Question

我想在我的cocoa应用程序中使用AES256加密一些文件。生成的文件应尽可能小。

这是我的代码：

 static func encryptFile(pathToFile:String, destinationPath:String, key:String) -> Bool {

    var error: NSError?
    let fileContents = NSData(contentsOfFile: pathToFile, options: NSDataReadingOptions.DataReadingMappedIfSafe, error: &error)
    if let fileContents = fileContents {
        println("Trying to encrypt file \(pathToFile)")
        let startTime = NSDate().timeIntervalSince1970
        let encryptedContents = FileEncryptor.AES256Encryption(fileContents, key: key)
        println("ENCRYPTION TIME: \(NSDate().timeIntervalSince1970 - startTime)")

        if let encryptedContents = encryptedContents {
            var writeError: NSError?

            if (encryptedContents.writeToFile(pathToFile, options: NSDataWritingOptions.DataWritingAtomic, error: &writeError)) {
                return true
            } else {
                if (writeError != nil) {
                    println("Cannot write to file \(pathToFile). Error: \(writeError)")
                } else {
                    println("Cannot write to file \(pathToFile)")
                }
                return false
            }
        } else {
            return false
        }

    } else {
        println("Unable to read file \(pathToFile). Error: \(error)");
        return false
    }

}


static func AES256Encryption(dataToEncrypt:NSData, key:String) -> NSData? {
        let keyData: NSData! = (key as NSString).dataUsingEncoding(NSUTF8StringEncoding) as NSData!
        let keyBytes         = UnsafeMutablePointer<Void>(keyData.bytes)
        print("keyLength   = \(keyData.length), keyData   = \(keyData)")

        let dataLength    = size_t(dataToEncrypt.length)
        let dataBytes     = UnsafeMutablePointer<Void>(dataToEncrypt.bytes)
        print("dataLength  = \(dataLength)")

        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(kCCEncrypt)
        let algoritm:  CCAlgorithm = UInt32(kCCAlgorithmAES128)
        let options:   CCOptions   = UInt32(kCCOptionPKCS7Padding + kCCModeCBC)

        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("cryptLength = \(numBytesEncrypted)")

            return cryptData

        } else {
            print("Error: \(cryptStatus)")
            return nil
        }
    }

我遇到两件事： 1.加密文件内容看起来像[文件的一小部分]：

a56f 707a 24cb e965 08dd be3d 1a0d 9e7b
b73f c982 2014 fdae fa29 c63d 4588 ee29
7b03 5fb2 96a5 00be 2871 e3e8 af23 4eac

我宁愿拥有它：

ã.FrÚQ÷¬_ÄC¯Q%,™˜$žKÝôÙ„gC€È•GBvn&V9&´fÓ

我无法解密某些文件。他们中的大多数都很好，但有些则没有。我一直在寻找某种模式，我发现的唯一的事情是，在大多数情况下，正确的文件在加密时会更大，然后在解密/原始时就会更大。

这是我用来解密的功能：

static func decryptFile(pathToFile:String, destinationPath:String, key:String) -> Bool {
    var error: NSError?
    let fileContents = NSData(contentsOfFile: pathToFile, options: NSDataReadingOptions.DataReadingMappedIfSafe, error: &error)
    if let fileContents = fileContents {
        println("Trying to decrypt file \(pathToFile)")
        let startTime = NSDate().timeIntervalSince1970
        let decryptedContents = FileEncryptor.AES256Decryption(fileContents, key: key)
        println("DECRYPTION TIME: \(NSDate().timeIntervalSince1970 - startTime)")
        return NSFileManager.defaultManager().createFileAtPath(destinationPath, contents:decryptedContents, attributes:nil)
    } else {
        println("Unable to read file \(pathToFile). Error: \(error)");
        return false
    }

}

static func AES256Decryption(data:NSData, key: String) -> NSData? {
    let keyData: NSData! = (key as NSString).dataUsingEncoding(NSUTF8StringEncoding) as NSData!
    let keyBytes         = UnsafeMutablePointer<Void>(keyData.bytes)
    print("keyLength   = \(keyData.length)")

    let dataLength    = size_t(data.length)
    let dataBytes     = UnsafeMutablePointer<Void>(data.bytes)
    print("dataLength  = \(dataLength), ")

    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 + kCCModeCBC)

    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)

        return cryptData
    } else {
        print("Error: \(cryptStatus)")
        return nil
    }
}

几乎所有代码都是从SO中获取的，除了我遇到的这些问题外，它似乎工作正常。我使用的密码对于所有文件都是相同的。

任何帮助将不胜感激！

修改关于问题2.似乎我使用的代码是为ECB模式准备的，我已经改为CBC。这意味着我必须增加加密数据的大小。进行此更改后，几乎所有文件都能正常工作，除了一个......使用较小的值时工作正常。该死。

使用CommonCrypt CCrypto AES256加密文件 - 无法解密某些文件

0 个答案: