NodeJS - CRYPTO : How to calculate a hash from file or string

nodeJs.crypto.calculatingHash.js

var crypto = require('crypto')
  , fs = require('fs')

// Algorithm depends on availability of OpenSSL on platform
// Another algorithms: 'sha1', 'md5', 'sha256', 'sha512' ...
var algorithm = 'sha1'
  , shasum = crypto.createHash(algorithm)

// Updating shasum with file content
var filename = __dirname + "/anything.txt"
  , s = fs.ReadStream(filename)
s.on('data', function(data) {
  shasum.update(data)
})

// making digest
s.on('end', function() {
  var hash = shasum.digest('hex')
  console.log(hash + '  ' + filename)
})

// Calculating hash from string
var textToHash = "Hello, I want a hash from it"
  , shasum2 = crypto.createHash(algorithm)
shasum2.update(textToHash)
var hash2 = shasum2.digest('hex')
console.log(hash2 + '  ' + textToHash)

The Node.js documentation has a pretty good example showing how to make a sha256 CLI.

// sha-cli.js
const filename = process.argv[2];
const crypto = require('crypto');
const fs = require('fs');
const hash = crypto.createHash('sha256');
const input = fs.createReadStream(filename);
input.on('readable', () => {
  const data = input.read();
  if (data)
    hash.update(data);
  else {
    console.log(`${hash.digest('hex')} ${filename}`);
  }
});

Example usage if you saved that code in sha-cli.js file would be:

node sha-cli.js example-input-file.zip

I compiled the dope comments into a fork of this gist. Thanks guys!! https://gist.github.com/moeiscool/fa7401e44965243f1dd42cfe5abfe015

Those looking for a more compact function can use the following.

const createHashFromFile = filePath => new Promise(resolve => {
  const hash = crypto.createHash('sha1');
  fs.createReadStream(filePath).on('data', data => hash.update(data)).on('end', () => resolve(hash.digest('hex')));
});

Call it using the following.

(async () => {
  console.log(await createHashFromFile(__filename));
})();

For a synchronous method of this, use readFileSync rather than Readable Streams.

const crypto = require('crypto');
const fs = require('fs');

let file_buffer = fs.readFileSync('path/to/your/file.txt');
let sum = crypto.createHash('sha256');
sum.update(file_buffer);
const hex = sum.digest('hex');

console.log(hex);

Thankyou so much romellem. May God Bless Always

Note

Many thanks.

what are the libraries to install for SHA256 to work?

thanks @romellem

awesome, thank you @romellem !

For a synchronous method of this, use readFileSync rather than Readable Streams.

const crypto = require('crypto');
const fs = require('fs');

let file_buffer = fs.readFileSync('path/to/your/file.txt');
let sum = crypto.createHash('sha256');
sum.update(file_buffer);
const hex = sum.digest('hex');

console.log(hex);

... until the file size exceeds 2GB, then this doesn't work anymore