steganography.min.js

/*
 * steganography.js v1.0.3 2017-09-22
 *
 * Copyright (C) 2012 Peter Eigenschink (http://www.peter-eigenschink.at/)
 * Dual-licensed under MIT and Beerware license.
*/
!function(a,b,c){"undefined"!=typeof module&&module.exports?module.exports=c():"function"==typeof define&&define.amd?define(c):b[a]=c()}("steg",this,function(){var a=function(){},b={isPrime:function(a){if(isNaN(a)||!isFinite(a)||a%1||2>a)return!1;if(a%2===0)return 2===a;if(a%3===0)return 3===a;for(var b=Math.sqrt(a),c=5;b>=c;c+=6){if(a%c===0)return!1;if(a%(c+2)===0)return!1}return!0},findNextPrime:function(a){for(var c=a;!0;c+=1)if(b.isPrime(c))return c},sum:function(a,b,c){var d=0;c=c||{};for(var e=c.start||0;b>e;e+=c.inc||1)d+=a(e)||0;return 0===d&&c.defValue?c.defValue:d},product:function(a,b,c){var d=1;c=c||{};for(var e=c.start||0;b>e;e+=c.inc||1)d*=a(e)||1;return 1===d&&c.defValue?c.defValue:d},createArrayFromArgs:function(a,b,c){for(var d=new Array(c-1),e=0;c>e;e+=1)d[e]=a(e>=b?e+1:e);return d},loadImg:function(a){var b=new Image;return b.src=a,b}};return a.prototype.config={t:3,threshold:1,codeUnitSize:16,args:function(a){return a+1},messageDelimiter:function(a,b){for(var c=new Array(3*b),d=0;d<c.length;d+=1)c[d]=255;return c},messageCompleted:function(a,b,c){for(var d=!0,e=0;16>e&&d;e+=1)d=d&&255===a[b+4*e];return d}},a.prototype.getHidingCapacity=function(a,b){b=b||{};var c=this.config,d=b.width||a.width,e=b.height||a.height,f=b.t||c.t,g=b.codeUnitSize||c.codeUnitSize;return f*d*e/g>>0},a.prototype.encode=function(a,c,d){if(c.length)c=b.loadImg(c);else if(c.src)c=b.loadImg(c.src);else if(!(c instanceof HTMLImageElement))throw new Error("IllegalInput: The input image is neither an URL string nor an image.");d=d||{};var e=this.config,f=d.t||e.t,g=d.threshold||e.threshold,h=d.codeUnitSize||e.codeUnitSize,i=b.findNextPrime(Math.pow(2,f)),j=d.args||e.args,k=d.messageDelimiter||e.messageDelimiter;if(!f||1>f||f>7)throw new Error('IllegalOptions: Parameter t = " + t + " is not valid: 0 < t < 8');var l=document.createElement("canvas"),m=l.getContext("2d");l.style.display="none",l.width=d.width||c.width,l.height=d.height||c.height,d.height&&d.width?m.drawImage(c,0,0,d.width,d.height):m.drawImage(c,0,0);var n,o,p,q,r,s,t,u,v,w,x=m.getImageData(0,0,l.width,l.height),y=x.data,z=h/f>>0,A=h%f,B=[];for(v=0;v<=a.length;v+=1){if(s=a.charCodeAt(v)||0,t=A*v%f,t>0&&o){if(u=Math.pow(2,f-t)-1,p=Math.pow(2,h)*(1-Math.pow(2,-t)),q=(s&u)<<t,r=(o&p)>>h-t,B.push(q+r),v<a.length){for(u=Math.pow(2,2*f-t)*(1-Math.pow(2,-f)),w=1;z>w;w+=1)n=s&u,B.push(n>>(w-1)*f+(f-t)),u<<=f;A*(v+1)%f===0?(u=Math.pow(2,h)*(1-Math.pow(2,-f)),n=s&u,B.push(n>>h-f)):f>=A*(v+1)%f+(f-t)&&(n=s&u,B.push(n>>(z-1)*f+(f-t)))}}else if(v<a.length)for(u=Math.pow(2,f)-1,w=0;z>w;w+=1)n=s&u,B.push(n>>w*f),u<<=f;o=s}var C,D,E,F,G,H=k(B,g);for(C=0;4*(C+g)<=y.length&&C+g<=B.length;C+=g){for(G=[],v=0;g>v&&v+C<B.length;v+=1){for(F=0,w=C;g+C>w&&w<B.length;w+=1)F+=B[w]*Math.pow(j(v),w-C);G[v]=255-i+1+F%i}for(v=4*C;v<4*(C+G.length)&&v<y.length;v+=4)y[v+3]=G[v/4%g];E=G.length}for(D=C+E;D-(C+E)<H.length&&4*(C+H.length)<y.length;D+=1)y[4*D+3]=H[D-(C+E)];for(v=4*(D+1)+3;v<y.length;v+=4)y[v]=255;return x.data=y,m.putImageData(x,0,0),l.toDataURL()},a.prototype.decode=function(a,c){if(a.length)a=b.loadImg(a);else if(a.src)a=b.loadImg(a.src);else if(!(a instanceof HTMLImageElement))throw new Error("IllegalInput: The input image is neither an URL string nor an image.");c=c||{};var d=this.config,e=c.t||d.t,f=c.threshold||d.threshold,g=c.codeUnitSize||d.codeUnitSize,h=b.findNextPrime(Math.pow(2,e)),i=(c.args||d.args,c.messageCompleted||d.messageCompleted);if(!e||1>e||e>7)throw new Error('IllegalOptions: Parameter t = " + t + " is not valid: 0 < t < 8');var j=document.createElement("canvas"),k=j.getContext("2d");j.style.display="none",j.width=c.width||a.width,j.height=c.width||a.height,c.height&&c.width?k.drawImage(a,0,0,c.width,c.height):k.drawImage(a,0,0);var l,m,n=k.getImageData(0,0,j.width,j.height),o=n.data,p=[];if(1===f)for(l=3,m=!1;!m&&l<o.length&&!m;l+=4)m=i(o,l,f),m||p.push(o[l]-(255-h+1));var q="",r=0,s=0,t=Math.pow(2,g)-1;for(l=0;l<p.length;l+=1)r+=p[l]<<s,s+=e,s>=g&&(q+=String.fromCharCode(r&t),s%=g,r=p[l]>>e-s);return 0!==r&&(q+=String.fromCharCode(r&t)),q},new a});