How to calculate the sha1 hash of a blob using node.js crypto

Question

In my node.js app I would like to upload a file and calculate the sha1 .

I tried the following :

export function calculateHash(file, type){
  const reader = new FileReader();
  var hash = crypto.createHash('sha1');
  hash.setEncoding('hex');
  const testfile = reader.readAsDataURL(file);
  hash.write(testfile);
  hash.end();
  var sha1sum = hash.read();
  console.log(sha1sum);
  // fd.on((end) => {
  //   hash.end();
  //   const test = hash.read();
  // });
}

The file is blob from selecting a file with a file upload button on my website.

How can I calculate the sha1 hash?

CryptoJS is mainly a client library and should not be confused with node.js' crypto module. Which one is it for you? — Artjom B.
– Artjom B., Commented Jun 16, 2016 at 20:40
What's the issue with the code you've presented here? Doesn't it already work? — Artjom B.
– Artjom B., Commented Jun 16, 2016 at 20:41

Kirill · Accepted Answer · 2023-08-20 21:45:15Z

5

if you're reading the contents in as a block, you're making this harder than it needs to be. We do this:

const fs = require('fs');
export function calculateHash(file, type){
  const testFile = fs.readFileSync(file);
  var sha1sum = crypto.createHash('sha1').update(testFile).digest("hex");
  console.log(sha1sum);
}

edited Aug 20, 2023 at 21:45

Kirill

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answered Jun 16, 2016 at 5:39

BobDickinson

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2 Comments

user1526912 Over a year ago

The solution generated an error. Cannot read property 'length' of undefined

Kurtis Streutker Over a year ago

Works fine for me once the spelling is fixed for testfile and testFile

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