Block encryption is absolutely secure. This is just an ECB, which is problematic. An implementation can probably be recorded using OFB or CTR mode. However, I never managed to find him. Can bite a bullet and write it ...
UPDATE:
So, I wrote this implementation. For various reasons, I will not publish it here right now (I will try at some point), but here are a few pointers for those who want to do this:
RijndaelManaged CBC. . , ( ) iv - iv - .
, nonce plus iv plus. , nonce iv ( , , , ).
. byte [] GetCurrentCounterBlock (byte [] nonce, byte [] iv, UInt32)
(: "iv" , NIST IV, , IV )
, - , , . TransformBlock . XOR . transform.Reset() , ! CBC . .NET, . , BouncyCastle OFB "", , .
, ( AesCtr256.Process, ) . Stream. , ( , , !).
, , xor /.
: 1.) - . 2.) NIST . , - , , , :).
- , , !