CODEWITHSUNDEEP
javascriptnode.jshashsha1
user1526912
user1526912

Reputation: 17280

How to calculate the checksum of a file in browser and get the same results as from windows command prompt

I am trying to get the checksum/hash from a file upload on my webpage.

I am currently able to upload the file via my browser then calculate the hash using the node.js crypto library. I first convert the blob to a data Url.

export function calculateHash(dataUrl, type){

  const sha1sum = crypto.createHash('sha1').update(dataUrl).digest("hex");
  console.log('Hash sum is ' + sha1sum);

}

Result: 66b8bdd2d1d49f708722c15b26409bc072096697

When i calculate the hash manually from the windows command prompt using the following command..

fciv.exe 1_1.wav -sha1

Result: b06071b13a1b50cd2976ed7bb4180f6963e8db8e

I would like to get the same checksum result from the data url in my browser as doing the manual check from the command prompt.

Is this possible?

Upvotes: 1

Views: 7679

Answers (1)

le_m
le_m

Reputation: 20248

A data url looks like data:image/png;base64,<BASE-64 DATA>. You would need to extract the BASE-64 DATA part, decode base64 and then run your hashing algorithm. Or - if you want to perform the hashing in the browser - use the FileReader API:

function calculateHash(file, callback) {  
  let reader = new FileReader();
  reader.onload = function(event) {
    let file_sha1 = sha1(reader.result);
    callback(file_sha1);
  };
  reader.readAsArrayBuffer(file);
}

let input = document.getElementById("input-file"),
    info = document.getElementById("info");

input.addEventListener("change", function(event) {
  let file = input.files[0];
  
  if (file) {
    calculateHash(file, function(file_sha1) {
      info.textContent = file_sha1;
    });
  }
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/js-sha1/0.6.0/sha1.min.js"></script>

<input id="input-file" type="file">
<div id="info"></div>

Requires js-sha1 (npm install js-sha1).

Credit to: How to checksum the file to be uploaded with javascript?

Upvotes: 4

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