cipher.setAutoPadding(false) causes empty ciphertext to be returned

[adelphes]

• Version: v6.3.0
• Platform: Linux 3.13.0-92-generic Parallel non-io tests #139-Ubuntu SMP x86_64
• Subsystem: crypto

The following code returns an empty string (with no error) as the output from cipher.final('hex'):

const crypto = require('crypto');

// just use a zero buffer for the key and iv...
const key = Buffer.alloc(32);
const iv = Buffer.alloc(16);

const c = crypto.createCipheriv('aes-256-cbc', key, iv);

// disable auto padding because we are encrypting a complete block length
// - this is what appears to mess up cipher.final()
// - commenting this out or setting setAutoPadding(true) works as expected.
c.setAutoPadding(false);

// encrypt the key (with itself!)
c.update(key);

const encdata = c.final('hex');
// for clarity, stringify the result...
console.log('encdata: ' + JSON.stringify(encdata));

// result should be: encdata: "67695e1f7859caf3cd14f3445b9e5f1b"
// result is actually: encdata: ""

Commenting out the setAutoPadding(false) line returns the correct output.

[mscdex]

You're missing the output from .update(). Try this instead:

const encdata = c.update(key, 'buffer', 'hex') + c.final('hex');

[adelphes]

Yeah, sorry - just realised the problem. Will close.