使用AES加密在Swift中加密/解密UIImage

I am piggybacking off of Encrypt/decrypt for Image on IOS UIImage encryption strategy which uses Obj-c to achieve what I am looking for in Swift. For now, ignore the "save to library" issue there, as I am having issues with decrypting in the app itself.

我正在利用iosuiimage加密策略上的图像加密/解密，该策略使用object -c实现我在Swift中寻找的内容。现在，忽略“保存到库”的问题，因为我在应用程序本身中存在解密问题。

The encryption step seems to work fine, and I do get an encrypted image out to imageView.image, but when I try to decrypt I get another image which appears to be encrypted, never back to the original .png image.

加密步骤似乎工作得很好，我确实得到了一个加密的图像到imageView。图像，但是当我尝试解密时，我得到了另一个图像，它看起来是加密的，永远不会回到原始的。png图像。

Any thoughts as to where I went wrong? AES encryption files here: https://github.com/alexeypro/EncryptDecrypt

你知道我哪里出错了吗?这里是AES加密文件:https://github.com/alexeypro/EncryptDecrypt

Encryption / Decryption:

加密/解密:

func pixelEncryptDecrypt() {

    let image = imageView.image!
    var imageRef = image.CGImage

    let width = CGImageGetWidth(imageRef)
    let height = CGImageGetHeight(imageRef)
    let colorSpace = CGColorSpaceCreateDeviceRGB()
    let bytesPerPixel: UInt = 4
    let bytesPerRow: UInt = bytesPerPixel * width
    let bitsPerComponent: UInt = 8

    let sizeOfRawDataInBytes: Int = Int(height * width * 4)
    var rawData = UnsafeMutablePointer<Void>.alloc(sizeOfRawDataInBytes)

    let context = CGBitmapContextCreate(rawData, width, height, bitsPerComponent, bytesPerRow, colorSpace, CGBitmapInfo(CGImageAlphaInfo.PremultipliedLast.rawValue) | CGBitmapInfo.ByteOrder32Big)
    CGContextDrawImage(context, CGRectMake(0, 0, CGFloat(width), CGFloat(height)), imageRef)

    var data = NSData(bytes: rawData, length: sizeOfRawDataInBytes)
    data = encrypted ? data.AES256DecryptWithKey(key) : data.AES256EncryptWithKey(key)

    rawData = data.mutableCopy().mutableBytes

    let cryptContext = CGBitmapContextCreate(rawData, width, height, bitsPerComponent, bytesPerRow, colorSpace, CGBitmapInfo(CGImageAlphaInfo.PremultipliedLast.rawValue))
    imageRef = CGBitmapContextCreateImage(cryptContext);

    let encryptedImage = UIImage(CGImage: imageRef)

    imageView.image = encryptedImage

    encrypted = !encrypted

}

1 个解决方案

#1

The issue with the above code was that I assumed the alpha channel of the image, which upon further research was a silly mistake. I replaced the assumed alpha channel of CGImageAlphaInfo.PremultipliedLast with a variable let alphaInfo = CGImageGetAlphaInfo(imageRef) and passed that variable to both CGBitmapContextCreate calls.

上面代码的问题是我假设了图像的alpha通道，经过进一步的研究，这是一个愚蠢的错误。我替换了假设的CGImageAlphaInfo的alpha通道。PremultipliedLast和一个变量let alphaInfo = CGImageGetAlphaInfo(imageRef)，并将该变量传递给两个CGBitmapContextCreate调用。

func pixelEncryptDecrypt() {
    let image = imageView.image!
    var imageRef = image.CGImage

    let width = CGImageGetWidth(imageRef)
    let height = CGImageGetHeight(imageRef)
    let colorSpace = CGColorSpaceCreateDeviceRGB()
    let bytesPerPixel: UInt = 4
    let bytesPerRow: UInt = bytesPerPixel * width
    let bitsPerComponent: UInt = 8

    let alphaInfo = CGImageGetAlphaInfo(imageRef) // this is what solved the issue.

    let sizeOfRawDataInBytes: Int = Int(height * width * 4)
    var rawData = UnsafeMutablePointer<Void>.alloc(sizeOfRawDataInBytes)

    var context = CGBitmapContextCreate(rawData, width, height, bitsPerComponent, bytesPerRow, colorSpace, CGBitmapInfo(alphaInfo.rawValue) | CGBitmapInfo.ByteOrder32Big)
    CGContextDrawImage(context, CGRectMake(0, 0, CGFloat(width), CGFloat(height)), imageRef)

    var data = NSData(bytes: rawData, length: sizeOfRawDataInBytes)
    data = encrypted ? data.AES256DecryptWithKey(key) : data.AES256EncryptWithKey(key)

    rawData = data.mutableCopy().mutableBytes

    context = CGBitmapContextCreate(rawData, width, height, bitsPerComponent, bytesPerRow, colorSpace, CGBitmapInfo(alphaInfo.rawValue))
    imageRef = CGBitmapContextCreateImage(context);

    let encryptedImage = UIImage(CGImage: imageRef)

    imageView.image = encryptedImage

    encrypted = !encrypted
}