在图像中编码隐藏的消息

Question

我想使用 js 在图像中编码隐藏的消息，但不知道这是如何工作的。我一直在寻找一些算法，但没有找到。有人可以解释如何使用js对图像中的消息进行编码吗？

Answer 1

使用此库 https://www.peter-eigenschink.at/projects/steganographyjs/

它将允许您将文本隐藏到图像中

编辑- 从链接添加编码代码

Cover.prototype.encode = function(message, image, options) {
// Handle image url
if(image.length) {
image = util.loadImg(image);
} else if(image.src) {
image = util.loadImg(image.src);
} else if(!(image instanceof HTMLImageElement)) {
throw new Error('IllegalInput: The input image is neither an URL string nor an image.');
}
options = options || {};
var config = this.config;
var t = options.t || config.t,
threshold = options.threshold || config.threshold,
codeUnitSize = options.codeUnitSize || config.codeUnitSize,
prime = util.findNextPrime(Math.pow(2,t)),
args = options.args || config.args,
messageDelimiter = options.messageDelimiter || config.messageDelimiter;
if(!t || t < 1 || t > 7) throw new Error('IllegalOptions: Parameter t = " + t + " is not valid: 0 < t < 8');
var shadowCanvas = document.createElement('canvas'),
shadowCtx = shadowCanvas.getContext('2d');
shadowCanvas.style.display = 'none';
shadowCanvas.width = options.width || image.width;
shadowCanvas.height = options.height || image.height;
if(options.height && options.width) {
shadowCtx.drawImage(image, 0, 0, options.width, options.height );
} else {
shadowCtx.drawImage(image, 0, 0);
}
var imageData = shadowCtx.getImageData(0, 0, shadowCanvas.width, shadowCanvas.height),
data = imageData.data;
// bundlesPerChar ... Count of full t-bit-sized bundles per Character
// overlapping ... Count of bits of the currently handled character which are not handled during each run
// dec ... UTF-16 Unicode of the i-th character of the message
// curOverlapping ... The count of the bits of the previous character not handled in the previous run
// mask ... The raw initial bitmask, will be changed every run and if bits are overlapping
var bundlesPerChar = codeUnitSize/t >> 0,
overlapping = codeUnitSize%t,
modMessage = [],
decM, oldDec, oldMask, left, right,
dec, curOverlapping, mask;
var i, j;
for(i=0; i<=message.length; i+=1) {
dec = message.charCodeAt(i) || 0;
curOverlapping = (overlapping*i)%t;
if(curOverlapping > 0 && oldDec) {
// Mask for the new character, shifted with the count of overlapping bits
mask = Math.pow(2,t-curOverlapping) - 1;
// Mask for the old character, i.e. the t-curOverlapping bits on the right
// of that character
oldMask = Math.pow(2, codeUnitSize) * (1 - Math.pow(2, -curOverlapping));
left = (dec & mask) << curOverlapping;
right = (oldDec & oldMask) >> (codeUnitSize - curOverlapping);
modMessage.push(left+right);
if(i<message.length) {
mask = Math.pow(2,2*t-curOverlapping) * (1 - Math.pow(2, -t));
for(j=1; j<bundlesPerChar; j+=1) {
decM = dec & mask;
modMessage.push(decM >> (((j-1)*t)+(t-curOverlapping)));
mask <<= t;
}
if((overlapping*(i+1))%t === 0) {
mask = Math.pow(2, codeUnitSize) * (1 - Math.pow(2,-t));
decM = dec & mask;
modMessage.push(decM >> (codeUnitSize-t));
}
else if(((((overlapping*(i+1))%t) + (t-curOverlapping)) <= t)) {
decM = dec & mask;
modMessage.push(decM >> (((bundlesPerChar-1)*t)+(t-curOverlapping)));
}
}
}
else if(i<message.length) {
mask = Math.pow(2,t) - 1;
for(j=0; j<bundlesPerChar; j+=1) {
decM = dec & mask;
modMessage.push(decM >> (j*t));
mask <<= t;
}
}
oldDec = dec;
}
// Write Data
var offset, index, subOffset, delimiter = messageDelimiter(modMessage,threshold),
q, qS;
for(offset = 0; (offset+threshold)*4 <= data.length && (offset+threshold) <= modMessage.length; offset += threshold) {
qS=[];
for(i=0; i<threshold && i+offset < modMessage.length; i+=1) {
q = 0;
for(j=offset; j<threshold+offset && j<modMessage.length; j+=1)
q+=modMessage[j]*Math.pow(args(i),j-offset);
qS[i] = (255-prime+1)+(q%prime);
}
for(i=offset*4; i<(offset+qS.length)*4 && i<data.length; i+=4)
data[i+3] = qS[(i/4)%threshold];
subOffset = qS.length;
}
// Write message-delimiter
for(index = (offset+subOffset); index-(offset+subOffset)<delimiter.length && (offset+delimiter.length)*4<data.length; index+=1)
data[(index*4)+3]=delimiter[index-(offset+subOffset)];
// Clear remaining data
for(i=((index+1)*4)+3; i<data.length; i+=4) data[i] = 255;
imageData.data = data;
shadowCtx.putImageData(imageData, 0, 0);
return shadowCanvas.toDataURL();
};