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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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