[FIXED] AES Java to Python

Issue

This is an AES encryption code I've gotten from a Java source. This bugs me, as the Cipher itself doesn't use any initial vector in it's initialization - thus I can't seem to to the same thing in Python. Can anyone with a Java background help me understand what this actually does?

byte key[] = {0x13, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00, 0x06, 0x00, 0x00, 0x00, (byte) 0xB4, 0x00, 0x00, 0x00, 0x1B, 0x00, 0x00, 0x00, 0x0F, 0x00, 0x00, 0x00, 0x33, 0x00, 0x00, 0x00, 0x52, 0x00, 0x00, 0x00};
SecretKeySpec skeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
byte[] myIv = {70, 114, 122, 82, 70, 114, 122, 82, 70, 114, 122, 82, 70, 114, 122, 82}
byte[] newIv = cipher.doFinal(myIv);

Solution

The code uses "AES" as algorithm string, which (indeed) resolves to "AES/ECB/PKCS5Padding". It seems you can use AES.MODE_ECB in python using PyCrypto, so it should be no problem replicating that. You may have to implement PKCS#7 padding/unpadding yourself though (or use one of the many examples on the internet). You would not need any IV because ECB doesn't use an IV.

As why a static key is used and why a static IV is being encrypted (with padding) is unknown to me. That can only be clarified by the author of the code. It certainly does not follow best practice.

Answered By - Maarten Bodewes
Answer Checked By - Dawn Plyler (JavaFixing Volunteer)