Node.js - Set padding in crypto module

Question

I've been looking over the docs for the crypto module in Node, and I'm trying to figure out how to set the padding when doing symmetric encryption. I'm trying to use AES-128-ECB, with PKCS5 padding.

I can't see anywhere that it allows you to specify padding. I would certainly hope this is possible to do using this library. How can I specify padding for symmetric encryption in the crypto module?

Solution

http://nodejs.org/api/crypto.html#crypto_cipher_setautopadding_auto_padding_true

When you disable auto-padding, you can write any padding you wish by simply writing to cipher (which is a stream).

Comments

[ntoskrnl]

Or in other words, if you leave auto-padding enabled, the plaintext will be PKCS#5 padded automatically.

[dsw88]

Ok, that's helpful, thanks! How would I write the correct padding to the string? I'm not super good with cryptography, so writing that correctly is difficult to know how to do.

[Mil0R3]

@ntoskrnl since in iOS the default padding is PKCS#7 and can not be changed, so how to set padding to PKCS#7 in node.js?

[dsw88]

@Veelian Yeah I did, but that was to use PKCS5 padding in Node, which is what I needed. I'm not sure how to set it to PKCS7.

[ntoskrnl]

@dsw88 PKCS#5 padding is the same as PKCS#7 padding.

[dsw88]

Ah I didn't know that, thanks! I'm not super familiar with padding schemes, or other encryption details very much for that matter.

[Aborn Jiang]

for block-size 128-bit, there are no difference between PKCS#5 and PKCS#7.