Decrypt from AES-ECB ciphertext created with php/mcrypt using node.js

Question

I have an encrypted message using MCRYPT_RIJNDAEL_128, ECB mode, and Base64, I've tried decrypting using crypto(https://www.npmjs.com/package/crypto) with the following code:

var text = '';
var decipher = crypto.createDecipheriv("aes-128-ecb","SOMEKEYHEREWITHLENGTH32ooooooooo", '');
text += decipher.update(data, "base64");
text += decipher.final();

The error I've been getting is: Invalid key length 32.

What should the length of key be? When I attempt to use 16 instead the error thrown is: 'TypeError: error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decrypt'

If client requires to use ECB with key of length 32, how can I make this case valid?

Artjom B. · Accepted Answer · 2015-10-02 22:30:41Z

1

AES is a subset of Rijndael with a fixed block size 128 bit whereas Rijndael supports block sizes of 128, 192 and 256 bit. The 128 in MCRYPT_RIJNDAEL_128 means the block size. The 128 in aes-128-ecb on the other hand means the key size. Both AES and Rijndael support key sizes of 128, 192 and 256 bit.

If you have a 32 character key and this key is not hex-encoded to reach those 32 characters then it is possible that you actually want aes-256-ecb.

Keep in mind that the key encoding might be different than the one in PHP so might need to parse the key into a Buffer with a specific encoding.

Also, please don't use ECB mode. It is insecure. You should use at least CBC mode with a random IV. Since the IV does not need to be secret, you can simply send it along with the ciphertext as a prefix for example. You would then need to slice it off before decryption.

answered Oct 2, 2015 at 22:30

Artjom B.

62k26 gold badges137 silver badges236 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Scott Arciszewski Over a year ago

Additionally, unauthenticated encryption is dangerous.

Collectives™ on Stack Overflow

Decrypt from AES-ECB ciphertext created with php/mcrypt using node.js

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related