How to get md5 iterated md5 sum of every chunk, using blueimp jquery upload plugin

Question

I need to calculate and send an iterated md5-hash to my upload-api. But I don't know how.

I´m using the tutorial found here:

http://tutorialzine.com/2013/05/mini-ajax-file-upload-form/

Along with the blueimp jquery upload plugin.

For sending only ONE FILE (file size smaller than chunk size), everything is working fine. But if a file is chunked, then I have no idea, how to catch the chunk to get md5 of it.

At the end I have to make the md5 iteratively like described here:

https://code.google.com/p/crypto-js/#Progressive_Hashing

$('#upload').fileupload({      // This element will accept file drag/drop uploading     dropZone: $('#drop'),      type        : GLOBAL_FORM_METHOD,     method      : "post",   // Type of data-send-method     dataType    : "json",   // Type of data to recieve from api-call     maxChunkSize: GLOBAL_CHUNK_SIZE,     multipart   : true,      // This function is called when a file is added to the queue;     // either via the browse button, or via drag/drop:     add: function (e, data)     {         var reader = new FileReader();         var file = data.files[0];         var jqXHR;          var tpl = $('<li class="working"><input type="text" value="0" data-width="48" data-height="48"'+             ' data-fgColor="#0788a5" data-readOnly="1" data-bgColor="#3e4043" /><p></p><div class="msg"></div><span></span></li>');          // Append the file name and file size         tpl.find('p')             .text( file.name )             .append('<i>' + formatFileSize( file.size ) + '</i>');          // Add the HTML to the UL element         data.context = tpl.appendTo(ul);          // Initialize the knob plugin         tpl.find('input').knob();          // Listen for clicks on the cancel icon         tpl.find('span').click(function()         {             if( tpl.hasClass('working') )             {                 jqXHR.abort();             }              tpl.fadeOut( function()             {                 tpl.remove();             });         });          // Prevent XHR from sending data in "multipart/formData"         data.postMessage = data.files[0].type;         data.contentType = data.files[0].type;          var chunksize = GLOBAL_CHUNK_SIZE > file.size ? file.size : GLOBAL_CHUNK_SIZE;          // Describe the FileReader-DataLoad-Event         reader.onload = function( event )          {             var binary = event.target.result;             var md5 = CryptoJS.MD5(binary).toString();              data.url += "&md5sum=" + md5;              // D A T A   S E N D              jqXHR = data.submit();         };          // ADD url to XHR-object         data.url = GLOBAL_FORM_ACTION;         data.url += "?etf_id=" + GLOBAL_FOLDER_ID;         data.url += "&file_title=" + file.name;          // If the file will be send in one piece...         if( GLOBAL_CHUNK_SIZE > file.size )         {             // ADD url-parameter to XHR-object             data.url += "&size_chunk_start=" + 0;             data.url += "&size_chunk_length=" + chunksize;         }         // This part for the chunks must be in "beforeSend"-Callback,         // because, the chunk-related size-data is undefined in this case         // but available there.          // ADD url-parameter to XHR-object         data.url += "&size_final=" + file.size;          // Read md5-sum and send the file / chunk...         // On multipart "file" is a chunk !         reader.readAsBinaryString( file );     },      beforeSend : function(e, data)     {         var file = data.files[0];          this.find(".msg").hide();          // If the file will be send as chunks...         if( GLOBAL_CHUNK_SIZE < file.size )         {             console.log( "Chunk data: ", data.uploadedBytes, data.chunkSize, file.size, data );              // ADD url-parameter to XHR-object             data.url += "&size_chunk_start=" + data.uploadedBytes;             data.url += "&size_chunk_length=" + data.chunkSize;              if( typeof this.attr('session_id') !== "undefined" )                 data.url += "&session_id=" + this.attr( 'session_id' );         }      }); 

I hope you help, so that I can myself solve this.

Answer 1

This answer to a similar question offers a method to accomplish this. There are also libraries that will do this for you, like CryptoJS

the gist is you pad your file with 0 bytes to reach a certain length that is divisible by a chunk length, then you read the data into a buffer chunk by chunk, and has that data. Then you append that hash for each chunk you read.

MD5 Hash a large file incrementally