隐身图像 [英] steganograpy in image

问题描述

public class Bit
    {

        public static void Replace(ref byte b, int pos, byte value)
        {
            b = (byte) (value == 1 ? b | (1 << pos) : b & ~(1 << pos));
        }

        public static byte Extract(byte b, int pos)
        {
            return (byte) ((b & (1 << pos)) >> pos);
        }

    }

public static void Encode(Stream inStream, byte[] message, Stream outStream)
        {

            int byteRead;
            byte byteWrite;
            int i = 0;
            int j = 0;
            byte bit;

            while((byteRead = inStream.ReadByte()) != -1)
            {

                byteWrite = (byte) byteRead;

                if (i<message.Length)
                {
                    // Extract the bit at the j position
                    bit = Bit.Extract(message[i], j++);

                    // Replace the LSB of byteWrite with "bit"
                    Bit.Replace(ref byteWrite, 0, bit);

                    // Every 8 bits process another byte of "message"
                    if (j==8) {j=0; i++;}
                }

                outStream.WriteByte(byteWrite);
            }

            if (i<message.Length)
                throw new Exception("The cover is too small to contain the message to hide");
        }

此类用于为每个像素隐藏最低有效位中的数据
通过将RGB移位一位.
#如何为每个像素移动四个最低有效位来隐藏数据
#如何通过过滤RGB并使用一种颜色将数据隐藏在蓝色的最低有效位中来隐藏数据

This classes use to hiding data in the Least Significant Bit for each pixel
by shifting one bit from RGB.
# how can hiding data by shifting four Least Significant Bit for each pixel
# how can hiding data by filtering RGB and use one color to hiding data in the Least Significant Bit of blue color

推荐答案

并将其最近上传到Google Code，以防其他人从中受益.它支持将文件编码为每个像素的RGB部分可变数量的位数，加密(包括标题和原始文件名)以及自动调整图像大小，以便图像始终是最佳尺寸.

2Pix主项目页面(包含示例和说明) [使用指针将数据编码为图像的代码(快速). [ ^ ]
代表加密文件的代码(具有合理的可否认性) [

I wrote something to do this a while ago, and recently uploaded it to Google Code in case anyone else could benefit from it. It supports encoding files into a variable number of bits per RGB part of a pixel, encryption (including the header and original file name), and automatic image resizing so that the image is always the best size.

The 2Pix main project page (with examples and descriptions)[^]

Direct links to code:

The code that encodes data into an image using pointers (fast).[^]
The code that represents an encrypted file (with plausible deniability)[^]

报价:

此类用于隐藏数据每个像素的最低有效位
通过从RGB移位一位.

This classes use to hiding data in the Least Significant Bit for each pixel
by shifting one bit from RGB.

实际上，发布的代码替换了原始流的每个字节的每个最低有效位.例如，如果流包含24位图像，则它将替换每个RGB分量的最低有效位.

(1)因此，替换每个RGB组件的一半并不是一个好主意(您可能会注意到该伪像，这没有实现隐藏的目的)

(2)如果您知道图像格式，则可以轻松地有选择地更改RGB分量之一:对于24位图像，每3个读取字节只需要更改其中的一个，直接将其他字节复制到输出流即可.

Actually the code posted replaces each least significant bit of each byte of the original stream. If, for instance, the stream contains a 24 bit image then it replaces the least significant bit of each RGB component.

(1) Hence replacing half of each RGB component doesn''t look a good idea (you''ll probably notice the artifact, failing the very purpose of hiding)

(2) You may easily selectively change one of the RGB component if you know the image format: e.g. for a 24 bit image, every 3 read bytes you just need to change one of them, directly copying the others to the output stream.

我对隐写术一无所知，但是有关它的问题有时会出现.通常，发问者最终会被 Corinna John [

I don''t really know anything about Steganography, but questions about it appear every once and a while. Usually the questioners end up being pointed to articles on Code Project by Corinna John[^]. It might not have exactly the answer you are looking for, but I hope it helps you.

这篇关于隐身图像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！