On Dec 23, 10:25 am, Jamaal Scarlett <[email protected]>
wrote:
> From looking at the header file for rijndael it looks like the blocksize is
> still 16, maybe I'm missing it but I didn't see a function to set the
> blocksize. I'm going to keep digging and thank you Jeffrey and Mouse for
> your help, I really appreciatie it.
You are going to need to do something like this:
struct Rijndael_Info32 : public FixedBlockSize<32>, public
VariableKeyLength<16, 16, 32, 8>
{
CRYPTOPP_DLL static const char * CRYPTOPP_API
StaticAlgorithmName() {return "Rijndael32";}
}
class CRYPTOPP_DLL Rijndael32 : public Rijndael_Info32, public
BlockCipherDocumentation
{
....
}
I'm having trouble locating test vectors, though. Obviously, you
cannot trust the PHP implementation in this case since you want to
interoperate with it. You need an independent verification.
Jeff
> On Sunday, December 23, 2012 8:22:10 AM UTC-5, Jeffrey Walton wrote:
>
> > On Dec 23, 8:08 am, Mouse <[email protected]> wrote:
> > > Rijndael specification allows 32-byte block size (AES standard doesn't),
> > > don't know about Rijndael Crypto++ implementation (since in general this
> > > block size is supported by the library, see no reason why not).
> > Indeed (I had to go look at their original paper). From cs.ucsb.edu/
> > ~koc/cs178/docs/rijndael.pdf<http://cs.ucsb.edu/~koc/cs178/docs/rijndael.pdf>:
> > "Rijndael is an iterated block cipher
> > with a variable block length and a variable key length. The block
> > length and the key length can be independently specified to 128, 192
> > or 256 bits."
>
> > > ...
> > > To the Original Poster: you can't do what you want with AES, period. If
> > you
> > > can't reconfigure that server to use a standard algorithm - you're stuck
> > > with Rijndael, which is supported by Crypto ++.
> > Jamaal might also be able to provide an appropriate Rijndael_Info
> > (http://www.cryptopp.com/docs/ref/rijndael_8h_source.html). I have
> > never attempted it, and don't know if it works (or would work). Wei
> > would probably be the best person to answer short of an implementation
> > trial.
>
> > Jeff
>
> > > > On Dec 22, 9:02 pm, Jamaal Scarlett <[email protected]>
> > wrote:
> > > > > I wrote a test program and the output for the mcrypt function
> > > > > : mcrypt_module_get_algo_block_size(MCRYPT_RIJNDAEL_256, NULL) is
> > 32.
> > > > The
> > > > > key lengths from all three libraries is 32.
> > > > No. The key length is 32 byte in the case of AES-256. Its 24 bytes
> > > > with AES-192, and 16 bytes with AES-128. The block size is always 16
> > > > bytes. csrc.nist.gov/publications/fips/fips197/fips-197.pdf.
>
> > > > Rijndael may allow for a 32 byte block size. I don't know about
> > > > additional configurations because I don't use it in non-NIST
> > > > configurations.
>
> > > > mcrypt has a unique feedback size, if I recall correctly. It has had
> > > > interop problems since the time I can remember.
> > > >http://www.google.com/#q=cryptopp+mcryptt+feedback+size.
>
> > > > Jeff
> > > > > On Saturday, December 22, 2012 8:47:15 PM UTC-5, Mouse wrote:
>
> > > > > > The simple answer for AES is you can't. AES allows three key
> > lengths
> > > > (128,
> > > > > > 192, 256 bits), but only one block size (128 bits). AES prototype
> > > > Rijndael
> > > > > > allowed three block sizes as well.
>
> > > > > > Perhaps by Rijndael-256 they meant only the key length? In that
> > case I
> > > > > > would check the encryption mode, padding, etc. match what that
> > server
> > > > is
> > > > > > set up with.
> > > > > > --
> > > > > > Regards,
> > > > > > Mouse
> > > > > > On Dec 22, 2012 8:30 PM, "Jamaal Scarlett" <[email protected]
> > > > <javascript:>>
> > > > > > wrote:
>
> > > > > >> I need to use AES, the server I am communicating with is
> > using
> > > > > >> mcrypt with the encryption mode set to RIJNDAEL_256. From what I
> > have
> > > > > >> found online, this is a non-standard algorithm. I have tried
> > both
> > > > crypto++
> > > > > >> and OpenSSL's crypto library and while their encrypted outputs
> > match,
> > > > I
> > > > > >> cannot get either to match the output from mcrypt. I would use
> > > > mcrypt, but
> > > > > >> there is a memory leak in the init function of the version I am
> > > > > >> using(2.5.7) and I am unable to find the lib(libmcrypt.lib) file
> > for
> > > > any
> > > > > >> more recent version of the mcrypt library.
>
> > > > > >> Thanks for the help,
> > > > > >> Jamaal
>
> > > > > >> On Saturday, December 22, 2012 4:05:32 PM UTC-5, Jeffrey Walton
> > wrote:
>
> > > > > >>> On Dec 22, 12:27 pm, Jamaal Scarlett <[email protected]>
>
> > > > > >>> wrote:
> > > > > >>> > Thank you for the reply. Upon further reading, it looks like
> > the
> > > > 256
> > > > > >>> in
> > > > > >>> > mcrypts RIJNDAEL_256 refers to the block cipher size. Does
> > > > cryptopp
> > > > > >>> aes
> > > > > >>> > support a 32-bit block cipher size?
> > > > > >>> No, AES is a 16 byte block size. SHACAL2 has a larger block size
> > if
> > > > > >>> you need it.
>
> > > > > >>> I believe Zooko (correct me here) needed a cipher with a larger
> > block
> > > > > >>> size and used SHACAL2 for Tahoe-LFS (
> >http://en.wikipedia.org/wiki/
> > > > > >>> Tahoe-LAFS <http://en.wikipedia.org/wiki/Tahoe-LAFS>).
>
> > > > > >>> Jeff
>
> > > > > >>> > On Saturday, December 22, 2012 4:11:58 AM UTC-5, Jeffrey
> > Walton
> > > > wrote:
>
> > > > > >>> > > On Dec 22, 2:21 am, Jamaal Scarlett <
> > [email protected]>
> > > > > >>> wrote:
> > > > > >>> > > > Is it possible to change key lengths. On the wiki it
> > states
> > > > that
> > > > > >>> > > 16,24&32 byte keys are supported in aes but I cannot find
> > any
> > > > > >>> documentation
> > > > > >>> > > on changing itbftomvthe default of 16. I am attempting to
> > > > > >>> encrypt/decrypt
> > > > > >>> > > data to communicate with a server using mcrypt rijndael 256,
> > > > > >>> however there
> > > > > >>> > > is a memory leak in the version of mcrypt we are using. Is
> > 256
> > > > bit
> > > > > >>> > > supported?
>
> > > > > >>> > > Yes. All relevant objects take a key and key size. See, for
> > > > example,
> > > > > >>> > >http://www.cryptopp.com/wiki/**CBC_mode<
> > > >http://www.cryptopp.com/wiki/CBC_mode>.
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