什么是图像隐写抵抗各种攻击的最佳实践？

问题描述

我真的很好奇，因为现在每个频道都可以通过某种方式修改或压缩图片，这可能被认为是对隐写术的攻击。

我们可以分离隐写术到两种基本类型，首先对图像的空间域进行操作，然后对某种变换域进行操作。

以下类型的攻击是我感兴趣的，因为它是无处不在在我们周围（如果你想保存图像在Facebook上，或者如果你想创建一个图像的缩略图或如果你要保存在移动平台上的图像等）：

1. 压缩或重新压缩图像 - 主要用于JPEG图像或
   具有alpha预乘法的PNG图像。


2. 调整大小或缩放图片和几何操作 - 我的意思是图片的
   变换，而不是压缩它，例如。旋转
   图片，更改比例等。

我想问：

1. 根据你的人来保护嵌入式
   消息的最佳方式是什么？如果infinte
   嵌入消息后使用隐写
   机制重新压缩图像？


2. 如果存在任何图片，则嵌入邮件的阈值是与
   调整大小有关吗？在我看来，steganography是
   对图像然后压缩或
   旋转调整大小更敏感或者添加一个噪声的图像。什么是
   steganography的最好的方法阻止你调整图像大小？我的意思是有
   总是一个边缘，我们不能不丢失信息，但
   应该有一些阈值。


3. 图像处理的组合通过第一和
   第二点？

我正在阅读有关抗压图像隐写的许多文章，校正码和汉明距离以获得我们能够隐藏而不损失信息（或如何在有损信道中获得信息）的阈值。然后第一步是使用汉明距离冗余地隐藏我们到空间域的消息。使用RGB图像，我们将选择例如一个三元组作为一位载波，并且修改我们的三色的颜色是汉明距离将是在边缘的中心的方式。我们可以这样做作为重复纠错码或任何其他（最好的做法是像在F5中的汉明码）。

这个想法是我们的​​错误 - 在JPEG压缩图像上使用计算的汉明距离来校正代码将确保嵌入信息在JPEG压缩的许多应用之后仍然存在。当然，所有这些都是以牺牲图像容量为代价，而我们通过错误纠正代码使用冗余。

该方法的链接示例如下：

我对数字图像上的水印技术不太了解，但是我们可以找到一个因为水印的目的几乎与隐写术的目的相同。我们正试图在数字图像中保留版权信息，或者我们正试图在上述各种情况下保护我们隐藏的图像信息。

我想讨论和问你关于今天通过隐写术在数字图像中保护信息的机制。

解决方案

1. 您的第一个问题涉及去除图像中的噪声（当然是隐藏的位）的有损方法。您可能必须用冗余分散它。 LSB可能不工作，位的位置必须分布。这意味着，这些位可能必须在位的各个部分重复，这样，即使其他副本已损坏，您也可以恢复消息。您可能想添加一个散列，以确保消息没有损坏（虽然散列本身的概率）。




2. 一个想法可能是使用久经验证的加密方法，如AES或ECC（密钥管理将是另一个主题）。这将使您的数据位噪声像。位置索引也可以通过类似的方式来确定。原则是创建均匀分布，以阻止数据和位的位置的可预测性或习惯相关性。

希望这可以为您的隐写设计考虑提供一些指导。

I'm really curious about that because nowadays every channel could modify or compress images some way which could be considered as a attack on steganography.

We can divide steganography to two basic types, first operates on spatial domain of image and second operates on some kind of transform domain.

The following types of attacks are of my interest because it is everywhere around us (if you want to save image on facebook or if you want to create a thumbnail of image or if you are going to save the image on mobile platform, etc.):

1. Compression or recompression of image - mainly for JPEG images orPNG images with alpha premultiplication.
2. Resizing or scaling images and geometric manipulation - I mean thetransformation of image other than compressing it, e.g. rotation ofimage, changing the scale etc.

I would like to ask:

1. What is the best way according you people to protect embeddedmessage in image from compression like in JPEG? What about "infinte"recompression of image after embedding message with steganographicmechanism? Would it be still the message readable?
2. Where is the threshold for embedded messages in connection with theresizing of images if there is any? In my opinion steganography ismuch more sensitive to resizing of image then compression orrotation or adding a noise to images. What is the best way forsteganography resistant to resizing of image by you? I mean there isalways an edge where we can't go without losing the message butthere should be some threshold.
3. What about the combination of image manipulation through first andsecond point?

I was reading many papers regarding compression resistant image steganography and basically they are always using error-correcting codes and Hamming distance to get the threshold of what we are able to hide without lossing information (or how to get the information in lossy channel). Then the first step is to hide redundantly our message to spatial domain using Hamming distance. With RGB image we are going to choose for example one triple as a one bit carrier and modifies our triple of colours is a way that the Hamming distance would be "in a center" of edges. We could do this as a repetition error-correcting code or any other (best practice is the Hamming codes like in the F5).

The idea behind this is that our error-correcting code with computed Hamming distances on JPEG compressed images would ensure that embedded information would be still there after many applications of JPEG compression. Of course all of this is at the expense of capacity of image while we are using redundancy through error correcting codes.

Example link on that method is here:http://www.cs.unibo.it/babaoglu/courses/security/resources/documents/Steganography.pdf

I don't know much about watermarking techniques on digital image but probably we could find there a guidance on that topic because the aim of watermarking is almost the same as of steganography. We are trying to retain copyright information in digital images or we are trying to protect our hidden message in image in various situations like above.

I would like to discuss and ask you about today mechanisms of protect information in digital images through steganography. We can share our ideas or sample codes to make world better.

解决方案

1. Your 1st question pertains to lossy methods removing the 'noise' (which are of course, the hidden bits) in your image. You may have to scatter it with redundancy. The LSB may not work as well as the position of the bits has to be distributed. Which means, the bits may have to be at various parts of the bits repetitively, so that, you can recover the message even when the other copies are corrupted. You may like to add a hash to ensure that the message is not corrupted (though the probability of the hash itself may). But redundancy and wider distribution may give you a good chance to survive the bits.

2. An idea may be to use proven cryptographic methods like AES or ECC (key management would be another topic). This will make your data bits "noise like". The position indices may also be determined via similar way. The principle is to create uniform distributions to deter predictability or pastern correlation for both data and location of the bits.

I hope this may give some guides to your steganographic design considerations.

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