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Last active July 23, 2024 01:24
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Stronger Encryption and Decryption in Node.js
'use strict';
const crypto = require('crypto');
const ENCRYPTION_KEY = process.env.ENCRYPTION_KEY; // Must be 256 bits (32 characters)
const IV_LENGTH = 16; // For AES, this is always 16
function encrypt(text) {
let iv = crypto.randomBytes(IV_LENGTH);
let cipher = crypto.createCipheriv('aes-256-cbc', Buffer.from(ENCRYPTION_KEY), iv);
let encrypted = cipher.update(text);
encrypted = Buffer.concat([encrypted,]);
return iv.toString('hex') + ':' + encrypted.toString('hex');
function decrypt(text) {
let textParts = text.split(':');
let iv = Buffer.from(textParts.shift(), 'hex');
let encryptedText = Buffer.from(textParts.join(':'), 'hex');
let decipher = crypto.createDecipheriv('aes-256-cbc', Buffer.from(ENCRYPTION_KEY), iv);
let decrypted = decipher.update(encryptedText);
decrypted = Buffer.concat([decrypted,]);
return decrypted.toString();
module.exports = { decrypt, encrypt };
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anarnoli commented May 2, 2022

@neeraj87 your above code really helped me but i am getting an error like this

Error: error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decrypt
at (crypto.js:183:26)
at decryption (/Users/pankajpbaviskar/Desktop/Vishwajeet/Teams/twentyfirstsuperadmin/server/middleware/crypto.js:36:42)

below is my code to decrypt
let textParts = res.locals[0][key].split(':');
let iv = new Buffer.from(textParts[0], 'hex');
let encryptedText = new Buffer.from(textParts[1], 'hex');
let decipher = crypto.createDecipheriv('aes-256-cbc', new Buffer.from(KEY), iv);
let decrypted = decipher.update(encryptedText);
console.log(decrypted, 'first');
decrypted = Buffer.concat([decrypted,'utf8')]);
I think i am getting error for but don't know how to fix it.

Hi great gist! I'm getting two errors -

1st: error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decrypt error if I don't set the decipher to decipher.setAutoPadding(false).

2nd: If I do set it to fix the padding to false .. The decrypted text returned is along the lines of: �ㆠT��2ν��үf$}�b����� y\���Ɇ�2�Rd��_�q �o���֥�"�5T�.... Which of course is false when comparing original text before encryption to decrypted text.

Any ideas?? Why this is decrypting this way?

�ㆠT��2ν��үf$}�b����� y\���Ɇ�2�Rd��_�q �o���֥�"�5T� ��1�J���/���W5���e)�m�V�o�ג!��VVl�E��ϰ/@���ܴ^\��}�Z�Ű2C���v�T �Y��[wx'��6Yw�%���R�^Sǧh+42�Km�#�t����et���C-(� . �B��D�!_���e�0,�-fzO�Z*�ym:h��\d4����b��F�/� �d�����s �%p&l@l�[ǎ���%u��Nڴ�e��u���_�-�_�C�����~��m,���<�(��A�r�6 �a��g@ �,�5Ik��d�������.I�� ������|9 ��N{��B�sW�(�Q���MKAE��_T�H��nR}!�g� �rA�������,J��|�:�c?*�d�b��WJ6��N!S�'��-l

@music2code Any luck on your problem? I am in same situation.

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Thanks @vlucas - If anyone having trouble using code, I did the following.

npm install crypto

Get your 32 character passkey, you can type it yourself or go here and generate it > make sure you change Password length to 32

Copy paste that 32 character string into your .env file

In your .env file, put

ENCRYPTION_KEY = 'paste your 32 character string here'

Now Cut and paste all code from above into a js file eg file.js

In the file you want to use the encrypt and decrypt, use import the code like as follows

const { decrypt, encrypt } = require('./file') // path to your code that was cut and paste

and to use it test it out

let data = encrypt('hello')
console.log(data) // you will see the encrypted string
let dataD = decrypt(data)
console.log(dataD) // you will see the decrypted string 'hello'

Link Updated Password Generator:

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The password generator that you included doesn't load anymore. You can try this one.

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I am unable to run the code.....whenever I am entering the gives me an error...

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Venipa commented Apr 10, 2023

made this package a while ago for server side encrypted payloads to use for backend only:

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nijynot commented Feb 15, 2024

I'm surprised by the glaring mistakes (?) in how the encryption key is actually 16 bytes and IV is 8 bytes?
This is largely because he's reading a string as a buffer, without using the hex argument.


  • Because he's reading the hex strings without the hex argument, it's parsed incorrectly. All hex values are read half their size - so 32 bytes is actually 16 bytes and 16 bytes is 8 bytes. Amending this also fixes the Invalid key length errors that people have in the thread.
// Previously

// Now
Buffer.from(encryptionKey, 'hex')
  • Take note of the line, there's absolutely no reason as why you should need to .slice your string if it's 16 bytes. If you generate a string of 16 bytes, that should fit fully into the createCipheriv function from Node's crypto package.
let iv = Buffer.from(crypto.randomBytes(IV_LENGTH)).toString('hex').slice(0, IV_LENGTH);
  • Added keyGen() function that generates a key for you, so that there's no misunderstanding or ambiguity in how you should generate this key. Saw some people mention other random string generation packages, but there's no reason to have that dependency when you can use crypto's randomBytes directly.
  • Use const for variables instead of let.


There are ways to improve the code futher. If you want to improve this, then you could:

  • Add better error messages for e.g. when cipher formats are incorrect
  • Read and write hex with the prefix 0x for less ambiguity
  • Better TypeScript types for Hex values, etc.

I'll leave that to someone else to figure out although, if someone wants to.

Updated code (2024-02-15)

You should use this instead of OP and OP's TypeScript version posted above.

import crypto from 'crypto';

const ENCRYPTION_KEY: string = process.env.SC_ENCRYPTION_KEY || ''; // Must be 256 bits (32 characters)
const IV_LENGTH: number = 16; // For AES, this is always 16

export function keyGen() {
  return crypto.randomBytes(32).toString('hex');

export function encrypt(plainText: string, keyHex: string = ENCRYPTION_KEY): string {
  const iv = crypto.randomBytes(IV_LENGTH); // Directly use Buffer returned by randomBytes
  const cipher = crypto.createCipheriv('aes-256-cbc', Buffer.from(keyHex, 'hex'), iv);
  const encrypted = Buffer.concat([cipher.update(plainText, 'utf8'),]);

  // Return iv and encrypted data as hex, combined in one line
  return iv.toString('hex') + ':' + encrypted.toString('hex');

export function decrypt(text: string, keyHex: string = ENCRYPTION_KEY): string {
  const [ivHex, encryptedHex] = text.split(':');
  if (!ivHex || !encryptedHex) {
    throw new Error('Invalid or corrupted cipher format');

  const encryptedText = Buffer.from(encryptedHex, 'hex');
  const decipher = crypto.createDecipheriv('aes-256-cbc', Buffer.from(keyHex, 'hex'), Buffer.from(ivHex, 'hex'));
  let decrypted = Buffer.concat([decipher.update(encryptedText),]);

  return decrypted.toString();

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isaackogan commented Feb 19, 2024

Great work @nijynot !

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