aes-256-cbc加密和解密

Question

I am encrypting an audio file using crypto npm module in node.js and trying to decrypt it in the android side using the same algorithm and the key.

The encryption code is :

encyption parameters

var crypto = require('crypto'),
    algorithm = 'aes-256-cbc',
    password = 'somepassword';  //encyption parameters

encryption function

function encrypt(buffer) {
    var cipher = crypto.createCipher(algorithm, password);
    var crypted = Buffer.concat([cipher.update(buffer), cipher.final()]);
    return crypted;
}

Now,for Decryption , we need to use some IV( Initialisation Vector ) and as research says not to use same IV for any two files .

So, I just want to know now how customized IV can be set and random or separate IVs can be generated for each file in node.js using crypto or any other module during encryption.

It will be great if someone can help me out in this.

Answer 1

to create the IV, use the following command to get 16 random bytes:

var iv = crypto.randomBytes(16)

then, when creating the cipher, change

var cipher = crypto.createCipher(algorithm, password);

to

var cipher = crypto.createCipheriv(algorithm, password, iv);

The IV will not be attached to the resulting ciphertext, so you will need to send it separately to the android side (it can be sent in plaintext).