node.js crypto streams not giving output

Question

I am struggling to understand what I am doing wrong here.

I am trying to write something to encrypt data coming in and out of a TCP socket but I am struggling to get any output from the crypto cipher stream.

Example: (Stripped down to keep it as simple as possible)

crypto = require('crypto');


data.copy(cipherKey,0,5,133); //buffer filled with 128 bytes of data for cipher password.  (source of data stripped out to keep this simple)
//test value (in hex bytes) of cipherKey = abcecfa8c752b72d784db7ddbc30db7da2b22ba7eab9000f2615e26d55a6b27f1ad97239151e1b6398afa055e347571aa018332bef041d032b73e5c23e48407d1e288f8c8edcadd6a70f6f1031cf4778b037b8beaed4863d5ac2e6f4cf454a87ece5051a49d11a2b9a89bf955cbf54a22f05405c43f20f4d4bf26bd2e928189d

var credentials = { algorithm: "aes128", password: cipherKey.toString() };

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

cipher.pipe(process.stdout);

cipher.write("Hello!");

I did manage to get some output (although very little) by repeating the cipher.write("Hello!"); line about 10 times which makes me wonder if you have to input a minimum amount of data before it 'triggers' some output.

If this is the problem then I need to find a way around it since most of the packets that need to go through this will be between 4 and 32 bytes. (although some could be large too, but most not)

Any suggestions?

(I am new to node so I apologise in advance for any stupidity!)

Answer 1

Yes, there is buffering at play here. Just let your crypto stream know there won't be any more data, and it will flush itself.

In your example, just add

cipher.end()