You're right that saying AES is confusing (I asked stopping doing so
on the bug report) but for the wrong reasons ;-)

AES is a subset of Rijndael (fixed block size). FWIW even
RijndaelManaged is a subset of the "real" Rijndael algorithm - but
that's all beside the point.

The real issue is with CFB and the facts that:

* RijndaelManaged CFB is not compatible with AesCryptoServiceProvider
CFB [1] (or with any other CFB implementation in the .NET BCL);

* AesManaged does not support CFB at all [2] (likely not to add
further confusion about it);

So switching to Aes[CryptoServiceProvider|Managed] is not an option
for Drew since he must interoperate with server-side code using the
RijndaelManaged/CFB implementation.

Sebastien

[1] 
http://blogs.msdn.com/b/shawnfa/archive/2006/10/09/the-differences-between-rijndael-and-aes.aspx
[2] 
http://blogs.msdn.com/b/shawnfa/archive/2007/01/17/new-crypto-algorithms-in-orcas.aspx

On Sun, Jan 6, 2013 at 11:27 AM, edward.harvey.mono
<[email protected]> wrote:
>> From: [email protected] [mailto:mono-list-
>> [email protected]] On Behalf Of Drew DeVault
>>
>> The
>> problem comes
>> from using a CryptoStream with a RijndaelManaged cipher.
>
> This might be unrelated, but your subject says AES, and your message body 
> says RijndaelManaged.  AES is based on Rijndael, but AES is not Rijndael.
>
> Most likely you should use AesCryptoServiceProvider or AesManaged instead.  
> The main difference is that AesCryptoServiceProvider takes more time to 
> startup, but it's faster once it's started.  So you use AesManaged for small 
> blocks of data (a few AES blocks worth) and use AesCryptoServiceProvider for 
> everything else.  Also, supposedly AesCryptoServiceProvider isn't necessarily 
> cross-platform compatible, but I have yet to find the platform that doesn't 
> support it.
>
> The Rijndael classes are mostly provided for historic, legacy, and academic 
> purposes nowadays.
>
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