在IOS上加密/解密图像

我们正在使用加密/解密和UIIMAGE。如果我们加密、解密并在不保存到iphone gallery的情况下使用UIIMAge，那么效果很好，但如果我们加密、保存到gallery、将（加密的图像）加载到应用程序中并对其进行解密，效果就不好

我们使用这个函数来加密/解密/保存/加载

//加密

UIImage *image = self.imageView.image;
CGContextRef ctx;
CGImageRef imageRef = [image CGImage];
NSUInteger width = CGImageGetWidth(imageRef);
NSUInteger height = CGImageGetHeight(imageRef);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
unsigned char *rawData = malloc(height * width * 4);
int valor =(height * width * 4);
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * width;
NSUInteger bitsPerComponent = 8;
CGContextRef context = CGBitmapContextCreate(rawData, width, height,
                                             bitsPerComponent, bytesPerRow, colorSpace,
                                             kCGImageAlphaPremultipliedLast |    kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);

CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
CGContextRelease(context);


    NSData *data = [NSData dataWithBytes:(const void *)rawData length:sizeof(unsigned char)*valor];
   NSData *encryptedData  = [data AES256EncryptWithKey:@"\"thisIsASecre"];


rawData = [encryptedData bytes];


NSData *dataData2 = [NSData dataWithBytes:rawData length:sizeof(rawData)];

ctx = CGBitmapContextCreate(rawData,
                            CGImageGetWidth( imageRef ),
                            CGImageGetHeight( imageRef ),
                            8,
                            CGImageGetBytesPerRow( imageRef ),
                            CGImageGetColorSpace( imageRef ),
                            kCGImageAlphaPremultipliedLast );

imageRef = CGBitmapContextCreateImage (ctx);
UIImage *rawImage = [UIImage imageWithCGImage:imageRef];

self.imageView.image = rawImage;

UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);

CGContextRelease(ctx);

//解密

UIImage *image = self.imageView.image;
CGContextRef ctx;
CGImageRef imageRef = [image CGImage];
NSUInteger width = CGImageGetWidth(imageRef);
NSUInteger height = CGImageGetHeight(imageRef);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
unsigned char *rawData = malloc(height * width * 4);
int valor =(height * width * 4);
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * width;
NSUInteger bitsPerComponent = 8;
CGContextRef context = CGBitmapContextCreate(rawData, width, height,
                                             bitsPerComponent, bytesPerRow, colorSpace,
                                             kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);

CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
CGContextRelease(context);


   NSData *data = [NSData dataWithBytes:(const void *)rawData length:sizeof(unsigned char)*valor];
   NSData *encryptedData  = [data AES256DecryptWithKey:@"\"thisIsASecre"];


rawData = [encryptedData bytes];




ctx = CGBitmapContextCreate(rawData,
                            CGImageGetWidth( imageRef ),
                            CGImageGetHeight( imageRef ),
                            8,
                            CGImageGetBytesPerRow( imageRef ),
                            CGImageGetColorSpace( imageRef ),
                            kCGImageAlphaPremultipliedLast );

imageRef = CGBitmapContextCreateImage (ctx);
UIImage *rawImage = [UIImage imageWithCGImage:imageRef];

self.imageView.image = rawImage;
image = rawImage;

    UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);

CGContextRelease(ctx);

//加载图像

UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.delegate = self;
picker.allowsEditing = YES;

picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;


[self presentViewController:picker animated:YES completion:NULL];


- (void)imagePickerController:(UIImagePickerController *)picker   didFinishPickingMediaWithInfo:(NSDictionary *)info {

self.imageView.image = [info objectForKey:@"UIImagePickerControllerOriginalImage"]; 

[picker dismissViewControllerAnimated:YES completion:NULL];


}

//还有我用来加密/解密的密码

- (NSData *)AES256EncryptWithKey:(NSString *)key
{
// 'key' should be 32 bytes for AES256, will be null-padded otherwise
char keyPtr[kCCKeySizeAES256+1]; // room for terminator (unused)
bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)

