decipher.update() method in Node.js

decipher.update() is used to update the decryption with the received data according to the given encoding format. It is one of the built-in methods provided by the Decipher class in the crypto module. If the input encoding is specified, the data parameter is a string, otherwise the data parameter is a buffer

Syntax

decipher.update(data, [inputEncoding], [outputEncoding])

Parameters

The above parameters are described as follows-

• data – It requires data as input passed to update the decrypted content.

• inputEncoding - It takes the input encoding as a parameter. Possible input values ​​are hexadecimal, base64, etc.

• outputEncoding – It takes the output encoding as a parameter. The input type of this parameter is string. Possible input values ​​are hexadecimal, base64, etc.

Example

Create a file named decipherUpdate.js and copy the following code snippet. After creating the file, run this code using the following command as shown in the example below -

node decipherUpdate.js

decipherUpdate.js

// Example to demonstrate the use of decipher.final() method

// Importing the crypto module
const crypto = require('crypto');

// Initialising the AES algorithm
const algorithm = 'aes-192-cbc';
// Initialising the password used for generating key
const password = '12345678123456789';

// Retrieving key for the decipher object
const key = crypto.scryptSync(password, 'old data', 24);

// Initializing the static iv
const iv = Buffer.alloc(16, 0);

const decipher = crypto.createDecipheriv(algorithm, key, iv);

// Initializing the decipher object to get decipher
const encrypted = '083bfe1b2f91677e5d00add115be2f1b2e362e190406f5c6b60e86969bf03bff';
// const encrypted2 = '8d11772fce59f08e7558db5bf17b3112';

let decryptedValue = decipher.update(encrypted, 'hex', 'utf8');
// let decryptedValue1 = decipher.update(encrypted1, 'hex', 'utf8');

decryptedValue += decipher.final('utf8');

// Printing the result...
console.log("Decrypted value -- " + decryptedValue);
// console.log("Base64 String:- " + base64Value)

Output

C:\homeode>> node decipherUpdate.js
Decrypted value -- Some new text data

Example

Let’s look at another example.

// Example to demonstrate the use of decipher.final() method

// Importing the crypto module
const crypto = require('crypto');

// Initialising the AES algorithm
const algorithm = 'aes-192-cbc';
// Initialising the password used for generating key
const password = '12345678123456789';

// Retrieving key for the decipher object
crypto.scrypt(password, 'salt', 24,
   { N: 512 }, (err, key) => {
      if (err) throw err;

   // Initializing the static iv
   const iv = Buffer.alloc(16, 0);

   // Initializing the decipher with algo, key and iv
   const decipher = crypto.createDecipheriv(algorithm, key, iv);
   const encrypted = '91d6d37e70fbae537715f0a921d15152194435b96ce3973d92fbbc4a82071074';

   //Getting the decrypted string value
   const decrypted = decipher.update(encrypted, 'hex', 'utf8');

   // Printing the result...
   console.log("Decrypted value:- " + decrypted);
});

Output

C:\homeode>> node decipherUpdate.js
Decrypted value:- Some new text data

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