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>. > > >> -- > >> You received this message because you are subscribed to the "Crypto++ > >> Users" Google Group. > >> To unsubscribe, send an email to > >> [email protected]<javascript:> > >> . > >> More information about Crypto++ and this group is available at > >>http://www.cryptopp.com. -- You received this message because you are subscribed to the "Crypto++ Users" Google Group. To unsubscribe, send an email to [email protected]. More information about Crypto++ and this group is available at http://www.cryptopp.com.