// fetch key data
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

NSUInteger dataLength = [self length];

//See the doc: For block ciphers, the output size will always be less than or 
//equal to the input size plus the size of one block.
//That's why we need to add the size of one block here
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc(bufferSize);

size_t numBytesEncrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
                                      keyPtr, kCCKeySizeAES256,
                                      NULL /* initialization vector (optional) */,
                                      [self bytes], dataLength, /* input */
                                      buffer, bufferSize, /* output */
                                      &numBytesEncrypted);
if (cryptStatus == kCCSuccess) {
    //the returned NSData takes ownership of the buffer and will free it on deallocation
    return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
}

free(buffer); //free the buffer;
return nil;
}

- (NSData *)AES256DecryptWithKey:(NSString *)key
{
// 'key' should be 32 bytes for AES256, will be null-padded otherwise
char keyPtr[kCCKeySizeAES256+1]; // room for terminator (unused)
bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)

// fetch key data
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

NSUInteger dataLength = [self length];

//See the doc: For block ciphers, the output size will always be less than or 
//equal to the input size plus the size of one block.
//That's why we need to add the size of one block here
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc(bufferSize);

size_t numBytesDecrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
                                      keyPtr, kCCKeySizeAES256,
                                      NULL /* initialization vector (optional) */,
                                      [self bytes], dataLength, /* input */
                                      buffer, bufferSize, /* output */
                                      &numBytesDecrypted);

if (cryptStatus == kCCSuccess) {
    //the returned NSData takes ownership of the buffer and will free it on deallocation
    return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
}

free(buffer); //free the buffer;
return nil;
}

有人知道有什么问题吗

---

谢谢

如果将位图图像保存到照片库中，它将存储为JPG。JPG的有损格式将完全覆盖您的加密过程。尝试将位图图像转换为PNG图像，然后保存：

UIImage* pngImage = [UIImage imageWithData:UIImagePNGRepresentation(rawImage)];
UIImageWriteToSavedPhotosAlbum(pngImage, nil, nil, NULL);

---

@在我看来，rmaddy好像在保存一个有效的图像。他对图像像素进行加密，然后创建一个具有基本随机像素的图像，并将其存储在照片库中。（并不是说他不应该检查错误返回：）存储在照片库中的图像不总是转换为jpg吗？在这种情况下，您将进行有损压缩，并且无法期望您的加密/解密周期继续存在。@rmaddy他没有加密png或jpg。他正在加密像素数据本身。本质上，他只是随机化位图中各个像素的颜色。然后，他将随机像素转换为CGImage和UIImage，因此他得到的是一幅有效的图像（尽管看起来不是特别有用）@David Oops-我完全误解了这幅图像。谢谢。你有没有验证过，你可以在没有照片库的情况下完成加密/解密周期，恢复原始照片吗？您正在将位图图像存储到库中，它可能存储为JPG。你有没有试过在UIImagePNGRE演示文稿中强制循环图像？首先，感谢你花时间@David and rmaddy。我以前（现在）试过这样做，但现在不起作用。以你的例子来说，我可以加密（并像png一样保存），但如果我从库中拍摄加密的照片或UIImage中的图像不起作用。你是否验证过你可以通过加密/解密往返并取回你的原始照片？-首先，我从相机或图库中拍摄照片并加密。我可以在UIImage中看到加密的照片，我保存了它，效果很好。如果你去画廊，我可以看到加密的照片第二，使用加密的图像（来自UIImage without access gallery），我正确解密（我看到图像“orginal”）并像原始图像一样保存到gallery中。但是如果我做了第二步，从图库中拍摄加密照片，那么我就不再工作了。我知道当你保存到图库中时一定有问题，可能是压缩了照片。@cserrao你知道这个问题吗？