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A very good W3school tutorial can be found here.

how to aes decrypt in javascript

I’m trying to get the data decoded using Node native methods, I search how to achieve this but it get invalid iv initialization or Unsupported state or unable to authenticate data trying differents iv

  1. aes-128 -> 16 bytes

it results in ->

{ "statusCode": 500,
"message": "Invalid initialization vector" }

let decoded: string = '';
for (let ndx = 0; ndx < hash.length; ndx += 2) {
  let i = parseInt('0x' + hash.substring(ndx, ndx + 2));
  decoded += String.fromCharCode(i);
}

try {
  const password = 'somePassword';
  const key = crypto.scryptSync(password, 'salt', 16);
  const iv = Buffer.alloc(11, password, 'ascii'); // Initialization vector.
  const iv2 = crypto.randomBytes(32)
  const iv3 = iv2.toString('hex').slice(0, 16);
  const iv4 = Buffer.allocUnsafe(32)
  const decipher = crypto.createDecipheriv('aes-128-gcm', key, iv);

  let decrypted = decipher.update(decoded, 'ascii', 'utf8');
  decrypted += decipher.final('utf8');

I’tried many iv but all of them results in ->

Unsupported state or unable to authenticate data

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2

Answers


  1. 0

    AES always has a block size of 128. So if we’re talking about AES-128, -192 or -256 then the number indicates the key size in bits.

    So if you specify aes-128-ccm then the expected key size is 128 / 8 = 16 bytes. Either you’ll have to specify aes-192-ccm or the key size needs to be 16 rather than 24 in your scryptSync function. Which one is correct depends of course on how the encryption is performed.

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  2. 0 
        const crypto = require('crypto');

const encryptedData = '<your_encrypted_data>'; 
const iv = Buffer.from('<your_iv>', 'base64'); 


const password = 'somePassword';
const key = crypto.scryptSync(password, 'salt', 16); // 16 bytes key for AES-128

const decipher = crypto.createDecipheriv('aes-128-cbc', key, iv);

decipher.setEncoding('utf8');

let decrypted = decipher.update(encryptedData, 'base64', 'utf8');
decrypted += decipher.final('utf8');

console.log(decrypted);
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