytes, dataLength,
cryptPointer, cryptLength,
&numBytesEncrypted)
if UInt32(cryptStatus) == UInt32(kCCSuccess) {
// let x: UInt = numBytesEncrypted
cryptData!.length = Int(numBytesEncrypted)
print("DecryptcryptLength = \(numBytesEncrypted), Decrypt = \(cryptData)")
// Not all data is a UTF-8 string so Base64 is used
let base64cryptString = cryptData!.base64EncodedStringWithOptions(.Encoding64CharacterLineLength)
print("base64DecryptString = \(base64cryptString)")
print( "utf8 actual string = \(NSString(data: cryptData!, encoding: NSUTF8StringEncoding))");
return base64cryptString
} else {
print("Error: \(cryptStatus)")
}
}
return nil
}
override func transformedValue(value: AnyObject?) -> AnyObject? {
if let message = value as? NSString {
let keyString = "12345678901234567890123456789012"
let keyData: NSData! = (keyString as NSString).dataUsingEncoding(NSUTF8StringEncoding) as NSData!
let keyBytes = UnsafePointer<UInt8>(keyData.bytes)
print("keyLength = \(keyData.length), keyData = \(keyData)")
let data: NSData! = message.dataUsingEncoding(NSUTF8StringEncoding) as NSData!
let dataLength = Int(data.length)
let dataBytes = UnsafePointer<UInt8>(data.bytes)
print("dataLength = \(dataLength), data = \(data)")
let cryptData = NSMutableData(length: Int(dataLength) + kCCBlockSizeAES128)!
let cryptPointer = UnsafeMutablePointer<UInt8>(cryptData.mutableBytes)
let cryptLength = size_t(cryptData.length)
let keyLength = size_t(kCCKeySizeAES256)
let operation: CCOperation = UInt32(kCCEncrypt)
let algoritm: CCAlgorithm = UInt32(kCCAlgorithmAES128)
let options: CCOptions = UInt32(kCCOptionECBMode + kCCOptionPKCS7Padding)
var numBytesEncrypted :size_t = 0
let cryptStatus = CCCrypt(operation,
algoritm,
options,
keyBytes, keyLength,
nil,
dataBytes, dataLength,
cryptPointer, cryptLength,
&numBytesEncrypted)
if UInt32(cryptStatus) == UInt32(kCCSuccess) {
cryptData.length = Int(numBytesEncrypted)
print("cryptLength = \(numBytesEncrypted), cryptData = \(cryptData)")
// Not all data is a UTF-8 string so Base64 is used
let base64cryptString = cryptData.base64EncodedStringWithOptions(.Encoding64CharacterLineLength)
print("base64cryptString = \(base64cryptString)")
return NSString(string: base64cryptString) as NSObject
} else {
print("Error: \(cryptStatus)")
}
}
return nil
}
}
要使NSValueTransformer正常工作，我要做的是:
What I had to do to get the NSValueTransformer to work is:
let transformer: TryHardEncryption = TryHardEncryption()
NSValueTransformer.setValueTransformer(transformer, forName: "TryHardEncryption")
没有上面的代码，从未调用过NSValueTransformer.
Without the above code, the NSValueTransformer was never called.
我已将数据库字段标记为Transformable类型，并将其命名为:TryHardEncryption.你们知道这是怎么回事吗?
I've marked the database field as the Transformable type and named it: TryHardEncryption. Do you guys know what is wrong here?
编辑它涉及的属性是:
@NSManaged var establishmentDescription: String?
当我调试它们时，加密和解密函数都返回一个字符串.
Both the encrypt and decrypt functions return a String when I debug them.
推荐答案
我终于弄明白了...我对非常对象必须是什么类型以及nsvaluetransformer必须返回什么类型感到困惑.我没有在nsvaluetransformer中将值强制转换为正确的类型，因此我在代码中返回nil.但是，它并没有以我很容易弄清楚的方式崩溃.其次，我将实体列改回了NSObject.在transformedValue方法中返回一个NSData对象，在reverseTransformedValue方法中返回一个NSString.实际上，这是我使其工作所需的全部.非常感谢你的帮助.确实是类型错误.
I finally figured it out... I was confused as to what type very object had to be and what my nsvaluetransformer had to return. I wasnt casting the value to the proper type in the nsvaluetransformer and thus I was returning nil in the code. However it wasnt crashing in a way that I would easily figure this out. Secondly I changed the entity column back to an NSObject. Returned an NSData object in the transformedValue method and a NSString in the reverseTransformedValue method. This was actually all i needed to make it work. Thanks a lot for your help. It indeed was a type error.
这篇关于使用NSValueTransformer的iOS核心数据加密的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
