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RE: [iaik-jce] Data encryption questions ?



hi,

How can i set the blocksize of any particular cipher(eg DES, RC2, RC4). Are
these ciphers block sizes fixed ? (like DES operates on a 64 bit data block
size).

Thanks,

Sachin

> -----Original Message-----
> From:	Andreas Sterbenz [SMTP:Andreas.Sterbenz@iaik.tu-graz.ac.at]
> Sent:	Thursday, September 16, 1999 11:57 AM
> To:	Gadre, Sachin; iaik-jce@iaik.tu-graz.ac.at
> Subject:	Re: [iaik-jce] Data encryption questions ?
> 
> 1. ECB and CBC are equally fast (the difference is negligible)
> 
> 2. We develop under Windows NT, some testing has also been done on Linux
> and Solaris. Any platform with a stable Java VM should work equally well.
> 
> 3. We support both RC2 and RC4. I am not sure what you mean by "written
> in the same way," the algorithms are fairly different.
> 
> 4. The "blocksize" the speedtests refer to is the size of the byte[]
> passed to the cipher's update() call. Larger values reduce
> the overhead thereby increase the speed (also subject to influence by the
> CPU cache). That makes it advisable to pass larger amounts of data to the
> cipher per call, if that is reasonably possibly for your application.
> 
> 5. In difference to the other ciphers RC4 is a stream cipher, which means
> there is no need for a CBC mode or for padding, i.e. you should use
> RC4/ECB/NoPadding.
> 
> 6. DES can be made fairly fast using some tricks. RC2 is a 16-bit
> oriented cipher which makes it less efficient on modern 32 bit CPUs and
> also especially in Java.
> 
> Regards,
> 
>  Andreas Sterbenz              mailto:Andreas.Sterbenz@iaik.tu-graz.ac.at
> 
> -----Ursprüngliche Nachricht-----
> Von: Gadre, Sachin <sgadre@kpmg.com>
> An: 'Andreas Sterbenz' <Andreas.Sterbenz@iaik.tu-graz.ac.at>; Gadre,
> Sachin <sgadre@kpmg.com>; <iaik-jce@iaik.tu-graz.ac.at>
> Gesendet: Donnerstag, 16. September 1999 17:42
> Betreff: RE: [iaik-jce] Data encryption questions ?
> 
> 
> 
> Hi,
> 
> Thanks for the answers. I will be using the JCE algorithms for doing
> data encryption over the wire. we need an algorithm which is sort of a
> standard NIST approved
> algorithm but at the same time is the fastest.
> 
> I have some more questions: -
> 
> 1. Is ECB cipher mode faster than CBC ?
> 
> 2. Is the IAIK-JCE implementation tested on platforms like SUN
> solaris, Macintosh (OS 7.5, 8.0), HP-UX (10.x)
> 
> 3. Does IAIK support RC4 ?  Is the code written the same way as
> for RC2 ?
> 
> 4. According to the howfast.htm document the speed varies with
> the blocksize ? So if i have a higher blocksize then my speed increases ?
> Can you change the blocksize ? What are the
> pitfalls/advantages of doing that ?
> 
> 5. To achieve maximum speed for RC4(data encryption between
> applet and Application server, middleware used is CORBA) which block size
> should i use ?
> which cipher mode ?,  what is the padding scheme to be used
> ?
> 
> 6. I was reading the Cryptography FAQ's on
> RSA's  site and they mentioned that RC2 is 2-3 times faster than DES in
> software. But
> according to your speed test DES is faster.
> Do you know why ?
> 
> Thanks,
> 
> Sachin
> 
> 
> 
> 
> 
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