Is AES the same in libraries PyCrypto & Node.JS Crypto

Question

I am beginnging to wonder if the implementation of AES is different across libraries..

Currently i have a plaintext encrypted with PyCrypto.
Im trying to decrypt the ciphertext with Node.js's Crypto Library..

Basically with PyCrypto..
im using AES-128-CBC with a random generated IV. (which decrypts perfectly in PyCrypto)

However..
On Node.js im doing this

var buf = new Buffer(ciphertext)
var decipher = crypto.createDecipher('aes-128-cbc',aeskey)
buf = decipher.update(buf,'binary', 'binary')
buf += decipher.final('binary')

Which spits out a bunch of Garbage.... ( changing 'binary' to hex/utf8 doesnt help)

As i am using CBC (Cipher Block Chaining)...
i am prepending the IV to the beginning of the ciphertext (16 blocks).. In PyCrypto this works perfectly, similarly to the specification of PGP, CFB usage..

Does anyone know for what reason this is not working???

Am i expecting too much of Node.js's standard libraries?

Answer 1

Documentation does not mention this, but aeskey you're passing to crypto.createDecipher is not the key, but a password, handled to OpenSSL's EVP_BytesToKey function.

To pass the actual raw key data one should use (presently undocumented) crypto.createDecipheriv(cipher, key, iv) function. This applies to ECB mode too, even though there's no IV in ECB.

If this fails, I think, the first step in debugging would be to try with AES KATs to see whenever the decryption code is correct.

I've tripped on a similar issue here: https://github.com/joyent/node/issues/1318